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1
SCHOOL OF SCIENCE AND HUMANITIES
DEPARTMENT OF CHEMISTRY
UNIT – 1 ORGANIC REAGENTS - I – SCY1620
2
1. ORGANIC REAGENTS – I
Introduction to Organic Reagents, Types of Reagents, Oxidation Reagents, DDQ, SeO2,
KMnO4,OsO4 , Epoxidation of Olefins ,Jones Reagent, Oppenauer Oxidation, HIO4.
KMnO4
1. cis Hydroxylating agent
KMnO4
OH
OH
KMnO4
OH
OH
KMnO4
OH
OH
OOH
OOHOH
OH
KMnO4
OOHOH
O
OOHO
OH
+
+
Potassium permanganate will attack on double bond which is having less steric hinderance.
KMnO4
OH
OH
C6H6
KMnO4
OO
OH
[18 crown -6]
OH
OH
O
O
KMnO4
3
OsO4
O
OH
OsO4
pyridine
O
OHOH
OH
OsO4, ether, Pyridine
OH
OH
OH
OH K3[Fe(CN)6]
OH
OH
O
O
OsO4, ether, Pyridine OH
OH
O
O
O
O
KClO3, OsO4
Ether, Pyridine
O
O
O
O
OH
OH
OOH H2O2
OsO4, KClO3
OOHOH
OH
OHOsO4
ETHER, NMO
OH
OH
OH
OsO4
TBHP, t-Bu-OH, Et4NOH
OH
OH
O
O
+
OsO4, NaIO4
dioxane, H2O
N
OO
NH
H
H
N
OO
OH
OH N
OO
O
Prepared by Dr K> CHENNAKESAVULUDept. of ChemistrySIST, CHENNAI
N
OO
OH
OH
OsO4, NaIO4
OsO4, ether, Pyridine
OH
OH
OH
OH K3[Fe(CN)
6]
OH
OH
O
O
OsO4, ether, Pyridine OH
OH
4
Epoxidation of olefins
OO
O H
O
OH
HO
OH
R1
Cl
O OH
Cl
O O OH
m-chloro benzoic acidm-chloro perbenzoic acid (mcPBA)
PAA (Peroxy acetic acid)H2O2 Alkyl peroxide
Epoxides and their nomenclature
O
oxirane
EPOXY ETHANE
O 1,2 EPOXY PROPANE
2-methyloxirane
O2,3 EPOXY BUTANE
2,3-dimethyloxirane
O 1,2 EPOXY CYCLO HEXANE
7-oxabicyclo[4.1.0]heptane
5
Epoxidation of olefins
O
OHOH
O O OH
PBA
O
OHOH
O O OH
PBA
SYN EPOXIDE
HH
H
H
PBAO
O
+
Major
Minor
O
PBA
PBA
O
PAAO
PAA
O
6
JONES REAGENT
OH CrO3, CH
3COCH
3, H
2SO
4
O
OHCrO
3, CH
3COCH
3, H
2SO
4O
HIO4
H OH
H OH HIO4
O
H
2
H O
H O
H
H
I
O
O–
OH
OH
OH
OH
+H
H
I
O
O
OH
OH
O
OH
H
H
I–
O
O
O–
OH
O
O
O
H
2
7
DDQ
O
O
Cl
Cl
CN
CN
H H
DDQC
+
H
H
H
C+
HH
H
H
H
H HH
H
O
O
Cl
Cl
CN
CN
O–
OH
Cl
Cl
CN
CN
C+
H
H
H
O
O
Cl
Cl
CN
CN
H H
DDQ
HH
Ph
H Ph
O
O
Cl
Cl
CN
CN
PhC
+
Ph
PhPh
OH
O
O
Cl
Cl
CN
CN
OO
OOH
O
OH
O
O
Cl
Cl
CN
CN
OOH
O
O
O
O
Cl
Cl
CN
CN
O
OH
OHO
8
O
O
OH
Ph
C6H6
DDQ
O
O
O
Ph
O
C6H
6
DDQ
O
CH+ ClO 4
-
O
Ph
Ph
PhH
DDQ
C6H6, H3O+
DDQ
HClO4, AcOH
C+
Ph
Ph
Ph
ClO 4
-
O
H DDQ
AcOH O
PhO
O
DDQ
AcOH
OH
O
O
2
DDQ
CH3OH
O
O
O
O
O
O
OH
H
DDQ
HClO4, AcOH
O
9
SeO2
SeO2
OH
OH
+
SeO2
OH
NSeO2
N
OH
N SeO2 NO
H
SeO2
O H
O
+
OH
OH
+
OHOH
OH
OH
Ether , Pyridine
OsO4
O
Ether , Pyridine
OsO4O
OH
OH
Prepared by Dr K> CHENNAKESAVULUDept. of ChemistrySIST, CHENNAI
10
SCHOOL OF SCIENCE AND HUMANITIES
DEPARTMENT OF CHEMISTRY
UNIT – 1 ORGANIC REAGENTS - II – SCY1620
11
1. ORGANIC REAGENTS – II
Reducing Agents , Hydride ion transfer mechanism, Electron Transfer mechanism LAH, NaBH4,
Electrophilic Reducing Agents, Allanes and Boranes, Hydroboration, Dissolving metal reduction,
Birch Reduction, Clemmensen Reduction, Wolf-Kishner Reduction Lindlars Reagent.
A Z
H H
REDUCING AGENTS
HYDRIDE TRANSFER ELECTRON TRNASFER
A Z
H-
A Z
HH
3O+
A Z
H H
A Z
A Z
A Z
A Z
H
H+
electron from reducing agent
electron from reducing agent
A Z
HH+
LAH FUNCTIONS
ACID HALIDESESTERSANHYDRIDESEPOXIDESACID
ALCOHOLS
AMIDESNITRILESAZIDESNITROIMINES
AMINES
HALOCOMPOUNDSSULPHONATES
HYDROCARBONS
12
LAH MECHANISM
O OH + Al(OH)34
Al–
H H
H H
Li+
O4
Al–
H H
H H
Li+
O– Al
H H
H
O
Al–
H
H H
OO–
O
Al–
H
H H
O
Al–
H
H H
O
Al–
H
H O
O
Al–
H
H O
O
O–
O
Al–
H O
H
O
O
Al–
H O
O
O
Al–
H O
O
O
Al–
OO
O
OH + Al(OH)34
13
LAH CHEMICAL REACTIONS
O
OH
H OH
H
+
O
CH3
CH3
CH3
MAJOR MINOR
OH
H
CH3
CH3 CH3
OH
H
CH3
CH3
CH3
+
MINORMAJOR
ENDO EXO
CH3
CH3
CH3
O
LAH
CH3
CH3 CH3
OH
H
CH3
CH3
CH3
H
OH+
MINORMAJOR
LAH
LAH
O
H
OH
H
OH
H
LAH, RT, ETHER, H3O+
LAH, 0 TO 5o C, ETHER,
H3O+
O
O
LAH
OH
OH
CH4
N
O
LAH N
N
OLAH
N
N OH
LAH
N
Br
LAH
O
N
O
H
NH
+
14
NaBH4
NH2
O
O
H
Na+
B–
HH
H H
NH2
O
H
OH
O
OO
Li+
Al–
HH
H H
O
OOH
Na+
B–
HH
H H
OH
OH
OH
OH+
O
OO O
LAH
OH
O O
OH
O
O
OO
O
OH
H OH
H
+
O
CH3
CH3
CH3
MAJOR MINOR
OH
H
CH3
CH3 CH3
OH
H
CH3
CH3
CH3
+
MINORMAJOR
ENDO EXO
CH3
CH3
O
CH3 CH3
OH
H
CH3
CH3
H
OH+
MINORMAJOR
NaBH 4
NaBH 4
ENDO APPROACH
EXO APPROACH
NaBH 4
O
CH3
CH3
OH
H
CH3 CH3
OH
H
CH3
CH3
+
MINORMAJOR
NaBH 4
15
AlH3 and BH3
AlH3 and BH3
CarbonylEsterAcidsAcid halidesAcid anhydridesepoxides
Alcohols
AmidesNitrilesinaminesIsocyanates
Amines
O
N
AlH3
Et2O
N
O
ClAlH3
Et2O
OH
AlH3 and BH3
Ph3P
AlH3
Cl Cl
O
AlH3
OH
N
O
N+
O–
O
AlH3
NH2
N+
O–
O
NH
O
AlH3 NH
16
BH3
N+ O
–O
OOH
B2H6
N+ O
–O
OH
N+ O
–O
O
B2H6
N+
O–
O
O
B
H
H
H
N+
O–
O
O
B
H
H
N+ O
–O
O
N+
O–
O
O
B
H
O
N+
O–
O
N+ O
–O
O
N+
O–
O
O
B
O
O
N+
O–
O
N+ O
–O
H3O+
N+
O–
O
OH
OH
N+ O
–O
OH
N+
O–
O
BH3
OHO
OO
O
BH3
O
O
O
O
BH3
O
O
BH3
17
Wolf Kishner Reduction
O N N
H
H
H
H
N N
H
H
OH-
N N–
H
C–
N N
H
H+
N N
HH
C–
H
H+
H
H
O
N2H
4, NaOH
ON
2H
4, NaOH
O
O
N2H
4, NaOH
O
18
Birch Reduction
Na, Liq Ammonia
Na, Liq Ammonia
NNH
Na, Liq Ammonia
O
OO
O
OO
O
B.R
OH OH
+
Major Minor
O O
H
HO
H
H
+
Major
B.R
B.R
19
The effect of electron donating and withdrawing groups on Birch Reduction (B.R.)
O OH OH
OHO OH OHO OH
N+ O
–O
N+
O–
O
B.R B.RB.R
FORMS NOT FORMSFORMS FORMS FORMS NOT FORMS
N+ O
–O
N+O
–
O
N+
O–
O
B.RB.R
FORMSFORMS
20
SCHOOL OF SCIENCE AND HUMANITIES
DEPARTMENT OF CHEMISTRY
UNIT – 3 ORGANIC REAGENTS - III – SCY1620
21
3. ORGANIC REAGENTS - III
Introduction to organo-metallic reagents, Grignard reagent, Gilman’s reagent, LDA, 1, 3
dithianes, Wittig Reagent, Peterson olefination
Gilman’s Reagent
Preparation:
CuI + CH3Li CH3Cu + LiI
CH3CU + CH3Li (CH3)2CuLi
Cl
+ (CH3)2CuLi + CH3Cu + LiI
Ph
I
+ (CH3)2CuLi
Ph
CH3Cu + LiI
+
Reactions
Br
Br
(CH3)2CuLi
BrO
(CH3)2CuLi
O
O
O
O OHH
(CH3)2CuLi
22
Gilman’s Reagent Reactions
O
O(CH
3)2CuLi
O
OH
OTs
(CH3)2CuLi
O
(CH3)2CuLi
O O
+
O O O
+(CH
3)2CuLi
OO
(CH3)2CuLi
O
23
Grignard Reagents
MgCl
+ MgCl(OH)H
2O
D2O
D
ROH
RNH2
MgCl(NHR)+
MgCl(OR)+
MgCl(OD)+
MgCl
MgCl
MgCl
MgCl(COOR)+
MgCl
RCOOH
MgCl(SR)+
MgCl
RSH
MgCl(C2H)+
MgCl
C2H
2
24
ESTERSAMIDESACID HALIDESNITRILES
1 eq of RMgX
2 eq of RMgX
Alcohol
Carbonyl Compounds
O
O
Excess of RMgX
OH
RR OH
OPhMgX
OH
Ph
O
EtMgBr
OH
BH3
BH2
H2O, CO, OH-
O
H
OCH
3MgI O
CH4
Wittig Reagent: Conversion of carbonyl compounds to olefines by using phosphoranes or
phospharus ylides called wittig reaction.
O + (Ph)3P=CH2 + (Ph)3P=O
P+
Ph
Ph
Ph
CH2
–
PEtO
EtO
CH2
–
O
Li+
O
+ P+
Ph
Ph
Ph
CH2
–
YLIDE
25
P+
Ph
Ph
Ph
CH2
–
O
+
Li+
OH
P
PhPh
Ph
Ph - CHO
OH
Ph
O
CH3MgBr
OH
Con. H2SO4+
Major Minor
OP
+Ph
Ph
Ph
CH2–
O
H H
Witting Reagent
OP
+Ph
Ph
Ph
C–
O
H
OLi
+
O
C O + P+
Ph
Ph
Ph
CH2
–
C
26
P+
Ph
Ph
Ph
CH2
–
O
+
Li+
OH
P
PhPh
Ph
Ph - CHO
OH
Ph
O
CH3MgBr
OH
Con. H2SO4+
Major Minor
OP
+Ph
Ph
Ph
CH2–
O
H H
Witting Reagent
OP
+Ph
Ph
Ph
C–
O
H
OLi
+
O
C O + P+
Ph
Ph
Ph
CH2
–
C
27
Peterson’s olefination
Conversion of carbonyl compound into olefines by using lithio or magneisio derivates of silyl
compounds called peterson's olefination.
O + Si C–
HLi
+
O
+ Si C–
H
Cl
O–
Si
H
Cl
O
Si
H
O
Si
H
O
H
28
LDA
N–
Li+
+
O
CH–
O
CH–
O
+
N–
Li+
+
O
C–
O
CH–
O
+
O +LDA
C–
O
CH–
O
1:1 YIELD
MINOR
MAJOR
+
MINORMAJOR
N–
Li+
+
O
CH–
O
O
N–
Li++
O
CH2–
+ CH3Cl
OCH4
29
UMPOLOUNG REACTION OR 1,3 DITHIANES
O
HSHSH
+
C
SS
CH3H
nBu Li
C–
SS
CH3
+ C2H
5 Cl
C
SS
CH3
C
CH3
O
SHSH
+
O
H
H
SHSH
+
C
SS
H H
nBu Li
C–
SS
H
+ CH3Cl
C
SS
CH3H
C
CH3
O
SHSH
+nBu Li
C–
SS
CH3
CH3Cl
Acetaldehyde to ethyl methyll ketone conversion
Formalaldehyde to Acetone conversion
30
Benzaldehyde to acetophenone conversion
O
HSHSH
+ SS
H
nBu Li
C–
SS + CH3Cl
O
SHSH
+
O
H
H
SHSH
+
C
SS
H H
nBu Li
C–
SS
H
+ CH3Cl
C
SS
CH3H
C
CH3
O
SHSH
+nBu Li
C–
SS
CH3
CH3Cl
31
SCHOOL OF SCIENCE AND HUMANITIES
DEPARTMENT OF CHEMISTRY
UNIT – 4 GREEN CHEMISTRY – SCY1620
32
4. GREEN CHEMISTRY
Need - principles - planning of green synthesis, Examples of green reactions - Importance
and experimental conditions required, Green reactions in condensation, oxidation, reduction,
rearrangement and addition reactions Microwave assisted reactions, solid state synthesis and
ionic liquid reaction.
GREEN CHEMISTRY
IT IS AN APPROACH TO DESIGN, MANUFACTURE BY ELIMINATING CHEMICAL HAZARDS.
Benfits of Green Chemistry1. Economical2. Energy efficient3. Lowers the cost of production4. Less waste5. Fewer accidents6. Safer products7. Healthier work place and environment8. Protect human health and environment9.Competitive Advantage
12 Principle1. PREVENTION 2. ATOM ECONOMY3. LESS HAZADOUS CHEMICALS4. DESIGNING THE SAFER CHEMICALS5. SAFER SOLVENTS AND AUXILARIES6. DESIGN FOR ENERGY EFFICIENCY7. USE OF RENEWABLE RESOURCES8. REDUCE THE DERIVATES9. CATALYSIS10.BIODEGRADABILITY11. REAL TIME ANALYSIS FOR POLLUTION PREVENTION12. SAFER CHEMISTRY FOR ACCIDENT PREVENTION
33
ACYLATION IN IONIC LIQUIDS
O
+
ClOO
O
O
O
+
96% 4%
GREEN CHEMISTRY
Copper triflate in bmimBF4
O
+
ClOO
O
O
O
+
Acetonitrile
93%7%
64%
CONDENSATION REACTION IN IONIC LIQUIDS
H
O
NaOH aq/ Solvent/reflux for 3hours CH–
H
O
H
O
+
H
H
H
O
OH
H
H
H
O
H
O
NaOH aq/ Solvent/reflux for 3hours
H
O+
CH–
H
O
H
O
C–
H
OH
O
H
O
H
H
H
O
H
H
H
O+
Product (B)
A
PRODUCT A
1
2
3
4
1
3
Aldol condensation
Cross Aldol condensation
H
O
34
WITTIG REARRANGEMENT IN IONIC LIQUIDS
Witting Rearrangement
O H
+ (Ph)3P=CH(COCH3)
(CH3CO)HC H
Ph3PO+
Chromatography or crystallization
in presence of Ionic liquid
1-butyl-3-methylimidazolium tetrafluoroborate or bmimBF4
O H
+ (Ph)3P=CH(COCH3)
(CH3CO)HC H
Ph3PO+
solvent
bmimBF4 EXTRACTION CAN BE DONE WITH TOLUENE
THE SAME IONIC LIQUID CAN BE REUSED.1 USE = 82%2ND USE= 83%6TH USE = 91%
DIESALDER REACTION IONIC LIQUIDS
+
O
O
O
O
H
O
O
H
+
Endo product Exo product
emim Cl/(AlCl3) - (48% AlCl3)
basic , 22 hours
Yield = 32%Endo/Exo = 4.88
emim Cl/(AlCl3) - (51% AlCl3)
Acedic , 22 hours
Yield = 53%Endo/Exo = 19
emim Cl/(AlCl3) - (48% AlCl3)
basic , 72hours
Yield = 95%Endo/Exo = 5.28
emim Cl/(AlCl3) - (51% AlCl3)
Acedic , 72 hours
Endo/Exo = 19 Yield = 79%
35
SCHOOL OF SCIENCE AND HUMANITIES
DEPARTMENT OF CHEMISTRY
UNIT – 5 INTRODUCTION TO PERICYCLIC REACTIONS – SCY1620
36
4. INTRODUCTION TO PERICYCLIC REACTIONS
Pericyclic reactions are concerted reactions.
The characteristics of pericyclic reactions
1. It is single step reaction
2.There is no reactive inetermidiate.
3. It forms transition state
4. Simultanious bond formation and bond breaking
5. These are synchronus concerted reactions
6. These are common in olefinic system
7. There reactions are controlled by either heat or light
8. These are kinetically controlled reactions
SN1 reaction in high polar solvents is very fast
SN1 Reacion in low polar solvents is very slow
Energy profile diagram of pericyclic reactions
CH
CH2
CH
CH2
REACTION PATH
ENERGY
TRANSITION STATE
37
Classification of electrocyclic reactions
1. Electrocyclic reaction
2. Cyclo addition reaction
3. Sigma tropic reactions
4. Chelotropic reaction
5. Group transfer reaction
FMO ORBITALS OF ETHYLENE
Y2
BMO
ABMO
NODES= 1
NODES= 0
FMO ORBITALS OF 1,3 BUTADIENE
Y1
Y2
Y3
Y4
HOMO
LUMO
NODES=0
NODES=1
NODES=3
NODES=2
38
FMO ORBITALS OF 1,3,5 HEXATRIENE
Y1
Y2
Y3
Y4
Y5
Y6
HOMO
LUMO
NODES = 1
NODES = 0
NODES=2
NODES=3
NODES=4
NODES=5
39
Cyclo Addition Reaction Mechanism Thermal Approach:
Cycloaddition of ethylene + ethylene thermally SUPRA-ANTRA OR ANTRA-SUPRA
addition is allowed.
Cycloadditon of ethylene + ethylene photochemically SUPRA-SUPRA OR ANTRA –
ANTRA addition is allowed.
Y2
+
BMO
ABMO
Y1
A-S
S-S
Y1
Y2
Y2
Y1
S-A
Y2
A-A
Y2
Y2
BMO
ABMO
Y1
NOT ALLOWED
ALLOWED
THERMAL APPROACHPARTICIPATING LUMO
PARTICIPATING
HOMO
HOMO
LUMO LUMO
LUMOLUMO
HOMO
HOMOHOMO
Cyclo Addition Reaction Mechanism Photochemical Approach:
Y2
+
BMO
ABMO
Y1
S-S
S-A
Y2
Y1
A-A
Y2
A-S
Y2
Y2
BMO
ABMO
Y1
NOT ALLOWED
ALLOWED
PHOTO CHEMICAL APPROACH
PARTICIPATING LUMO
PARTICIPATING
LUMO BECOMES HOMO
HOMO
LUMO LUMO
LUMOLUMO
HOMO
HOMOHOMO
40
CYCLOADDITION REACTIONS EXAMPLES:
+
4p + 2p
O +
O
6p + 4pO
+CH2CH2
CH2 CH2
+
2p + 2p
O
O
O+
O
O
O
4p + 2p
41
+
SIGMATROPIC REARRANGEMENTS
Substituent
H
1,3 sigmatropic Rearrangement
Substituent
Substituent
Substituent
Substituent
[1,5] sigmatropic shift
[1,3 sigmatropic shift
Substituent
Substituent
Substituent
H
42
CHELOTROPIC REACTIONS
C
H H
+
+
SOO
SOO
43
ELECTRO CYCLISATION REACTION MECHANISM OF 1,3 BUTADIENE:
Electro cyclisation of 1,3 butadiene is thermally allowed
Electro cyclisation of 1,3 butadiene is photo chemically allowed.
Y2
Y3
HOMOLUMO
+
Δ
CON ROTATION
allowed
not allowed
CON ROTATIONDIS ROTATION
DIS ROTATION
Participating orbital Participating orbital
PHOTO CHEMICAL APPROACHTHERMAL APPROACH
hν
hνΔ
not allowed
44
Electro cyclization of 1,3,5 hexatriene – Thermal approach
ΔCON ROTATION
DIS ROTATION
NOT ALLOWED
ALLOWED
1,3,5 HEXA TRIENE
Y3
PARTICIPATING ORBITAL IS HOMO
Electrocyclization of 1,3,5 hexa triene – Photo chermal approach
Y4
CON ROTATION
hν
DIS ROTATION
hν
1,3,5 HEXA TRIENE
PARTICIPATING ORBITAL NOT ALLOWED
ALLOWED