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51 INTRODUCTION

The transition-metal mediated reaction for the synthesis of carbon-carbon bonds was

an important discovery for synthetic chemists These metal catalyzed (usually Pd)

reactions are ranked today among the most general transformations in organic

synthesis which have great industrial potential for the synthesis of chemicals

therapeutic drugs and their intermediates The most prevalent method for the synthesis

of carbonyl compounds is palladium catalyzed carbonylation reactions

(Brennfhrer et al 2009) Transition metal-catalyzed carbonylation of aryl halides in

the presence of an appropriate nucleophile represents a valuable tool for the selective

introduction of carboxylic functionality into aromatic molecules Depending on the

nature of the nucleophilic component the products can be aryl esters ketones amides

and aldehydes

Synthesis of aromatic carbonyl compounds such as amides esters ketones

acids have fundamental importance in organic chemistry (Sugihar et al 1994 Brigg

and Sridharan 1993) Phenyl esters are widely used in liquid crystals (Dewar and

Goldberg 1970) photosensitizers (Khoo 1999) and many of them are biologically

active compounds (Neelakantan 1965) Polyesters and polyamides used extensively

in the polymer chemistry (Yoneyama 1989) Aromatic amides are an important

functional group of various natural products and designed pharmaceutical molecules

(Figure 51) Some heterocyclic amides are potential CNS (central nervous system)

active compounds (Hall et al 1995)

Figure 51 Structure of pharmaceutically significant carbonyl compounds

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511 ALKOXYCARBONYLATION REACTIONS

The carbonylation reaction in which aryl halide reacts with carbon monoxide and

alcohol (nucleophile) to give esters as a product is called as alkoxycarbonylation

reaction whereas reaction with phenol gives phenyl ester as a product is called as

phenoxycarbonylation Depending upon the alcoholphenol employed one can get

variety of aliphatic or aromatic esters

In 1996 Nomura and co-workers developed palladium-catalyzed

alkoxycarbonylation of aryl iodides with different alcohols using PdCl2(PPh3)2 as a

catalyst CuI as a co-catalyst and tributylamine as base in DMF as a solvent (Scheme

51) They screened different electron-withdrawing and donating substituents on the

nucleophile In addition carbonylative polyester formation using bis(6-iodophenyl)

ether was also studied

Scheme 51 Palladium-catalyzed alkoxycarbonylation of aryl iodides

Liua et al (2008) demonstrated palladium-catalyzed alkoxycarbonylation of

aryl iodides using a thiourea-oxazoline type ligand under mild reaction conditions

(Scheme 52) Different thiourea type ligands were screened and ligand L1 in the

presence of PdCl2(CH3CN)2 was applied for the alkoxycarbonylation various aryl

iodides and alcohols

Scheme 52 Palladiumthiourea-oxazoline catalyzed alkoxycarbonylation reaction

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Haung and group (2005) has prepared silica-supported sulphur and phosphine

mixed bidentate palladium complex 4-thia-6-chlorohexyltrimethoxysilane was

immobilized on fumed silica followed by reacting with potassium diphenylphosphide

in tetrahydrofuran (THF) and then the reaction with palladium chloride in acetone

The polymeric palladium complex then explored for the carbonylation of aryl halide

with various nucleophiles such as alcohol and amine (Scheme 53) The developed

polymeric palladium complex was recovered and reused without loss of activity

Scheme 53 Si-S P-Pd(II) complex catalyzed carbonylation reactions

Watson et al (2008) reported carbonylation of aryl chlorides at ambient CO

pressure using Pd(dcpp) 2 HBF4 as a efficient catalyst (Scheme 54) The catalyst was

successfully used for aryl and heteroaryl chlorides in combination with variety of

aliphatic and aromatic alcohols The protocol was further employed for the synthesis

of various acid derivatives via carbonylation reactions

Scheme 54 Pd(dcpp) 2HBF4 catalyzed alkoxycarbonylation reaction

Synthesis of tertiary ester by palladium-catalyzed alkoxycarbonylation of aryl

bromides has been reported recently by Xin et al (2012) (Scheme 55) 110-Bis-

(diisopropylphosphino)ferrocene ligand (DiPrPF) applied for the alkoxycarbonylation

of aryl bromides with sodium alkoxide forming tertiary esters Different sodium

alkoxides were screened for the synthesis of verity of tertiary esters

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Scheme 55 Palladium-catalyzed synthesis of tertiary esters

Xia and co-workers (2008) has developed a palladium on charcoal (PdC)

catalyzed protocol for the carbonylation of variety of substrates They demonstrated

phosphine free protocol for the alkoxycarbonylation and phenoxycarbonylation of aryl

iodides using alcohols or phenols as nucleophiles and carbonylative Sonogashira

coupling reaction of aryl iodides with terminal alkynes (Scheme 56) The catalytic

system was applied for the synthesis of variety of esters and alkynyl ketones

Scheme 56 PdC catalyzed carbonylation reactions

Robertson and co-workers (2012) have synthesized polymer-supported tri-

alkyl phosphine ligand this trialkyl phosphine ligands was loaded with palladium and

supported on Merrifield resin This supported complex was then explored for

alkoxycarbonylation reaction and SuzukindashMiyaura coupling reactions (Scheme 57)

Range of carbonyl compounds including aliphaticaromatic esters and substituted

biaryl ketones were synthesized with ease The catalyst was also recycled up to three

consecutive cycles

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Scheme 57 Palladium-catalyzed alkoxycarbonylation of alcoholsphenols

Recently Siva Prasad and Satyanarayana (2013) have prepared PdFe3O4

catalyst and applied for carbonylation of aryl halide with variety of alcohols (Scheme

58) The catalyst was recovered with the simple application of an external magnetic

field due to paramagnetic behaviour of Fe3O4 catalyst was easily separated and was

recycled up to five consecutive cycles

Scheme 58 PdFe3O4 catalyzed alkoxycarbonylation of aryl halides

Palladium-catalyzed carbonylation of phenols (phenoxycarbonylation) has

been developed by Wu et al (2012) (Scheme 59) Activation of the phenols occurs

through in situ generation of aryl nonaflates Both electron-donating and electron-

withdrawing substituents on phenol ring were well tolerated for phenoxycarbonylation

under the developed catalytic system

Scheme 59 [Pd(cinnamyl)Cl2] catalyzed phenoxycarbonylation

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For the first time CO free approach for alkoxycarbonylation of aryl halides

was developed by Yamane and co-workers (2011) (Scheme 510) The molybdenum

carbonyl complexes [Mo(CO)6] act as the catalyst and the source of carbon monoxide

(Scheme 510) The reaction was applied for the multi-acylation of polyols and

synthesis of a variety of carboxylic acid derivatives

Scheme 510 Mo(CO)6-mediated alkoxycarbonylation of aryl halides with alcohols

Another CO free approach using alkyl formates was demonstrated by Beller

and group (2010) (Scheme 511) The reaction was carried out by using palladium(II)

acetaten-butylbis(1-adamantly)phosphine (L1) and DBU as base in NMP as a

solvent The protocol was applied for alkoxycarbonylation of various aryl chlorides

Scheme 511 CO free alkoxycarbonylation of aryl halides using aryl formates

Recently for the first time Zhang et al (2012) reported transition-metal-free

alkoxycarbonylation of aryl halides using Potassium tert-butoxide (KOtBu) and high

pressure of carbon monoxide (Scheme 512) Moreover electron paramagnetic

resonance (EPR) experiments were conducted to study the reaction mechanism which

revealed participation of radicals in the reaction system The major drawback of the

protocol was the use of benzene as a solvent requirement of very high CO pressure

and of longer reaction time

Scheme 512 Transition metal free alkoxycarbonylation of aryl halides

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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511 ALKOXYCARBONYLATION REACTIONS

The carbonylation reaction in which aryl halide reacts with carbon monoxide and

alcohol (nucleophile) to give esters as a product is called as alkoxycarbonylation

reaction whereas reaction with phenol gives phenyl ester as a product is called as

phenoxycarbonylation Depending upon the alcoholphenol employed one can get

variety of aliphatic or aromatic esters

In 1996 Nomura and co-workers developed palladium-catalyzed

alkoxycarbonylation of aryl iodides with different alcohols using PdCl2(PPh3)2 as a

catalyst CuI as a co-catalyst and tributylamine as base in DMF as a solvent (Scheme

51) They screened different electron-withdrawing and donating substituents on the

nucleophile In addition carbonylative polyester formation using bis(6-iodophenyl)

ether was also studied

Scheme 51 Palladium-catalyzed alkoxycarbonylation of aryl iodides

Liua et al (2008) demonstrated palladium-catalyzed alkoxycarbonylation of

aryl iodides using a thiourea-oxazoline type ligand under mild reaction conditions

(Scheme 52) Different thiourea type ligands were screened and ligand L1 in the

presence of PdCl2(CH3CN)2 was applied for the alkoxycarbonylation various aryl

iodides and alcohols

Scheme 52 Palladiumthiourea-oxazoline catalyzed alkoxycarbonylation reaction

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Haung and group (2005) has prepared silica-supported sulphur and phosphine

mixed bidentate palladium complex 4-thia-6-chlorohexyltrimethoxysilane was

immobilized on fumed silica followed by reacting with potassium diphenylphosphide

in tetrahydrofuran (THF) and then the reaction with palladium chloride in acetone

The polymeric palladium complex then explored for the carbonylation of aryl halide

with various nucleophiles such as alcohol and amine (Scheme 53) The developed

polymeric palladium complex was recovered and reused without loss of activity

Scheme 53 Si-S P-Pd(II) complex catalyzed carbonylation reactions

Watson et al (2008) reported carbonylation of aryl chlorides at ambient CO

pressure using Pd(dcpp) 2 HBF4 as a efficient catalyst (Scheme 54) The catalyst was

successfully used for aryl and heteroaryl chlorides in combination with variety of

aliphatic and aromatic alcohols The protocol was further employed for the synthesis

of various acid derivatives via carbonylation reactions

Scheme 54 Pd(dcpp) 2HBF4 catalyzed alkoxycarbonylation reaction

Synthesis of tertiary ester by palladium-catalyzed alkoxycarbonylation of aryl

bromides has been reported recently by Xin et al (2012) (Scheme 55) 110-Bis-

(diisopropylphosphino)ferrocene ligand (DiPrPF) applied for the alkoxycarbonylation

of aryl bromides with sodium alkoxide forming tertiary esters Different sodium

alkoxides were screened for the synthesis of verity of tertiary esters

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Scheme 55 Palladium-catalyzed synthesis of tertiary esters

Xia and co-workers (2008) has developed a palladium on charcoal (PdC)

catalyzed protocol for the carbonylation of variety of substrates They demonstrated

phosphine free protocol for the alkoxycarbonylation and phenoxycarbonylation of aryl

iodides using alcohols or phenols as nucleophiles and carbonylative Sonogashira

coupling reaction of aryl iodides with terminal alkynes (Scheme 56) The catalytic

system was applied for the synthesis of variety of esters and alkynyl ketones

Scheme 56 PdC catalyzed carbonylation reactions

Robertson and co-workers (2012) have synthesized polymer-supported tri-

alkyl phosphine ligand this trialkyl phosphine ligands was loaded with palladium and

supported on Merrifield resin This supported complex was then explored for

alkoxycarbonylation reaction and SuzukindashMiyaura coupling reactions (Scheme 57)

Range of carbonyl compounds including aliphaticaromatic esters and substituted

biaryl ketones were synthesized with ease The catalyst was also recycled up to three

consecutive cycles

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Scheme 57 Palladium-catalyzed alkoxycarbonylation of alcoholsphenols

Recently Siva Prasad and Satyanarayana (2013) have prepared PdFe3O4

catalyst and applied for carbonylation of aryl halide with variety of alcohols (Scheme

58) The catalyst was recovered with the simple application of an external magnetic

field due to paramagnetic behaviour of Fe3O4 catalyst was easily separated and was

recycled up to five consecutive cycles

Scheme 58 PdFe3O4 catalyzed alkoxycarbonylation of aryl halides

Palladium-catalyzed carbonylation of phenols (phenoxycarbonylation) has

been developed by Wu et al (2012) (Scheme 59) Activation of the phenols occurs

through in situ generation of aryl nonaflates Both electron-donating and electron-

withdrawing substituents on phenol ring were well tolerated for phenoxycarbonylation

under the developed catalytic system

Scheme 59 [Pd(cinnamyl)Cl2] catalyzed phenoxycarbonylation

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For the first time CO free approach for alkoxycarbonylation of aryl halides

was developed by Yamane and co-workers (2011) (Scheme 510) The molybdenum

carbonyl complexes [Mo(CO)6] act as the catalyst and the source of carbon monoxide

(Scheme 510) The reaction was applied for the multi-acylation of polyols and

synthesis of a variety of carboxylic acid derivatives

Scheme 510 Mo(CO)6-mediated alkoxycarbonylation of aryl halides with alcohols

Another CO free approach using alkyl formates was demonstrated by Beller

and group (2010) (Scheme 511) The reaction was carried out by using palladium(II)

acetaten-butylbis(1-adamantly)phosphine (L1) and DBU as base in NMP as a

solvent The protocol was applied for alkoxycarbonylation of various aryl chlorides

Scheme 511 CO free alkoxycarbonylation of aryl halides using aryl formates

Recently for the first time Zhang et al (2012) reported transition-metal-free

alkoxycarbonylation of aryl halides using Potassium tert-butoxide (KOtBu) and high

pressure of carbon monoxide (Scheme 512) Moreover electron paramagnetic

resonance (EPR) experiments were conducted to study the reaction mechanism which

revealed participation of radicals in the reaction system The major drawback of the

protocol was the use of benzene as a solvent requirement of very high CO pressure

and of longer reaction time

Scheme 512 Transition metal free alkoxycarbonylation of aryl halides

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Haung and group (2005) has prepared silica-supported sulphur and phosphine

mixed bidentate palladium complex 4-thia-6-chlorohexyltrimethoxysilane was

immobilized on fumed silica followed by reacting with potassium diphenylphosphide

in tetrahydrofuran (THF) and then the reaction with palladium chloride in acetone

The polymeric palladium complex then explored for the carbonylation of aryl halide

with various nucleophiles such as alcohol and amine (Scheme 53) The developed

polymeric palladium complex was recovered and reused without loss of activity

Scheme 53 Si-S P-Pd(II) complex catalyzed carbonylation reactions

Watson et al (2008) reported carbonylation of aryl chlorides at ambient CO

pressure using Pd(dcpp) 2 HBF4 as a efficient catalyst (Scheme 54) The catalyst was

successfully used for aryl and heteroaryl chlorides in combination with variety of

aliphatic and aromatic alcohols The protocol was further employed for the synthesis

of various acid derivatives via carbonylation reactions

Scheme 54 Pd(dcpp) 2HBF4 catalyzed alkoxycarbonylation reaction

Synthesis of tertiary ester by palladium-catalyzed alkoxycarbonylation of aryl

bromides has been reported recently by Xin et al (2012) (Scheme 55) 110-Bis-

(diisopropylphosphino)ferrocene ligand (DiPrPF) applied for the alkoxycarbonylation

of aryl bromides with sodium alkoxide forming tertiary esters Different sodium

alkoxides were screened for the synthesis of verity of tertiary esters

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Scheme 55 Palladium-catalyzed synthesis of tertiary esters

Xia and co-workers (2008) has developed a palladium on charcoal (PdC)

catalyzed protocol for the carbonylation of variety of substrates They demonstrated

phosphine free protocol for the alkoxycarbonylation and phenoxycarbonylation of aryl

iodides using alcohols or phenols as nucleophiles and carbonylative Sonogashira

coupling reaction of aryl iodides with terminal alkynes (Scheme 56) The catalytic

system was applied for the synthesis of variety of esters and alkynyl ketones

Scheme 56 PdC catalyzed carbonylation reactions

Robertson and co-workers (2012) have synthesized polymer-supported tri-

alkyl phosphine ligand this trialkyl phosphine ligands was loaded with palladium and

supported on Merrifield resin This supported complex was then explored for

alkoxycarbonylation reaction and SuzukindashMiyaura coupling reactions (Scheme 57)

Range of carbonyl compounds including aliphaticaromatic esters and substituted

biaryl ketones were synthesized with ease The catalyst was also recycled up to three

consecutive cycles

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Scheme 57 Palladium-catalyzed alkoxycarbonylation of alcoholsphenols

Recently Siva Prasad and Satyanarayana (2013) have prepared PdFe3O4

catalyst and applied for carbonylation of aryl halide with variety of alcohols (Scheme

58) The catalyst was recovered with the simple application of an external magnetic

field due to paramagnetic behaviour of Fe3O4 catalyst was easily separated and was

recycled up to five consecutive cycles

Scheme 58 PdFe3O4 catalyzed alkoxycarbonylation of aryl halides

Palladium-catalyzed carbonylation of phenols (phenoxycarbonylation) has

been developed by Wu et al (2012) (Scheme 59) Activation of the phenols occurs

through in situ generation of aryl nonaflates Both electron-donating and electron-

withdrawing substituents on phenol ring were well tolerated for phenoxycarbonylation

under the developed catalytic system

Scheme 59 [Pd(cinnamyl)Cl2] catalyzed phenoxycarbonylation

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For the first time CO free approach for alkoxycarbonylation of aryl halides

was developed by Yamane and co-workers (2011) (Scheme 510) The molybdenum

carbonyl complexes [Mo(CO)6] act as the catalyst and the source of carbon monoxide

(Scheme 510) The reaction was applied for the multi-acylation of polyols and

synthesis of a variety of carboxylic acid derivatives

Scheme 510 Mo(CO)6-mediated alkoxycarbonylation of aryl halides with alcohols

Another CO free approach using alkyl formates was demonstrated by Beller

and group (2010) (Scheme 511) The reaction was carried out by using palladium(II)

acetaten-butylbis(1-adamantly)phosphine (L1) and DBU as base in NMP as a

solvent The protocol was applied for alkoxycarbonylation of various aryl chlorides

Scheme 511 CO free alkoxycarbonylation of aryl halides using aryl formates

Recently for the first time Zhang et al (2012) reported transition-metal-free

alkoxycarbonylation of aryl halides using Potassium tert-butoxide (KOtBu) and high

pressure of carbon monoxide (Scheme 512) Moreover electron paramagnetic

resonance (EPR) experiments were conducted to study the reaction mechanism which

revealed participation of radicals in the reaction system The major drawback of the

protocol was the use of benzene as a solvent requirement of very high CO pressure

and of longer reaction time

Scheme 512 Transition metal free alkoxycarbonylation of aryl halides

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Scheme 55 Palladium-catalyzed synthesis of tertiary esters

Xia and co-workers (2008) has developed a palladium on charcoal (PdC)

catalyzed protocol for the carbonylation of variety of substrates They demonstrated

phosphine free protocol for the alkoxycarbonylation and phenoxycarbonylation of aryl

iodides using alcohols or phenols as nucleophiles and carbonylative Sonogashira

coupling reaction of aryl iodides with terminal alkynes (Scheme 56) The catalytic

system was applied for the synthesis of variety of esters and alkynyl ketones

Scheme 56 PdC catalyzed carbonylation reactions

Robertson and co-workers (2012) have synthesized polymer-supported tri-

alkyl phosphine ligand this trialkyl phosphine ligands was loaded with palladium and

supported on Merrifield resin This supported complex was then explored for

alkoxycarbonylation reaction and SuzukindashMiyaura coupling reactions (Scheme 57)

Range of carbonyl compounds including aliphaticaromatic esters and substituted

biaryl ketones were synthesized with ease The catalyst was also recycled up to three

consecutive cycles

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Scheme 57 Palladium-catalyzed alkoxycarbonylation of alcoholsphenols

Recently Siva Prasad and Satyanarayana (2013) have prepared PdFe3O4

catalyst and applied for carbonylation of aryl halide with variety of alcohols (Scheme

58) The catalyst was recovered with the simple application of an external magnetic

field due to paramagnetic behaviour of Fe3O4 catalyst was easily separated and was

recycled up to five consecutive cycles

Scheme 58 PdFe3O4 catalyzed alkoxycarbonylation of aryl halides

Palladium-catalyzed carbonylation of phenols (phenoxycarbonylation) has

been developed by Wu et al (2012) (Scheme 59) Activation of the phenols occurs

through in situ generation of aryl nonaflates Both electron-donating and electron-

withdrawing substituents on phenol ring were well tolerated for phenoxycarbonylation

under the developed catalytic system

Scheme 59 [Pd(cinnamyl)Cl2] catalyzed phenoxycarbonylation

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For the first time CO free approach for alkoxycarbonylation of aryl halides

was developed by Yamane and co-workers (2011) (Scheme 510) The molybdenum

carbonyl complexes [Mo(CO)6] act as the catalyst and the source of carbon monoxide

(Scheme 510) The reaction was applied for the multi-acylation of polyols and

synthesis of a variety of carboxylic acid derivatives

Scheme 510 Mo(CO)6-mediated alkoxycarbonylation of aryl halides with alcohols

Another CO free approach using alkyl formates was demonstrated by Beller

and group (2010) (Scheme 511) The reaction was carried out by using palladium(II)

acetaten-butylbis(1-adamantly)phosphine (L1) and DBU as base in NMP as a

solvent The protocol was applied for alkoxycarbonylation of various aryl chlorides

Scheme 511 CO free alkoxycarbonylation of aryl halides using aryl formates

Recently for the first time Zhang et al (2012) reported transition-metal-free

alkoxycarbonylation of aryl halides using Potassium tert-butoxide (KOtBu) and high

pressure of carbon monoxide (Scheme 512) Moreover electron paramagnetic

resonance (EPR) experiments were conducted to study the reaction mechanism which

revealed participation of radicals in the reaction system The major drawback of the

protocol was the use of benzene as a solvent requirement of very high CO pressure

and of longer reaction time

Scheme 512 Transition metal free alkoxycarbonylation of aryl halides

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Scheme 57 Palladium-catalyzed alkoxycarbonylation of alcoholsphenols

Recently Siva Prasad and Satyanarayana (2013) have prepared PdFe3O4

catalyst and applied for carbonylation of aryl halide with variety of alcohols (Scheme

58) The catalyst was recovered with the simple application of an external magnetic

field due to paramagnetic behaviour of Fe3O4 catalyst was easily separated and was

recycled up to five consecutive cycles

Scheme 58 PdFe3O4 catalyzed alkoxycarbonylation of aryl halides

Palladium-catalyzed carbonylation of phenols (phenoxycarbonylation) has

been developed by Wu et al (2012) (Scheme 59) Activation of the phenols occurs

through in situ generation of aryl nonaflates Both electron-donating and electron-

withdrawing substituents on phenol ring were well tolerated for phenoxycarbonylation

under the developed catalytic system

Scheme 59 [Pd(cinnamyl)Cl2] catalyzed phenoxycarbonylation

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For the first time CO free approach for alkoxycarbonylation of aryl halides

was developed by Yamane and co-workers (2011) (Scheme 510) The molybdenum

carbonyl complexes [Mo(CO)6] act as the catalyst and the source of carbon monoxide

(Scheme 510) The reaction was applied for the multi-acylation of polyols and

synthesis of a variety of carboxylic acid derivatives

Scheme 510 Mo(CO)6-mediated alkoxycarbonylation of aryl halides with alcohols

Another CO free approach using alkyl formates was demonstrated by Beller

and group (2010) (Scheme 511) The reaction was carried out by using palladium(II)

acetaten-butylbis(1-adamantly)phosphine (L1) and DBU as base in NMP as a

solvent The protocol was applied for alkoxycarbonylation of various aryl chlorides

Scheme 511 CO free alkoxycarbonylation of aryl halides using aryl formates

Recently for the first time Zhang et al (2012) reported transition-metal-free

alkoxycarbonylation of aryl halides using Potassium tert-butoxide (KOtBu) and high

pressure of carbon monoxide (Scheme 512) Moreover electron paramagnetic

resonance (EPR) experiments were conducted to study the reaction mechanism which

revealed participation of radicals in the reaction system The major drawback of the

protocol was the use of benzene as a solvent requirement of very high CO pressure

and of longer reaction time

Scheme 512 Transition metal free alkoxycarbonylation of aryl halides

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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For the first time CO free approach for alkoxycarbonylation of aryl halides

was developed by Yamane and co-workers (2011) (Scheme 510) The molybdenum

carbonyl complexes [Mo(CO)6] act as the catalyst and the source of carbon monoxide

(Scheme 510) The reaction was applied for the multi-acylation of polyols and

synthesis of a variety of carboxylic acid derivatives

Scheme 510 Mo(CO)6-mediated alkoxycarbonylation of aryl halides with alcohols

Another CO free approach using alkyl formates was demonstrated by Beller

and group (2010) (Scheme 511) The reaction was carried out by using palladium(II)

acetaten-butylbis(1-adamantly)phosphine (L1) and DBU as base in NMP as a

solvent The protocol was applied for alkoxycarbonylation of various aryl chlorides

Scheme 511 CO free alkoxycarbonylation of aryl halides using aryl formates

Recently for the first time Zhang et al (2012) reported transition-metal-free

alkoxycarbonylation of aryl halides using Potassium tert-butoxide (KOtBu) and high

pressure of carbon monoxide (Scheme 512) Moreover electron paramagnetic

resonance (EPR) experiments were conducted to study the reaction mechanism which

revealed participation of radicals in the reaction system The major drawback of the

protocol was the use of benzene as a solvent requirement of very high CO pressure

and of longer reaction time

Scheme 512 Transition metal free alkoxycarbonylation of aryl halides

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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512 AMINOCARBONYLATION REACTION

An aminocarbonylation reaction refers to the carbonylation reaction in which amine

as a nucleophile reacts with aryl halide in the presence of carbon monoxide which

gives amide as a major product Depending upon the amine employed one can get a

variety of aromatic aliphatic and heterocyclic amides

Gee and co-workers (2006) showed the application of microfluidic device for

the rapid synthesis of amides via aminocarbonylation reactions (Scheme 513) They

showed application of microstructure device for first time to perform a gas-liquid

carbonylation reaction The reaction was carriedout on a glass-fabricated Microchip

using Pd(dppp)Cl2 as a catalyst

Scheme 513 Pd phosphine catalyzed aminocarbonylation reaction

Whittall and group (2007) explored Bedford-type palladacycle complex (1) in

combination with Bis(diphenylphosphino)ferrocene ligand (dppf) for the

aminocarbonylation and alkoxycarbonylation reactions (Scheme 514) This palladium

complex acted as highly active catalysts for both the reactions showing compatibility

with a wide variety of substrates

Scheme 514 Palladacycle complex catalyzed carbonylation reactions

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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A method for the aminocarbonylation of aryl bromide using xantphos as a

ligand has been reported recently by Buchwald and group (2008) (Scheme 515) The

method was effective for the direct synthesis of Weinreb amides 1ry

and 2ry

benzamides and methyl esters from the corresponding aryl bromides at atmospheric

pressure of CO The catalytic system was applied for variety of substrates providing

good to excellent yield of desired carbonylated products In addition a putative

catalytic intermediate (Xantphos)Pd(Br)benzoyl was synthesized and an X-ray crystal

structure was also provided This crystal structure revealed that this species possess a

cis-coordinated palladium centre

Scheme 515 Pd(OAc)2 Xantphos catalyzed aminocarbonylation reaction

Kumar et al (2004) demonstrated the aminocarbonylation of unprotected

indoles with different N- and O-nucleophiles using Pddppf as a catalyst (Scheme

516) Various indole carboxylic acid derivatives were accessible in excellent yield

For example aminocarbonylation of 4- 5- 6- or 7-bromoindole with arylethyl

piperazines provided a direct one-step synthesis for CNS active amphetamine

derivatives

Scheme 516 Pd dppf catalyzed aminocarbonylation of bromoindoles

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Pd-catalyzed aminocarbonylation of heteroaryl halides using monodentate

ligand di-tert-butylphosphinoferrocene tetrafluoroborate has been developed by

Senanayake and co-workers (2009) (Scheme 517) The developed protocol was

successfully applied for the preparation of a series of heteroaromatic amide

derivatives in good yields

Scheme 517 Pd P(Fc)(t-Bu)2HBF4 catalyzed aminocarbonylation

Kollar and group reported (2007) Pd(OAc)2PPh3 catalyzed protocol for the

aminocarbonylation of heteroaryl iodides (Scheme 518) Various primary and

secondary amines including amino acid methyl esters were used as nucleophiles in

palladium-catalyzed aminocarbonylation of 2-iodopyridine 3-iodopyridine and

iodopyrazine The reaction works well with variety of nucleophiles having electron-

rich and electron-poor substituents

Scheme 518 Pd(OAc)2PPh3 catalyzed aminocarbonylation of heteroaryl iodides

Well-dispersed palladium(0) nanoparticles stabilized with phosphonium based

ionic liquid were synthesized and explored for the aminocarbonylation reaction of aryl

iodide in ionic liquid media by Zhu et al (2011) (Scheme 519) Different derivatives

of amides were synthesized from corresponding aryl halide and aryl amines

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Scheme 519 Pd(0) nanoparticles catalyzed aminocarbonylation of heteroaryl iodides

An efficient methodology for the synthesis of amides via palladium-catalyzed

aminocarbonylation of aryl iodides was reported by Castill et al (2012) using the

bulky cis-12-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under

atmospheric pressure of carbon monoxide (Scheme 520) A broad range of iodoaryl

derivatives with different amine were screened

Scheme 520 PdP(Fc)(t-Bu)2 catalyzed aminocarbonylation

Recently Dang et al (2012) reported an aminocarbonylation of aryl iodides

using palladium nanoparticles supported on MOF-5 (metal-organic frameworks)

(Scheme 521) Various palladium supported catalysts using different solid supports

like Silica Al2O3 and MOF has been synthesized but palladium catalyst supported on

MOF-5 provided better results The developed catalytic system worked under

atmospheric pressure of carbon monoxide and was applied for the synthesis of various

substituted amides furthermore the catalyst was also recycled

Scheme 521 Pd nanoparticles supported on MOF-5 catalyzed aminocarbonylation

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Begouin et al (2009) have demonstrated that [Mo(CO)6] can be successfully

used as a CO source in aminocarbonylation reactions (Scheme 522) Range of aryl

and heteroaryl substrates either halides or amines were tested for the

aminocarbonylation reactions

Scheme 522 CO free aminocarbonylation using Mo(CO)6

Literature reports reveals that alkoxyphenoxycarbonylation and

aminocarbonylation were well explored by using a variety of homogeneous Pd

complexes with different air and moisture sensitive NP containing ligands which had

problems in the recovery and recycling of the expensive palladium catalyst Also there

is no general protocol developed which could efficiently catalyze the carbonylation of

aryl iodide with different nucleophiles such as phenols alcohols and amines Thus

there is a need to develop a chemically well defined air stable single-component Pd-

complex which can efficiently catalyze different carbonylation reactions including

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

Considering this immobilization strategies for metal complex wherein the

metal is coordinated to a ligand grafted on to an inorganic or organic support has been

developed (Lu and Toy 2009 Byun and Lee 2004) Ionic liquids containing metal

ions are considered as catalytic precursors and they can be immobilized on solid

support thus facilitates the reuse of catalyst finding a promising use in organic

transformations (Doorslaer et al 2010 Sasaki et al 2005 Sasaki et al 2008 Zhong

et al 2006) In this regards immobilized palladium metal ion containing ionic liquid

[ImmPd-IL] is explored for alkoxycarbonylation phenoxycarbonylation and

aminocarbonylation reactions

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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52 RESULTS AND DISCUSSION

Considering the objective of the development of efficient phosphine free

heterogeneous and recyclable protocol immobilized palladium metal ion containing

ionic liquid (ImmPd-IL) was used as a common catalyst for alkoxycarbonylation

phenoxycarbonylation and aminocarbonylation reactions (Scheme 523) The

methodology offers synthesis of various carbonyl compounds including aliphatic

esters aromatic esters and amides from corresponding alcohol phenol and amines

The protocol is advantageous due to the ease in handling of the catalyst and simple

workup procedure and effective catalyst recyclability

Scheme 523 ImmPd-IL catalyzed different carbonylation reactions

521 Preparation of immobilized palladium metal ion containing ionic liquid

(ImmPd-IL) catalyst

Preparation of immobilized palladium metal ion-containing ionic liquid catalyst

(ImmPd-IL) is a two step process (Scheme 524) The first step involves the anchoring

of ionic liquid on to a silica support which gives immobilized ionic liquid (Imm-IL)

In a second step the synthesized Imm-IL is loaded with palladium metal ion (PdCl2)

which results immobilized palladium ion-containing ionic liquid (ImmPd-IL)

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Scheme 524 Preparation of immobilized ImmPd-IL

522 ALKOXYCARBONYLATION REACTIONS

Initially alkoxycarbonylation reaction of aryl iodide with aliphatic alcohols was

studied (Scheme 525)

Scheme 525 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with alcohols

The effect of various reaction parameters like base temperature time and CO

pressure using ImmPd-IL as a catalyst was studied (Table 51) The reaction of

iodobenzene with methyl alcohol in presence of CO was chosen as model reaction for

the optimization To study the role of base the reaction was carried out using various

inorganic bases like K2CO3 (80) Cs2CO3 (79) and organic bases like DBU (85)

Et3N (96) (Table 51 entries 1-4) As Et3N provided maximum yield of the methyl

benzoate it was used for further study No profound increase in the yield of methyl

benzoate was observed when the reaction temperature was increased from 80 to 100

degC therefore 80 degC was considered as an optimum reaction temperature for further

studies (Table 51 entries 4-5) When CO pressure was increased from 73 psi to 145

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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psi equivalent yield of the desired product was observed (Table 51 entry 6) Hence

the finalized reaction conditions were base Et3N temperature 80 degC solvent

alcohol (also as a nucleophile) time 3 h and 73 psi of CO pressure

Table 51 Effect of bases temperature and time on ImmPd-IL catalyzed

alkoxycarbonylation reactiona

Entry Base Temp

(degC)

CO Press

(psi)

Yield

()b

1 K2CO3 80 73 80

2 Cs2CO3 80 73 79

3 DBU 80 73 85

4 Et3N 80 73 96

5 Et3N 100 73 97

6 Et3N 100 145 98

a Reaction conditions

Iodobenzene (2 mmol) methyl alcohol (5 mL) ImmPd-IL (2

mol ) Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Yield based on GC analysis

These optimized reaction parameters were then successfully applied to variety

of aryl iodides with different alcohols (Table 52) Model reaction of iodobenzene

with methyl alcohol provided 94 isolated yield of methyl benzoate (Table 52 entry

1) Ethyl alcohol and benzyl alcohol also reacts efficiently with iodobenzene

providing 95 and 89 yield of ethyl benzoate and benzyl benzoate respectively

(Table 52 entries 1-3) The substituted iodobenzene derivatives 4-iodoaniline and 4-

iodophenol furnished 80 and 75 yield of the methyl 4-aminobenzoate and methyl

4-hydroxybenzoate respectively (Table 52 entries 4-5) 4-Acetyliodobenzene reacts

with ethanol and provided 81 yield of ethyl-4-acetylbenzoate (Table 52 entry 6)

Iodonaphthalene furnished 79 yield of methyl 2-naphthoate (Table 52 entry 7)

whereas 1-iodo-4-nitrobenzene efficiently reacts with methyl alcohol furnishing a

moderate yield (70) of methyl 4-nitrobenzoate (Table 52 entry 8)

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Table 52 ImmPd-IL catalyzed alkoxycarbonylation of aryl iodides with various

alcoholsa

Entry Aryl iodide Alcohol Product Yield

()b

1

MeOH

94

2

EtOH

95

3

89

4

MeOH

80

5

MeOH

75

6

EtOH

81

7

MeOH

79

8

MeOH

70

a Reaction conditions aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

Et3N (3 mmol) 73 psi CO press Temp (80 degC) Time (3 h) b Isolated yield

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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It is believed that the supported palladium metal leaches out from the solid

support and goes into the solution at higher temperature and the reaction was

catalyzed mainly by dissolved palladium species (Tambade et al 2008) Hence to

determine whether the reaction was catalyzed due to the ImmPd-IL complex or a

leached palladium metal that comes off the support at higher temperature during the

reaction a hot filtration test was performed (Lempers 1998 Zhao 2009)

Hot filtration experiment was performed for the alkoxycarbonylation of

iodobenzene with benzyl alcohol using ImmPd-IL catalyst Reaction was carried out

at 80 oC during reaction the ImmPd-IL complex catalyst was filtered off and the

filtrate without addition of catalyst was allowed to react further It was found that no

further reaction occurred after this hot filtration procedure hence this experimental

finding suggests there is no palladium leaching from the ImmPd-IL complex during

the progress of a reaction In addition to reconfirm this observation ICP-AES

analysis of the reaction mixture was carried out after 15 and 3 h which revealed a

below detectable level (below 001 ppm) of palladium in solution

It is also important to study the separation and recyclability of the catalyst

The ImmPd-IL catalyst was separated from the reaction mixture by a simple filtration

procedure and was found to be effective up to four consecutive recycles for

methoxycarbonylation reaction (Figure 52) No significant decrease in yield during

recycle study was observed

Figure 52 Recycle study of ImmPd-IL catalyst

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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523 PHENOXYCARBONYLATION REACTIONS

ImmPd-IL catalytic system was further explored for the phenoxycarbonylation of aryl

iodides with various phenols to yield corresponding phenyl esters and it was observed

that corresponding products were obtained in good to excellent yields (Scheme 526)

Scheme 526 Phenoxycarbonylation of aryl iodides with phenols using ImmPd-IL

For the optimization of reaction the influence of critical parameters such as

solvent base and CO pressure on the carbonylation of iodobenzene with phenol as a

nucleophile have been investigated (Table 53 entries 1-8)

Table 53 Effect of solvents and bases on ImmPd-IL catalyzed Phenoxycarbonylation

reactiona

Entry Solvent Base CO Press

(psi)

Yield

()b

1 DMF Et3N 145 56

2 14-Dioxane Et3N 145 62

3

Water Et3N 145 0

4 Toluene Et3N 145 90

5 Toluene DBU 145 80

6 Toluene K2CO3 145 66

7 Toluene Cs2CO3 145 72

8 Toluene Et3N 73 85

a Reaction conditions Iodobenzene (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

base (3 mmol) solvent (10 mL) 8 h at 100 degC b Yield based on GC analysis

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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The role of various solvents such as NN-dimethyl formamide (DMF) (56)

14-dioxane (62) water (0) and toluene (90) was studied (Table 53 entries 1-

4) It was observed that the reaction was more favourable using toluene as a solvent

and provided 90 yield of phenyl benzoate (Table 54 entry 4) Various screened

organic and inorganic bases (K2CO3 Cs2CO3 DBU and Et3N) showed Et3N (90) to

be superior base at 100 degC (Table 53 entries 4-7) The initial reaction was carried out

at 145 psi CO pressure which provided 90 yield of phenyl benzoate a further

decrease in CO pressure up to 73 psi decreased the yield of the phenyl benzoate

(Table 53 entry 8) Hence the finalized reaction parameters were Et3N as a base in

toluene CO 73 psi at 100 degC for 8 h

These finalized reaction parameters were then applied for the

phenoxycarbonylation of different aryl halides and phenols having different electron-

donating or withdrawing groups (Table 54 entries 1-7) Iodobenzene reacts

efficiently with phenol within 8 h providing 89 isolated yield of phenyl benzoate

(Table 54 entry 1) Substituted phenols such as p-cresol p-methoxyphenol and p-

chlorophenol reacts with iodobenzene furnishing good to excellent yields of the

corresponding product (Table 54 entries 2-4) The substituted iodobenzene

derivative reacts with phenol and provided 86 yields of phenyl 4-methoxybenzoate

(Table 54 entry 5) 1-Iodo-4-nitrobenzene furnished moderate yield (59) of the

phenyl 4-nitrobenzoate (Table 54 entry 6) Reaction of 1-iodonaphthalene with

phenol provided 75 yield of phenyl 1-naphthoate (Table 54 entry 7)

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Table 54 ImmPd-IL catalyzed Phenoxycarbonylation of aryl iodides with various

phenolsa

Entry Aryl iodide Phenol Product Yield

()b

1

89

2

90

3

88

4

84

5

86

6

59

7

75

a Reaction conditions aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

Chapter 5

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

Chapter 5

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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524 AMINOCARBONYLATION REACTIONS

The scope of ImmPd-IL was further extended for aminocarbonylation of aryl iodides

with a range of aliphatic aromatic primary and secondary amines (Scheme 527)

Scheme 527 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with amines

The reaction of iodobenzene with aniline was selected as a model reaction for

optimization Various solvents such as DMF (80) water (70) anisole (60) and

toluene (92) were screened for the reaction (ionic liquid was insoluble in water as it

was immobilised on solid support) but toluene was found to be the best solvent

(Table 55 entries 1-4) Screening of a variety of bases showed Et3N (90) to be

superior at 100 degC (Table 55 entries 4-6) Further reaction was optimized with

respect to various reaction parameters including temperature time and CO pressure

and the best optimized reaction conditions were then applied for the

aminocarbonylation of a variety of iodoaryls and amines

Table 55 Effect of solvents and bases on ImmPd-IL catalyzed aminocarbonylation

reactiona

Entry Solvent Base Yield

()b

1 DMF Et3N 80

2 Water Et3N 70

3

Anisole Et3N 60

4 Toluene Et3N 92

5 Toluene Na2CO3 52

6 Toluene K2CO3 57

a Reaction conditions

Iodobenzene (1 mmol) aniline (2 mmol) ImmPd-IL (2 mol)

Et3N (3 mmol) Toluene (10 mL) 8 h at 100 degC 145 psi CO pressure b Yield based GC analysis

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

Chapter 5

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

Chapter 5

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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The optimized reaction parameters were then applied for the

aminocarbonylation of substituted aryl halides and aromatic amines The model

reaction of iodobenzene with aniline provided 90 isolated yield of N-

phenylbenzamide under optimized reaction conditions (Table 56 entry 1) 4-

iodoanisole furnished 85 yield of 4-methoxy-N-phenylbenzamide (Table 56 entries

2) 4-methoxyaniline reacts with iodobenzene and provided 88 yield of N-(4-

methoxyphenyl)benzamide (Table 56 entry 3) 3-(Trifluoromethyl)aniline provided a

moderate yield of the expected product (Table 56 entry 4)

There after various primary aliphatic amines were screened for the

aminocarbonylation Cyclohexyl amine efficiently reacts with iodobenzene and 2-

iodonaphthalene and provided 92 and 80 yield of N-cyclohexylbenzamide and N-

cyclohexyl-1-naphthamide respectively (Table 56 entries 5-6) Reaction of

iodobenzene and 4-iodo acetophenone with tert-butyl amine furnished 92 and 89

yield of respective amide (Table 56 entry 7-8) Benzyl amine provided excellent

yields of N-benzylbenzamide (Table 56 entry 9) To our delight aromatic secondary

amine such as N-methyl aniline efficiently reacts with iodobenzene furnishing 91

yield of N-methyl-N-phenylbenzamide (Table 56 entry 10)

Table 56 ImmPd-IL catalyzed aminocarbonylation of aryl iodides with various

aliphatic and aromatic primary amines and secondary aminesa

Entry Aryl iodide Amine Product Yield

()b

1

90

2

85

3

88

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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4

75

5

92

6

80

7

92

8

89

9

90

10

91

a Reaction conditions aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol )

Et3N (3 mmol) toluene (10 mL) 145 psi CO press Temp (100 degC) Time (8 h) b Isolated yield

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

Chapter 5

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

Chapter 5

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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53 CONCLUSION

The present study reports an efficient and common protocol for

alkoxycarbonylation phenoxycarbonylation and aminocarbonylation reactions

by using a well-defined heterogeneous ImmPd-IL complex as a versatile

catalyst

The ease of preparation of the complex indefinite shelf life stability towards

air makes it an ideal complex for the above transformations

The reaction system was optimized with respect to various reaction parameters

and applied for carbonylation of a range of aryl iodides with different types of

alcohols phenols and amines furnishing good to excellent yields of the

corresponding products

The present protocol provided high yields of the desired products for all

carbonylation protocols

All the reactions were carried out under milder operating conditions

Catalytic system showed excellent activity and selectivity and effectively

recycled for four consecutive cycles

The leaching of the Pd metal was examined by hot filteration test and ICP-

AES analysis which revels no significant leaching of the palladium occurs

during the reaction

Chapter 5

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239

54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

Chapter 5

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240

cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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54 EXPERIMENTAL

541 Materials and Method N-methylimidazole (99+) and 3-trimethoxysilylpropyl

chloride (97+) were purchased from Aldrich PdCl2 was purchased from WAKO

Anhydrous redistilled 1-methylimidazole (99+) was purchased from Aldrich All

the dehydrated solvents were obtained from WAKO Aerosil 300 (300 m2g) was

obtained from Japan Aerosil Co and calcined at 573 K for 15 h in air and 30 min in

vacuum before use as a support The procedures for catalyst preparation were based

previous publication (Sasaki et al 2008) with some modifications Prepared catalyst

was characterized by using IR and elemental analysis and loading of the catalyst was

calculated by XRF measurements (SEA-2010 Seiko Electronic Industrial Co) The

XPS of ImmPd-IL was measured using a PHI5000 Versa Probe with monochromatic

focused (100 times 100 μm) Al Kα X-ray radiation (15 kV 30 mA) and dual beam

neutralization using a combination of argon ion gun and electron irradiation

The products are well-known in the literature and were compared with

authentic samples Progress of the reaction was monitored by gas chromatography

(GC) Gas chromatography analysis was carried out on Perkin-Elmer Clarus 400 GC

equipped flame ionization detector with a capillary column (Elite-1 30 m times 032 mm

times 025 μm) using the external standard method A GCMS-QP 2010 instrument (Rtx-

17 30 m times 25 mm id film thickness 025 μm df) (column flow 2 mL minminus1

80-240

degC at 10 degCmin rise) The 1H NMR spectra were recorded on Varian-300 MHz FT-

NMR spectrometer in CDCl3 using TMS as the internal standard The 13

C NMR

spectra were recorded with a JEOL FT-NMR model-AL300 (75 MHz) spectrometer

in CDCl3 Chemical shifts are reported in parts per million (δ) relative to

tetramethylsilane as the internal standard J (coupling constant) values were reported

in hertz (Hz) Proton splitting patterns are described as s (singlet) d (doublet) t

(triplet) and m (multiplet)

542 Preparation of immobilized palladium metal ion-containing ionic liquid

1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was synthesized by

mixing N-methylimidazole (0690 mol) and 3-trimethoxysilylpropyl chloride (0690

mol) in a dry 300 mL flask under a nitrogen atmosphere and refluxed for 48 h After

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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cooling to room temperature the resultant liquid was washed by dehydrated ethyl

acetate five times and dried at room temperature under reduced pressure for 48 h

The obtained compound was stored at 253 K under dry nitrogen Silica (Aerosil 300

surface area 300 m2g calcined at 573 K for 15 h in air) and 1-methyl-3-(3-

trimethoxysilylpropyl) imidazolium chloride (weight ratio 11) was dispersed in

dehydrated toluene and the mixture was refluxed for 48 h under nitrogen

After the reflux toluene was removed by filtration using glass filter and the

excess ionic liquid was removed by washing with dichloromethane several times The

resultant solid is denoted as Imm-IL In the next step Imm-IL was added to an

acetonitrile solution of PdCl2 and refluxed for 24 h Acetonitrile and excess of metal

chloride were removed by washing acetone using glass filter several times The metal

loading of ImmPd-IL was 34 wt as determined by XRF measurements (SEA-2010

Seiko Electronic Industrial Co)

543 General Experimental Procedure for Alkoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) alcohol (5 mL) ImmPd-IL (2 mol )

and Et3N (3 mmol) were added The autoclave was closed purged three times with

carbon monoxide pressurized with 73 psi of CO and heated at 80 degC for 3 h After

completion of the reaction the reactor was cooled to room temperature and the

remaining CO gas was carefully vented and the reactor was opened The reactor

vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to remove any traces of

product and catalyst if present The catalyst was filtered and the reaction mixture was

evaporated under vacuum The residue obtained was purified by column

chromatography (silica gel 60-120 mesh petroleum etherethyl acetate 9505) to

afford the desired product

544 General Experimental Procedure for Recycling of ImmPd-IL

After completion of reaction the reaction mixture was cooled to room temperature

and the catalyst was collected by filtration The filtered catalyst was washed with

distilled water (3 times 5 mL) and methanol (3 times 5 mL) to remove all traces of product or

reactant present The filtered catalyst was then dried under reduced pressure The

dried catalyst was then used for the alkoxycarbonylation reaction of iodobenzene with

methanol for the recyclability experiment

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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545 XPS spectra of ImmPd-IL catalyst

The XPS spectra of ImmPd-IL shows that two peaks at 337 and 3424 eV for fresh

Imm-Pd are assigned as 3d52 and 3d32 for Pd2+

species respectively (Figure 53)

For the first recycle sample new peaks appear at 3342 and 3392 eV which are

assigned as 3d52 and 3d32 for Pd(0) species respectively indicating that the

reduction of the Pd species takes place during the catalytic reaction From the

spectrum of the fourth recycle sample it is obvious that the component of Pd2+

is

decreasing upon recycles although the component of Pd(0) remains constant

Figure 53 XPS of Pd 3d and Cl 2p for ImmPd-IL catalyst

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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546 General Experimental Procedure for Phenoxycarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) phenol (2 mmol) ImmPd-IL (2 mol )

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h After the completion of the reaction the reactor was cooled to room

temperature and the remaining CO gas was carefully vented and the reactor was

opened The reactor vessel was thoroughly washed with ethyl acetate (2 times 10 mL) to

remove any traces of product and catalyst if present The catalyst was filtered and the

reaction mixture was evaporated under vacuum The residue obtained was purified by

column chromatography (silica gel 60-120 mesh petroleum etherethyl acetate

9505) to afford the desired product

547 General Experimental Procedure for Aminocarbonylation Reaction

To a 100 mL autoclave aryl iodide (1 mmol) amine (2 mmol) ImmPd-IL (2 mol)

toluene (10 mL) and Et3N (3 mmol) were added The autoclave was closed purged

three times with carbon monoxide pressurized with 145 psi of CO and heated at 100

degC for 8 h (the ensuing procedure is the same as that discussed above for the phenoxy

carbonylation reaction)

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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55 SPECTRAL DATA

Methyl benzoate

GC-MS (EI 70 eV) mz () = 136 [M+] (35) 105 (100) 77 (55) 51 (20)

Ethyl benzoate

GC-MS (EI 70 eV) mz () = 150 [M+] (21) 122 (30) 105 (100) 77 (55)

Benzyl benzoate

1H NMR (300 MHz CDCl3) δ 804-808 (m 2H ArH) 731-752 (m 8H

ArH) 53 (s 2H CH2) 13

C NMR (75 MHz CDCl3) δ 16648 13619 13312

13025 12981 12870 12848 12834 12827 6677

Methyl 4-aminobenzoate

1H NMR (300 MHz CDCl3) δ 783 (d 2H J = 87 Hz ArH) 661 (d 2H J =

87 Hz ArH) 414 (br s 2H NH2) 383 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16724 15107 13151 11927 11368 5155

Methyl 4-hydroxybenzoate

1H NMR (300 MHz CDCl3) δ 794 (d 2H J = 87 Hz ArH) 722 (br s 1H

OH) 690 (d 2H J = 87 Hz ArH) 390 (s 3H OCH3) 13

C NMR (75 MHz CDCl3)

δ 16778 16055 13203 12201 11539 5223

Methyl 2-naphthoate

1H NMR (300 MHz CDCl3) δ 850 (s 1H ArH) 798-805 (m 2H ArH)

773 (t 2H J = 84 Hz ArH) 754-761 (m 2H ArH) 396 (s 3H OCH3) 13

C NMR

(75 MHz CDCl3) δ 16685 13634 13087 13082 13013 12938 12901 12778

12720 12632 12260 5235

Ethyl 4-acetylbenzoate

1H NMR (300 MHz CDCl3) δ 814-811 (m 2H ArH) 802-799 (m 2H

ArH) 441 (q 2H J = 69Hz CH2CH3) 265 (s 3H COCH3) 142 (t 3H J = 69Hz

CH2CH3) 13

C NMR (75 MHz CDCl3) δ 19766 16576 14012 13424 12977

12817 6147 2689 1427

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Phenyl benzoate

1H NMR (300 MHz CDCl3) δ 825-822 (m 2H ArH) 768-863 (m 1H

ArH) 756-742 (m 4H ArH) 732-723 (m 3H ArH) 13

C NMR (75 MHz CDCl3)

δ 16590 15103 13365 13023 12964 12956 12864 12596 1217 GC-MS (EI

70 eV) mz () = 198 [M+] (9) 105 (100) 77 (40) 51 (9)

phenyl 4-nitrobenzoate

1H NMR (300 MHz CDCl3) δ = 837 (s 4H ArH) 723-748 (m 5H ArH)

13C NMR (75 MHz CDCl3) δ = 16347 15110 15072 13517 13144 12984

12657 12388 12157 GC-MS (EI 70 eV) mz () = 243 [M+] (15) 150 (100) 77

(10)

phenyl 4-methoxybenzoate

1H NMR (300 MHz CDCl3) δ = 814-816 (d 2H J = 87Hz ArH) 720-741

(m 5H ArH) 696-698 (d 2H J = 87 Hz ArH) 386 (s 3H OCH3) GC-MS (EI

70 eV) mz () = 228 [M+] (5) 135 (100) 107 (9) 77 (20)

phenyl-1-naphthoate

1H NMR (300 MHz CDCl3) δ = 904 (d 1H ArH) 845 (d1H ArH) 804

(d 1H ArH) 788 (d 1H ArH) 742-763 (m 5H ArH) 726-728 (m 3H ArH)

13C NMR (70 MHz CDCl3) δ = 16594 15118 13440 13408 13182 13134

12968 12883 12850 12829 12650 12605 12590 12465 12203

N-phenylbenzamide

1H NMR (300 MHz CDCl3) δ 798 (br s 1H NH) 787-883 (m 2H ArH)

763 (d 2H J = 76 Hz ArH) 732-753 (m 5H ArH) 716 (t 1H J = 73 ArH) 13

C

NMR (75 MHz CDCl3) δ 16590 13798 13502 13186 12911 12880 12709

12461 12032 ppm GC-MS mz () = 197 [M+] (42) 105 (100) 77 (54)

4-acetyl-N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 806 (d 2H J = 84Hz ArH) 777 (d 2H J

= 84Hz ArH) 601 (br s 1H NH) 393 (s 3H CH3) 148 (s 9H) 13

C NMR (75

MHz CDCl3) δ 16640 16605 13987 13234 12979 12682 5239 5195 2883

ppm GC-MS (EI 70 eV) mz () = 219 [M+] (20) 186 (22) 148 (100) 130 (30) 76

(20)

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

Chapter 5

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

Chapter 5

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

Chapter 5

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

Chapter 5

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

Chapter 5

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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N-benzylbenzamide

1H NMR (300 MHz CDCl3) δ 799-776 (d 2H J = 73 Hz ArH) 740-729

(m 8H ArH) 670 (br s 1H NH) 459 (d 2H J = 57 Hz CH2) 13

C NMR (75

MHz CDCl3) δ 16748 13830 13441 13157 12879 12860 12791 12759

12706 4411 GC-MS (EI 70 eV) mz () = 211 [M+] (11) 210 (68) 209 (30) 105

(100) 91 (11) 77 (69) 51 (12)

N-cyclohexylbenzamide

1H NMR (300 MHz CDCl3) δ 777-774 (m 2H ArH) 736-746 (m 3H

ArH) 618 (br s 1H NH) 397-394 (m 1H CH) 203-198 (m 2H CH2) 177-161

(m 3H CH2) 143-115 (m 5H CH2) 13

C NMR (75 MHz CDCl3) δ 16669 13511

13122 12849 12691 4873 3321 2558 2498 GC-MS (EI 70 eV) mz () =

203 [M+] (29) 122 (75) 105 (100) 79 (15) 77 (52)

N-(tert-butyl)benzamide

1H NMR (300 MHz CDCl3) δ = 768-771(m 3H ArH) 735-744 (m 3H

ArH) 595 (br s 1H NH) 145 (s 9H CH3) 13

C NMR (75 MHz CDCl3) δ 16694

13595 13109 12849 12672 5162 2890 ppm GC-MS (EI 70 eV) mz () =

1779 [M+] (20) 162 (22) 122 (18) 105 (100) 76 (20)

N-methyl-N-phenylbenzamide

GC-MS (EI 70 eV) mz () = 211 [M+] (25) 118 (9) 105 (100) 77 (60) 51

(15)

Chapter 5

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

Chapter 5

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

Chapter 5

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

Chapter 5

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

Chapter 5

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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551 SPECTRAS

Figure 54 GC-MS spectrum of Methyl benzoate

Figure 55 GC-MS spectrum of Ethyl benzoate

Chapter 5

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

Chapter 5

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

Chapter 5

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

Chapter 5

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 56 1H NMR (300 MHz) spectrum of Benzyl benzoate

Figure 57 13

C NMR (75 MHz) spectrum of Benzyl benzoate

Chapter 5

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

Chapter 5

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

Chapter 5

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 58 1H NMR (300 MHz) spectrum of Methyl 4-aminobenzoate

Figure 59 13

C NMR (75 MHz) spectrum of Methyl 4-aminobenzoate

Chapter 5

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

Chapter 5

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 510 1H NMR (300 MHz) spectrum of Methyl 4-hydroxybenzoate

Figure 511 13

C NMR (75 MHz) spectrum of Methyl 4-hydroxybenzoate

Chapter 5

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Figure 512 1H NMR (300 MHz) spectrum of Methyl 2-naphthoate

Figure 513 13

C NMR (75 MHz) spectrum of Methyl 2-naphthoate

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

Chapter 5

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 514 1H NMR (300 MHz) spectrum of Ethyl 4-acetylbenzoate

Figure 515 13

C NMR (75 MHz) spectrum of Ethyl 4-acetylbenzoate

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 516 1H NMR (300 MHz) spectrum of Phenyl benzoate

Figure 517 13

C NMR (75 MHz) spectrum of Phenyl benzoate

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 518 GC-MS spectrum of Phenyl benzoate

Figure 519 1H NMR (300 MHz) spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

Chapter 5

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 520 13

C NMR (75 MHz) spectrum of Phenyl 4-nitrobenzoate

Figure 521 GC-MS spectrum of Phenyl 4-nitrobenzoate

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

Chapter 5

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 522 1H NMR (300 MHz) spectrum of Phenyl 4-methoxybenzoate

Figure 523 GC-MS of Phenyl 4-methoxybenzoate

Chapter 5

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 524 1H NMR (300 MHz) spectrum of Phenyl 1-Naphthoate

Figure 525 13

C NMR (75 MHz) spectrum of Phenyl 1-Naphthoate

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 526 1H NMR (300 MHz) spectrum of N-phenylbenzamide

Figure 527 13

C NMR (75 MHz) spectrum of N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 528 GC-MS spectrum of N-phenylbenzamide

Figure 529 1H NMR (300 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 530 13

C NMR (75 MHz) spectrum of 4-acetyl-N-(tert-butyl)benzamide

Figure 531 GC-MS spectrum of 4-acetyl-N-(tert-butyl)benzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

Chapter 5

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

Chapter 5

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

Chapter 5

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

Chapter 5

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Figure 532 1H NMR (300 MHz) spectrum of N-benzylbenzamide

Figure 533 13

C NMR (75 MHz) spectrum of N-benzylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Figure 534 GC-MS spectrum of N-benzylbenzamide

Figure 535 1H NMR (300 MHz) spectrum of N-cyclohexylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Figure 536 13

C NMR (75 MHz) spectrum of N-cyclohexylbenzamide

Figure 537 GC-MS spectrum of N-cyclohexylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Figure 538 1H NMR (300 MHz) spectrum of N-(tert-butyl)benzamide

Figure 539 13

C NMR (75 MHz) spectrum of N-(tert-butyl)benzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide

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Figure 540 GC-MS spectrum of N-(tert-butyl)benzamide

Figure 541 GC-MS spectrum of N-methyl-N-phenylbenzamide