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CHEMISTRY

I Time Allowed Three Hours I

Maximum Marks 200 I


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QUESTION PAPER SPECIFIC INSTRUCTIONS

Please read each of the following instructions carefully
before attempting questions

There are EIGHT questions in all, out of which FIVE are to be attempted.


Question Nos. 1 and 5 are compulsory. Out of the remaining SIX questions, THREE are to
be attempted selecting at least ONE question from each of the two Sections A and B.
Attempts of questions shall be counted in chronological order. Unless struck off, attempt


of a question shall be counted even if attempted partly. Any page or portion of the page


left blank in the Question-cum-Answer Booklet must be clearly struck off.
All questions carry equal marks. The number of marks carried by a question/part is
indicated against it.


Answers must be written in ENGLISH only.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Assume suitable data, if necessary and indicate the same clearly.
Neat sketches may be drawn, wherever required.



1 [P.T.O.




SECTION-A

1. Answer briefly the folloWing
Indicate the type o.. bonding in ferrocene while commenting on its aromatic character.
Dipole moments of pyrrole and furan are in opposite direction. Explain.
(c)Predict the site of protonation for each of the following molecules PhCH CH3CONH2, Pyrrole, 2-AminopyridineI

(d)Explain the basis of your answer. Explain which of the following reactions would be faster

<img images/1310-1d.jpg'>
The nitrile, can be hydrolysed ve,y readily to corresponding <img images/1310-1e.jpg'> amide, which is extremely difliC)Uit to hydrolyse further. Discuss.
Explain why reacts faster than when treated with aqueous silver nitrate
<img images/1310-1f.jpg'>

(g)The rate of solvolysis of benzyl bromide in aqueous media is decreased in the presence of lithiub bromide but not in the presence of lithium nitrate. However, none of ihese salts affects the rate of solvolysis of methyl bromide. Explain.

Explain why ethyl formate condenses with 2-methyl cyclohexanone in the presence of a base to yield and not
<img images/1310-1h.jpg'>
2. Azulene has a dipole moment despite the fact that there is no functional group attached to it. Explain.
<img images/1310-2a.jpg'>

If aldol condensation of acetone in the presence of D20 is stopped before Offercompletion, the unreacted acetone is found to be deuterated. an explanation for this observa:-ion. 10

Kinetic observations on the following reaction give the rate constant k to be proportional to concentration of acetaldehyde and also to the concentration of hydroxide ion. How is this information helpful in deducing a possible reaction mechanism for it?
2ch3cho->oh-ch3ch9oh)ch2cho
explain formation of the major product in the thermal decomposition of the tetra-alkyl ammonium salt
<img images/1310-2d.jpg'>
3. Which of the following I or would undergo Claisen rearrangement faster? Give reasons in support of your answer 10
<img images/1310-3a.jpg'>
Explain why iodine is often used as a catalyst in aromaticbromination reactions.

Discuss the mechanism of the reaction of N-bromosuccinimide with toluene. 10
(c)Complete the following sigm.atropic reactions <img images/1310-3c.jpg'>

Apply Woodward-Hoffmann rules to predict the reaction between ethene
and allyl cation.
(ii)fllowing reaction and give mechanism for it

<img images/1310-3d2.jpg'>

Outline the steps in the following transformation with corresponding structures <img images/1310-4a.jpg'>

Give the products µi the reaction of CH2-N N+with ethyl methyl ketone. 10
8-Quinolinol yield, 5 and 7 substituted isomers on Reimer-Tiemann reaction. Explain the reaction mechanism. 10
Complete the follqwing reaction with structures and products 10
SECTION-B
5. Answer the following
Sx8=40
Give the major product of the reaction
<img images/1310-5a.jpg'>
and possible mechanism involved.

Predict the order of rates of SN 1 and SN 2 reactions in the following solvents with dielectric constants given in the parentheses
C2H50H CH30H Hexane Water Benzene (2·3)

The reaction between an alcohol and SOC12 to give alkyl chloride is accompanied by inversion of configuration when pyridine is used as the solvent. In the absence of pyridine, the same reaction leads_ to retention of configuration. Explain.
Explain why the presence of cesium(III) or Zn(II} modifies the stereochemistry of borohydride reduction of cyclohex-2-enone.
How will you obtain the following in the laboratory?
<img images/1310-4d2.jpg'>
The rotational spectrum of CO shows a series of lines placed 3·84235 cm-1 apart. Calculate the moment of inertia of C 0 bond. 6 ·626 x 10-27 erg-sec}
(f)Explain the ESR spectrum of isopropyl alcohol radical.
Given green, blue and yellow dyes. Which dye absorbs the shortest wavelength and which the longest?
(ii)List all the electronic transitions possible for CC1 4 CH2 cyclopentane and CH30H. Illustrate McLafferty rearrangement with a suitable example .
Give the significance of two types of molecular weights in polymers. 10
(b)How do secondary and tertiary structures of proteins differ from each other in terms of nature of bonding and interactions? What happens in quaternary structures? 10

What is cross-linking in the context of polymers? Give one method for obtaining polyvinyl alcohol. 10
Give the major product of the following reactions 10
<img images/1310-6d.jpg'>

Complete the following r..actions giving their mechanism Sx4=20
<img images/1310-7a.jpg'>
Predict the products of the following reactions. Justify
Sx2=10

(c)Identify the products A and B in the given transformations, and explain the difference 5x2= 10

8. Explain why a polar solvent usually shifts the 7t transition to longer wavelength and n transition to shorter wavelength. How many fundamental vibrational frequencies would you expect to observe in the IR spectrum of CO 2 Discuss. 10
Assign the molecular structures for C 5H8 and C 6H2 when both give only one singlet in their 1 H-NMR spectra. Predict the molecular ion peak which occurs at m z 76 in the mass spectrum of phthalic anhydride. 10
An organic compound gave the following spectral data
Mass 73, 91, 149, 164 IR v 1730 cm-1
1 H-NMR delta 2·0 ppm delta: 2·93 ppm t 7 Hz))delta: 4·30 ppm t 7 delta: 7·3 ppm Deduce the structure of the compound.