Time Allowed: 3 hours Maximum Marks: 300
Candi dates should attempt Question Nos. 1 and 5 which are compulsory, and any three 0 f the remaining questions selecting at least one question from each Section. Assume suitable data if considered necessary and indicate the same clearly.

1.Answer any three of the following (20x 3
(a)Indicate which of the following compounds is aromatic, non-aromatic and anti-aromatic in
character and give explanation for your answer
<img src='./qimages/1094-1a.jpg'>

Explain why 1-hydroxybenzene exists entirely in the enolic form whereas 2­hydroxypyridine exists
very largely in the ketonic form i.e, the lactam form,
Explain the difference between kinetic control and thermodynamic control of a
reaction with the help of a potential energy diagram. 10= 20)
(c)Formulate the following sequence of reactions and give mechanism for the formation of product in each step

<img src='./qimages/1094-1c.jpg'>
What is the role of ethylene glycol in the above sequence of reactions?
suitable reagents,how will you convert toluene into ethyl p-aminobenzoate?

(ii)Give mechanistic explanation for the following observed fact:
CH3CHO 4HCHO C(CH20H)4 HCOOH.

Give explanations for the following observations
the reaction of 3-phenyl-l-propene with HI, the major product formed is l-phenyl­l-iodcpropane.
(ii)Treatment of 0-chlorotoluene with sodamide in liquid ammonia yie1ds a mixture 0f 0­and m-toluidines.
(iii)Pyrrole is a much weaker base compared to pyridine (by several powers of l0). (10x3=30)

(b)Give mechanisms forthe following conversions:
<img src='./qimages/1094-2b.jpg'>
What evidence you can present in support of your mechanism for the above reactions? (10x3=30)

3.Formulate the reactions and give mechanistic explanation for each step of the following:
(a)Treatment of cinnamic acid with bromine in refluxing CCl4 gives dibromocinnamic acid which with excess aq.NaOH gives (in two stages) phenyl propiolic acid.
(b)Reaction of -Butanol with thionyl chloride yields(R)2-chiorobutane which with sodium azide under SN2 conditions gives an azido derivative. The latter on catalytic hydrogenation leads to (S)-2-aminobutane which with excess Mel and subsequent Hofmann elimination gives l-butene.

Nitration of pyrrole with nitronium acetate gives 2-nitropyrrole whereas nitration of indole with the same reagent gives 3-ritroindole Explain.
(ii)Using appropriate reagents, how will you transform thiophene into 5-nitrothi ophene­2-aldehyde? Explain giving the mechanisms.
Heating a mixture of m-chloroaniline with glycerol in the presence of an acid catalyst gives a mixture of someric products i.e., chloroquinolines. What are these products and how are they formed?
(ii)Treatment of phthalic anhydride with urea yields phthalimide which with bromine in aq. NaOH gives anthranilic acid. Explain the reactions giving mechanisms.

SEcnON B

5. answer any THREE 0fthe foll0wing:
Write the structures of all-trans and all-cis po1yisoprene.
Explain the difference between si1icones and silicates.
(iii)Using the technique of mass spectrometry, indicate how will you distinguish between the three identical-mass-compounds (Mol.wt.58)i.e. CH3CH2CH2CH3, CH3N=N-CH3 and CH3CH2-CHO?
In the mass spectrum of acetophenone, a meta-stable peak was observed at 565. Explain what is it due to. x 4 20)
Write the structures of the products formed in the Birch reduction of anisole and benzaldehyde and explain their formation.
(ii)Describe a method for the conversion of 1-methy1-cyc1ohexene to 2­ methylcyclohexanone and explain the mechanism. (10 x 2 20)

the following transitions according to the amount of energy required and give explanation for your grading on the basis of Molecular Orbital Theory in a qualitative manner:­
<img src='./qimages/1094-5c1.jpg'>

The IR spectrum of p-nitrobenzy1 alcohol, when recorded in the KBr phase, shows a
medium, broad absorption at around 3200 cm­l The same absorption shifts to 3450
cm-1 as medium, sharp absorption when recorded in CHCI3 solution. Explain. (10 x 2 20)

Explain why TMS is used as a reference standard in lH NMR spectroscopy.
What is hyperfine splitting in ESR spectroscopy and what is its significance?
Write the structures of the two isomeric alcohols corresponding to a molecu1ar formula of C3H8O and explain their proton NMR spectra.
What is the difference between a "sensitiser" and a quencher" in photochemistry?
Explain your answer with one example for each. x 4 20)
Using FMO approach, give exp1anation for the following reactions:
<img src='./qimages/1094-6a.jpg'>
Write the structure of the product formed by condensation po1ymerisation of terephthaiic acid and ethylenediamine and explain its formation.

(ii)The glass transition temperature of a polymer is O°C. What will be its behaviour (in terms 0f its mechanical properties) at 25°C and at 25°C?

What are the products formed by free-radical poymerisation of di fluoroacetylene?


(c)Explain the following transformations
<img src='./qimages/1094-6c.jpg'>

7.(a)(i)Explain the difference between singlet and triplet states 0f 3-butadiene

(ii)Photolysis of ethyl methyl ketone gives biacetyl and n-butane whereas that of butyrophenone gives acetophenone and ethylene as products Explain (10x2=20)
(b)Predict which of the following pairs of compounds will have higher lamda max values and why?
(i)CH3-CH2-OH and CH3CHO

<img src='./qimages/1094-7b2.jpg'>
(iii)Trans Ph-CH=CH-CH3 and Ph-CH2CH=CH2
Piperidine and <img src='./qimages/1094-7b4.jpg'>
<img src='./qimages/1094-7b5.jpg'>
(c)Using lR spectroscopy, indicate how will you differentiate between the following pairs of compounds?

(i)Benzyl chloride and Benzyl Cyanide
(ii)Aniline and N-methylaniline
(ili)Cyc1ohexanone and Cyclohexanol
(iv)Benzoic acid and Benzaldehyde
(v)Styrene and Phenylacetylene(5x4=20)



8.(a)Indicate how you can Identify the products of the following reaction using 1H NMR spectroscopy?
<img src='./qimages/1094-8a.jpg'>


explain how can you use 1H NMR to Identify the following isomers?
<img src='./qimages/1094-8a.jpg'>

What is meant by rotational degrees of freedom for a molecule? Explain the selection rules for rotational spectra of molecules
(ii)How do you assay bulk drugs using UV-Visible spectroscopy?
(iii)The molecular fonnula of a compound was found to be C3H3Cl5.In its 1H NMR spectrum, it showed Signals at delta 4.52(t) and 6.07(d). The ratio of Integrals was found to be 2 cms:4 cms. What 1s the structure of this compounds?

(iv)The mass spectrum of a compound showed its M at 177 Its IR spectrum showed peaks at 3000 cm (medium, sharp), 2700 cm-1 (medium, sharp), 1660 cm 1(strong, sharp) and no other diagnostic absorptions. Its 1H NMR spectrum showed Signals at delta 1.25 3.4 4H),6.6-7.4 (A2B2 4H) and 9.7 1H) The compound analyzed for C 74.6% H 8.6% and N 8.1%. No eVidence for the presence of S or halogens cound be found. Deduce the structure of this compound.