PAPER CHEMISTRY 2013

Chemistry Paper: C

Time Allowed: 3 Hrs. Max. Marks: 50

Note: Attempt FIVE questions. All questions carry equal

marks.

Q. Fumaric and maleic acids are geometrical isomers. How can they be converted into each other? How

these acids can be differentiated? 2

Q. Explain the following term with examples. 4

(i) Dihedral angle (ii) Epimer (iii) Enatiomer (iv) Racemate

3. Identify the stable geometrical isomers of the following compounds with justification: 4

i. 1,2-Dimethylcyclohexane

ii. 1,3-Dimethylcyclohexane

iii. 1,4-Dimethylcyclohexane

iv. Decaline

Q. Devise a synthesis of aspirin from phenol. Show all the steps. 2

Q. Describe simple chemical tests to. distinguish between: 4

Methoxymethane and methyl iodide

Ethoxyethane and ethanol

Methoxypropane and 1-pentene

Methoxybenzene and methylbenzene

Q. Explain with mechanisms the reactions of benzaldehyde with: 3x2

Sodium cyanide in aqueous ethanol.

Sodium hydroxide (50% aqueous solution)

Q. How would you convert benzaldehyde into the following compound? Describe the mechanisms of the

reactions involved: 4

(i) Styrene (ii) 3-phenylpropenal

Q. Draw the Structure for the following compounds and labeled with their systematic 1UPAC names:

10

1) Acetonitrile (2) Acetamide (3) Acetic acid (4) Acetaldehyde (5) Acetanilide (6) Acetone (7) Acetylene

(8) Ally alcohol (9) Aspirin (10) Acetophenone

Q. What do you know about Hoffmann and Sytzeff rules? Explain with examples. 6

Q. Account for the following observation. 4

The reaction of 2-bromopropane with sodium ethoxide in ethanol leads to propane as a major product and

ethoxypropane as minor product whereas with EtSNa in ethanol provides ethyl isopropyl sulfide as a major

product and propene as minor product.

Q. Hydrolysis of methyl chloride is catalyzed by the addition of sodium iodide whereas the hydrolysis of

2,2-dimethylethyl chloride is retarded by the addition of sodium chloride.

Neopentyl bromide is notoriously slow to both SN1and SN2 reactions.

Both sodium cthoxide and ethanol react with tert-butyl chloride with the same reaction rate although sodium

ethoxide is a better nucleophile than ethanol.

Q. What is hydrogen bonding? Differentiate between Intra-molecular and Intermolecular hydrogen bonding

with suitable examples. 4

Q. Explain Inductive effect. Resonance effect, steric effect and Hydrogen bonding and discuss their effects

on acid - base strength of organic molecules. Decorate your answer with examples. 10

Q. How will you prepare the three isomeric nitrobenzoic acids from toluene? 3

Q.Design a suitable scheme for the synthesis of phenanthrene from naphthalene. Show all the-steps . 3

What is aromaticity? Describe the criteria to declare a compound aromatic. 4

Q.Draw the conformational energy diagram of n-butane for a complete rotation of 360° about central C-C

bond and indicate the relative energies of the potential conformations. 2.5

Q. Chirality is the result of asymmetry and whether a molecule is symmetric or asymmetric can be

determined from the presence or absence of certain elements of symmetry.

Q. Draw Fisher projections for all the stereoisomers of 2,3.4-trihydroxypentanoic acid and label each chiral

carbon atom as R or S.

a) Describe at least four methods for the conversion of benzene into phenol. 6

b) Show how each of the isomeric pentyl alcohols will behave towards Iodoform and Lucas tests.4

Q. Outline the reactions along with mechanisms for the conversion ofcyclohexanone into:5x2

(i) Cyclohexane (ii) cyclohexenc (iii) cyclohexane-1,2-dione (iv) Adipic acid (v) Caprolactone

Q. Hunsdiecker and Kochi reactions are complimentary to each other. What are these reactions? Explain

with reactions equations. 4

Q. Write down the mechanisms for acid and base catalysed hydrolysis of an ester. 2

Q. Write down the reaction equations with reaction conditions for the conversion of Hexanamide into

Hexanamine, Pentanamine, Hexanenitrile and Hexanoic acid. 4

Q. Outline the Hantzsch Syntheses of Pyridine and Pyrrole with mechanisms. 5

Q. Describe the importance of arenediazonium salts in organic synthesis. 5

Q. Write a short note on the following: 3+3+4

(a) Crown ethers (b) Hydroboration (c) Reductive amination

Q. What do you know about hybridization of atomic orbitals of carbon atoms in alkanes, alkenes, alkynes

and arenes? Explain with examples. 2x5

Q. Give brief description of hybridization of orbitals of nitrogen, oxygen and sulfur atoms in various

functional groups.

Q. Outline three different methods with equations for the synthesis of alkenes. 3

Q. How toluene can be converted into three isomeric nitrobenzoic acids? Show only reaction equations

3

Q. Design a suitable scheme for the Synthesis of naphthalene from benzene. Show all the steps. 2

Q.Drawthe conformational energy diagram of n-butane for a complete rotation of 360° about central C-C

bond and indicate the relative energies ofthe potential conformations. 3

Q. Describe optical isomerism in cyclohexanes 3

Q. Give various methods for the determining the configuration of geometrical isomer? 4

Q. Discuss the effects of various factors on the mechanism and rate of nucleophilic substitution reactions.

10

Q. Primary, secondary and tertiary alcohols can be differentiated using different chemical tests. Describe

these tests and explain with chemical equations. 5+5

Q. Outline the syntheses of acetophenone

(i) from benzonitrile 2) from phenylacetylene. 2

Q.Reduction of aldehydes and ketones to hydrocarbon can be carried out either by Clemmensen reduction or

Wolff-Kishner reduction. Describe the mechanisms of these reductions. 4

Q. Outline the synthetic applications of ethyl acetoacetate. 8

Q. Write down the mechanisms for acid and base catalysed hydrolysis of an ester 2

Q Write reason(s) briefly: (2+1+1+2+2)

I. pka value of ETHANOL is higher than that of PHENOL.

II. The enolic content of ACETOACETIC ESTER in water is 0.4%while in toluene 20%.

III. Iodine is the least reactive towards alkanes.

IV. 2-Butene is more stable than 1-Butene.

V. 2,3-Dichlorobutane possesses only .THREE stereoisomers instead of FOUR

Q. Explain the term "CRACKING" and describe its utility. (2)

Q How would you bring out the following conversions? (12+2)

i) 1-Pentene into 2-Pentene ii) 1,2-Dibromopropane into 2-Heptyne iii)1l-Buten-3-yne into Neopentene iv)

Ethyne into Divinylacetylene

Q. What is STEREOSPECIFIC synthesis of alkenes? Write at least one example. (2)

Q Differentiate between photochlorination and photobromination in iso-Butane. Write chemical equations

and justify proportions of the products. (2+2)

Q. Explain THREE features of ring strain. (4)

Q. How would you distinguish HYDRATION in Propene and Cyclopropane? Write chemical equations in

support of your answer. (2)

Q What is the relationship between DIHEDRAL ANGLE and ENERGY? Discuss this with special reference

to n-Butane. (3)

Q. Draw the structures of the following compounds in correct asymmetric perspective. (3)

i) S-Methylethylbenzylammon i um chloride ii) R-3 -Cyanocyclopentanone iii) S-3-Methyl-3-methoxy-4-

hexen-2-one

Q. ETHANAL upon treatment with NaCN/HCl yields a pair of stereoisomers. Draw their structures and

indicate R and 'S' configuration in each isomer. (4)

Q Discuss the role of the following inorganic reagents in organic synthesis. Write at least ONE example in

each case with mechanism. (2+2+2+2)

i) PBrj ii) p-Toluenesulphonylchloride iii) NaBH4 iv) Peracetic acid

Q. Write a more convincing evidence that INVERSION takes place in SN2 reaction. (2)

Q SN and Elimination reactions compete with each other. Under which conditions, elimination reactions are

favorable? Explain with chemical reaction mechanism.

Q. Hydrolysis of methyl chloride is catalysed by the addition of Nal. Explain. 2

Q Give the mechanism of the following conversion. . 2+2+2+1

i) Benzene into p-ter-Butylphenol (ii) Phenol into o-Bromophenol (iii) ter-Butanol into ter-Butyl-iso-

propylether(iv) Methylphcnylether into Phenol

Q. Write THREE different method of the preparation of Ethylene Oxide. 3

Q. How would you prepare p-Hydroxybutanal? Write the mechanism. 2

Q. The C-0 bond length in PHENOL is shorter than the normal value.

Q. AMMONIA is a stronger base than Anmn^

Q.Write ONE example in each case and give short reasons):

i) CANONICAL structures of a molecule without a charge are more stable than those with formal charges

Stcric inhibition of resonance in a compound increases the basicity.

iii) ACETOACETIC ESTER produces a reddish-violet color on treatment with neutral Ferric Chloride

solution.

Q Write all possible Canonical structures of the following and indicate their increasing order of stability

with short reason(s) in each case. 2+2+2+2 •

I. 2.6-Dimcthylnitrobenzcne

II. Phenolate ion

III. 4-Nitrophenolate

IV. Nitrobenzene

Q. How does solvent effect tfie ENOLIZATION in a compound? Give one example. 2

Q. Draw the structures of the following compounds in correct asymmetric perspectives.

I. R-2-Hydroxypropionicacid

II. S-4-EthyIhept- 1-ene-5-yne

Q.Draw all possible geometrical isomers of 2.4-Heptadienc and indicate cis and trans configuration in each.

4

Q. Write reason(s) briefly. 2+2

I. Cyclopentadiene is an unusually acidic hydrocarbon. ,

II. Methyl group in TOLUENE is o-/p-directing for electrophilic substitution reactions..

Q. How will you convert BENZENE into the following compounds and write mechanism where applicable?

2+2+2

I. 3-Bromonitrobenzene

II. 2-Bromonitrobenzene and 4-Bromonitrobenzene

III. n-Propylbenzenc

Q. Benzene is reduced into 1,4-Dihdrobenzene by Two methods. SHOW WITH CHEMICAL reactions. 4

Q. How will you distinguish METHANAL from ETHANAL? Support your answer with chemical reactions

mechanism. 2

Q.Give Reason (s)

I. The oxygen in phenol and phenolate ion show opposite inductive effect. (1)

II. Methanoate ion (HCOO) is more stable than ethanoatc ion (CH3COO) (1)

III. The dipolemoment of cis-l,2-Dichloroethene is 1.90 D while that of trans-1.2- Dichloroethenc is

zero. (1)

IV. .cis-1,3-cyclohexanedicarboxylic acid is an optically inactive compound. . (1)

V. Maleic acid is a stronger acid than Fumaric acid. (2)

VI. D-Glyceraldehyde upon addition of HON yields a pair of stereo isomers instead of a pure compound.

(2)

VII. t-C4H9CI undergoes hydrolysis at a faster rate through SN1 mechanism. (2)

Q. Propene gives three different products when treated

with Br2 in 0 1120 in (ii) CCl4 in (iii) CH3OH and justify your response with reaction mechanism. (4)

Hydration of propene yields primary alcohol in the presence of and secondary alcohol in cold Coned.

H2S0/H20. Explain with mechanism. (4)

Q. Chlorination of butane in the presence of sunlight yields a mixture of halogenated butane. Why? Also

write reason for the major product with mechanism. (2)

Q. Predict the major product in each reaction! (6)

(i) (CH3)3CCf HjO,25M? (ii) (CH3)3CC111,0,65~?

(iii) CH3CHBrCH3 Nioiin.o ?

jocr

(iv) CH<-C-QCiH< cH.MgWmobt ?

11,0' ■

Q. Grignard reagent reacts easily with water, methanol and methylamine. Explain with chemical reactions.

(2)

Q. n-C|8H37Br yields 85% elimination product while n-C|' H370Ts gives 99% substitution product in the

presence of (CH3)COK/(CH3)3COH. Comment on the proportion. (2)

Q. How will you prepare the following compounds starting from benzene using different reagents(s)?

Explain with mechanism. (2+4+4)

I. 4-Nitroacetanilide

II. 2-Hydroxybenzaldehyde

III. Naphthalene

Q. Differentiate the following pair of compounds with appropriate chemical reactions. Give mechanism in

each case. (4)

I. Aniline and Cyclohexylamine

II. Dimethylamine and Trimethylamine

Q. Bring out the following conversions with mechanism: (2+4)

I. Pyridine into 4-Nitropyridine

II. ETHANAL into 2,4,6-Trimethylpyridine.

Q. Synthesize the following compounds from MALONIC ESTER. Write mechanism. (3+3)

I. Cyclobutanecarboxylic acid

II. 3-cyclohexanedicarboxlic acid

Q. Predict the missing products from the following reactions. Support your answer with mechanism. (2+2)

(j) CH,CO,H + SOC1, nCAN9VgCI ?

FcCf, Ether

w RCHjCOjH ,)? .

Q. Naphthalene upon nitration gives one major product while sulphonation in the same compound at two

different temperature yields two isomeric products. Explain with mechanism of each reaction. (4)

Q. Phenanthrene undergoes addition while anthracene substitution reactions. Explain with special reference

to bromihation in each compound. (3)

Q. Explain briefly the drawbacks of Friedel-Crafts reactions in benzene. (3)

Q. Write the order of reactivity of the following compounds in terms of nucleophilic addition reactions. Give

reasons (s). (4)

I1CHO, CH3CHO, CCH3)3CCOC(CH3)3 and

(CH3)2CO *

Q. How will you convert C=0 group of aldehydes and ketones into C=N. Give at least three different

reactions with one mechanism. (4)

Q. Differentiate between acctophenone and benzaldehyde chemically. (2)

Q. Draw all the possible conformers of the following compounds and write the stability order with

reasons(s). (4)

(i) 1,4-Dimethylcyclohexane (ii) n-Butane

Q. How will you resolve dl-pair of 2-hydroxypropionicacid. Explain. (4)

Q. Convert trans-trichlorocrotonic acid into Fumaric acid and /ro/i.v-crotonic acid. (2)

Q. How will you determine the configuration of D-Glucosc. Write stepwise reactions. (7)

Q. Convert P-D-Glucose into stereoisomer" mixture of Methyl <*-D-Glucoside and Methyl P-D-Glucoside.

(3)

Q. Give two methods for the commercial preparation of phenol. 4

Q. What happens when phenol is treated with? 6

(i) Cone. HN03 (ii) CHCIj/aq. (iii) H2CO/NaOH

(iv) Bromine water (v) NaOH/C02 (vi) NaN02/

HC1,0®

* 2.(a) Write down the pme for the following

structures: a (B QJn^M ■■ 5

- oOK

-mOi

Q. Draw the Structure for the following compounds:

(i) Diphenylmethanone (ii) Ethanenitrile (iii) Pyridine (iv) 9,10-Dibromoanthracene (v) Benzenamine

Q. What is hydrogen bonding? Differentiate between intramolecular and intermolecular hydrogen bonding

with examples. 4

Q. Discuss the effects of hydrogen bonding on: 6

Q. Acidic strength (ii) Boiling point (iii) Solubility

Q. Explain why in most of the cases the equatorially bound groups in cyclohexane derivatives are more

stable than axially bound ones. 2

Q. Write down the structure of two lowest molecular weight alkanes that are chiral. 2

Q. A solution of 2.0 g/ml of (+)-2-butanol in 10 cm polarimeter tube has an observed rotation of+27.8~

Calculate the observed rotation if the length of the polarimeter jS decreased to 5 cm.. 2

Q. Assign R and S designation to each of the following molecules: 4

Q. Give the final product(s) in each of thefollowing reactions.

(1) H3C H2 N'

H2Pd(BaS04)

(') H3C

H3C

H3C

aq.KMn04

(v) H3C 0

Q. In the presence of sun lighbeiuenTadds chlorine to form hexachlorohexane but the toluene gives

substitution under the same condition. Account for this. 2

Q. Which of the following groups are ortho and para directing and which are meta directing" 3

-CH3rCN-C0CH3-N02,-Br,-CF3

Q. Explain why? , jq

(a) Hydrolysis of methyl chloride is catalyzed by the addition of sodium iodide. r D

Hydrolysis of tert-butyl chloride is retarded by the addition of sodium chloride.

Optical activity of 2-iodooctajie slowly falls to zero when it is allowed to react with potassium iodide in

acetone.

The rate of formation of tert-butyl ethyl ether from tert-butyl bromide does not increase by changing the

nucleophile from C2H50H to C2H50Na.

Q. How will you synthesize ethyl phenyl ketone from the following substances? The synthesis may not

involve more than two steps. 10

(i) Benzene (ii) Benzaldehyde (iii) Benzoyl chloridd (iv) Benzonitrile (v) Benzoic acid

Q. How would you prepare the following compounds from ethyl acetoacetate? 10

(i) PhCpCH2COCH3 (ii) PhCOCH2CH2COCH3 (iii) 2-Hexanone (iv) cyclopentyl methyl ketone

Q. What do you understand from the following terms?

Exhaustive methylation

Hoffmann degradation

Reductive animation

Q. Write short note on the following:

I. Hantzsch pyridine synthesis

II. Wittig Reaction

III. F.C. Alkylation

Q. Describe the stretching and bending mode of vibrations of an AX system. 5

Q. Show that hybridization of the underlined atoms in the following compounds: 5

(i) CH.= C = CM, (ii) CH,NH,

(iii) 0=£ = 0 (iv> BF,

(v) BF,

(a) Write down the IUPAC Systematic name for the following structures: 2

o <" - O" 1

HO

(iii) (iv) COOl

(b, Write down FOUR synthetic schemes for the synthesis of phenol from benzene. 8

Q. Certain compounds that do not have chiral carbon show optical activity. Give three examples of different

classes of compounds with reasons. 3

quinolineNa

HgS04/feP

Q. An optical active compound with specific rotation of *50" has a small amount of its cnantiomcr as

impuritv and gives an optical rotation of +40" Kind out the percentage of impurity. 3

Q. Write dow n the stereo chemical nomenclature for the following structures:* -1

(P (ii)

(no (iv, cr -■C00"

Br CI I OH

Q. Explain the mechanism. Kinetics and stereochemistry of SNI and SN2 reactions and compare the two

pathways in the reaction:- 6

R X+OII '"n >ROII + X with regard

Relative rates for X = CI. Br. I

Relative rates for R CHj.c?H$ iso-C;H;. Icrt-C.,H.

Efleets on the rates by increasing

<i)|R-X| (ii> [Oilj

Temperature (iv) Proportion of IKO

(d) Possibility of rearrangement.

Explain why? 5x2

o-Nitropheiiol is less acidic than p-Nitrophcnol.

4-Hydroxybenzoic acid is less acidic than 2-llydroxyben/oic acid.

(Hi) Ammonia is stronger base than aniline.

Amino acids are amphoteric.

Pyrrole is a weaker base than pyridine.

Q. Hlow would you synthesize the following compounds starting from ethyl acctoacetate. 3.3.4

CI IA

(i> (ii).

CHy j CM

II

CH,

(iii)

Q. How would you convert D-Glucosc into the following? Show all the steps. '4x2,?

(i) D-Arabinosc (ii) D-Mannosc (iii) D-FructOse (iy) D-Erythrose

Q. What is reductive amination? How is tins useful for the preparation of primary, secondary and tertary

amines? ' 4

Q. Write short notes on:

I. Hofmann degradation of amides.

II. Gabriel synthesis of amines.

Q. How would you prepare the following compounds starting from ben/aldehyde 5x2

(i) Benzoin (ii) 1-phenylpropeiic Benzyl alcohol (iv) Bcnzil (v) Ethyl Phenyl Ketone

Q. Write short note on the following

I. Wolff Kishner Reduction

II. Erics Rearrangment

III. Geometrical Isomerism

Q. Discu:a the absorption spectra of benzene, What is the slicet of (i) chromopliorc and (ii) auxo chromic

groups attached to benzene'* . 5.5

Q. Differentiate b'tw:en met mdtecukr and intermolecular hydrogen bonding g'vjug two example; with

sTuctinc; jj each.

'Nov. \ you synthesize the following centpounds starting from propyne 10

{:) 2-bromcpropane (ii. Propana! (iii) Trans 2-hcxcnc ' av) n-propylbronide (v) Acetone (v ) i -Butyric

3 How will you convert: 10

(p An. line into p-Nitio aniline

Toluene into n.-Nitro ben/ocacid

(iii; lirotno benzene into n-Buty benzene ( v> n-Heptane into Toluene

(v) Acetone into isoprops benzene

Q. Write down structural formulae of the following compounds: 5,5

(i) Allylchloride (ii) methylcyclohexane (iii) Acetanilide (iv)Triphenylmcthanol (v) Phenylacctaldehyde

b) Differentiate clearly between constitutional isomerism

and stereoisomerism with examples.

Q. How will you convert l-chloropropane into: 10

(i) i-iodojSropane (ii)Propenc (iii) 2-Chloropropane (iv) Propyne (v) Propane (vi) n-1lexane

Describe a simple chemical test to distinguish between: 10

(i) FTthanol and methanol (ii) Ethanol and phenol

Uthanol and methanol

Mthahol arid isopropyl alcohol

isopropyl alcohol and tertiary butyl alcohol llow will you prepare:" 10

Formaldehyde from calcium formate

Acetaldehyde from calcium formate

Acetone from culcium acetate

Benzaldehyde from Toluene

Acetaldehyde from Acetyl chloride

Acetaldehyde from Acetylene

Acetone from propyne

Q. Write all steps in the conversion of acetic acid into: 10

(i) Acetamide (ii) Acetyl chloride (iii) Ethane

(iv) Methyl amine (v) Ketone (vi) a-Bromoacetic acid

Q. How can ethyl3mine be prepared from: 6.4

(i) Acetaldehyde (ii) Methyl chloride

(iii) Acetyl chloride

Q. How can Nitrous acid be used to distinguish between primary, secondary and tertiary amines?

Q. What are polysaccharides? Discuss the sources, structure and characteristics of: 10

i) Starch ii) Glycogen iii) Cellulose

Q. What are -Elimination Reaction? Discuss their mechanisms. 5,5

Q. Briefly describe the effect of substrate, base leaving group, solvent and temperature on Elimination

Reactions.

Q. Write the IUPAC systematic name for the following compounds and also draw their structures

(i) Acetonitrilc (ii) Formic Acid (iii) Acetophcnone (iv) Isobutanc (v) Urea5;5

Q. An atomic orbital can be characterized by certain "Quantum numbers". Discuss the importance of these

numbers.

How will you carry out the following conversions? Accounts for your answers. 4.3.3

. CH, CH,

(1) CHj-C-CH =CH, o*CH,-C-CH2CH,OH

CH. l CM,

CH, CH.,

CH,-C-CH=CH2->CH,-C-CH-CH,

CH, . CHjOII

CH, CH,

ia , , CH,-C-CH=CH _*CH ,-C-CH -CH,

la J i i i

CH, OH CH,

Write short notes on the following reactions: 3.4.3

(i) Reformat Sky Reaction (ii) A Idol Condensation

Wolff-Kishner Reduction

a) What is Racemate? How can it be separated into its components?

b) Label the following structures as R or S

HC CjN

(i) r-cooH (ii, Cr.

CI || Q.NP C-CH

,3cooh

rJ-CUUn (iW

as 01011 HO C||.CH(CH.)

Discuss the following syntheses:

Paal-Knorr synthesis of pyrrole

Hantzsch synthesis of pyridine

How would you synthesize benzoic acid from each of the following: 10

(i) Toluene (ii) Acctophenone (iii) Benzonitrile (iv) Benzyl alcohol (v) Styrene

a) Differentiate between intermolecular and intermolecular hydrogen bonding by giving examples with

structure in each case. 4.6

b) Describe the effects of hydrogen bonding on boiling points, solubility, acidity and tautomeric equilibria of

organic molecules. Explain with examples.

Explain why:

The WURTZ reaction is not suitable for tertiary alkyl halide.

It is difficult to prepare the cycloalkanes containing larger than seven-membered ring by using WURTZ

reaction.

Dehalogenation of 1.3-dichloropropane by Zinc in alcohol to give cyclopropane is catalyzed by sodium

iodide.

Chlorination of methyl cyclopeniane yields a complex mixture but its bromination yields one greatly

predominant product.

The heat of combustion of cyclopropane is much higher than that of propane.

How will you synthesize each of the following compounds starting from acctvlenc? 10

(i) Acet.ildehydo (ii) 2-pentync (iii) Glyoxal (iv) Vinyl acetylenc (v) l.l-Dibromocthane

Luckily Dr. Fu yao agree for acceptance letter. He advise me to apply. Please guide me.

CH.CH;GH.