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 0f the following
(20 x
"Which of the following compounds are aromatic? Give reasons to justify your answer: <img src='./qimages/1149-1a1.jpg'>
On the basis 0f modern concept 0f aromaticity how will you explain azulene as blue and shows dipole, moment 0f 0.8 D whereas its isomer naphthalene is colourless and has no dipole moment?
Provide mechanism for the fo11owing reaction
<img src='./qimages/1149-1b.jpg'>
suggest a method for the synthesis of the following compunds using the given reaction. <img src='./qimages/1149-1c.jpg'>
rationalise the products formed in the following reactions.
<img src='./qimages/1149-1d.jpg'>
how would you explain the addition of h1 to tiglic acid and angelic acid(b) to give stereo specifically the erythr0-and threo-beta-iodo acids(c) and (d)respectively insted of a mixture of the acids(c and in each case.
<img src='./qimages/1149-2a.jpg'>
Predict the fonnation of major and ffimor products 1n the followmg reactions and also mdicale the name through which they are asso C1 aled Show the mecharusm of theu fonnati on(20) <img src='./qimages/1149-2b.jpg'>
"A 2pies 2pieS cyc1oaddition reaction is thermally forbidden while it is photochemica11y allowed". Explain by writing the symmetry correlation diagram Give the structure of the product(s) in the following reactions showing mechanism. <img src='./qimages/1149-2c2.jpg'>
3.(a)With suitable mechanism explain how optically active cis-Z-acetoxycyclohexyl tosylate on heating with acetic acid and K-acetate gives the optically active transdiacetate with a slow rate whereas its optically active trans iSomer furnishes the optically inactive trans­diacetate
<img src='./qimages/1149-3a.jpg'>

The optically active Ketone undergoes recemisation 0n treatment with NaOEt as well as dil.H2S04.
<img src='./qimages/1149-3b.jpg'>
Explain the observation with mechanism.(20)
In the reaction shown below with
<img src='./qimages/1149-3c1.jpg'>
the product isolated is and not Explain the reason with mechanism.
Give the name and stereochemistry of the product in the following transformation from A B.
<img src='./qimages/1149-3c2.jpg'>(20)
4. The threo -3-phenyl-2 -butylamine(A) undergoes deamination with nitrous acid in aceticacid and gave the fo11owing results:
<img src='./qimages/1149-4a.jpg
Suggest the possib1e mechanism for the conversion of 6-dimethy1 phenyl allyl either to 4-a11yl-2, 6-dimethy1 phenol How will you prove that it passes through a dienone intermediate?
<img src='./qimages/1149-4b.jpg'>
The transfonnation of hydrazob enzene to benzidine in the presence 0f acids is considered to bean intennolecular rearrangement.
<img src='./qimages/1149-4c.jpg'>
How will you verify it by cross-over experiment?

SECTION B
5. Answer any THREE 0fthe following: (20 x
Give the reaction and show the structure of the polymer pro ducts formed from the following monomers: (ch3)2sicl2 and ch3sicl3 What will be the geometry of these polymers? How are these polymers used?
Predict the pro duct(s) in the reactions given be10w with mechanism wherever possible. <img src='./qimages/1149-5b.jpg'>
Write the structure of the product(s) in the following reactions with mechanism: src='./qimages/1149-5c1.jpg'> src='./qimages/1149-5c2.jpg'>
Deduce the structure 0f the comp ound from the following spectral data assigning reason for each peak:
IR(cm-1 2875, 1720,1622,1310,725
IH NMR 1.23 3 4.25 7.2 5
Mass (rrJz) 138, 96, 91,65,43
Molecular formula: C9Hl0o2.
What are phosphazene polymers? How a pho sphazene polymer having -Q-CH2-CF3 group is prepared? "What are its important surgical uses?
Calculate the lamdamax for the foll0wing using Wood ward-Fi eser ru1e: Account for the changes in the carbonyl stretching frequency in the following.
How will you account for the following mass spectral peaks in C6Hs-CH2-OH? (rrJz) 108, 107, 106, 105, 91,79. Show the fragmentation pattern. The rotational spectrum 0f HCI molecu1e shows that the rotation allines are equally separated by 2070 cm-l Calculate the internuclear bond length. =6.63 xl 0-34 Js, Na =6.023 x 1023).
7. 100Og. of a polymer 0f molecular weight 1000 mole was mixed with 1000 g of another polymer 0f molecular weight 106 g/mo 1e. Calcu1ate the ratio of the weight average molecular weight to number average molecular weight ofthe mixed polymer
Suggest suitab1e reagents for the synthesis 0f the following <img src='./qimages/1149-7b.jpg'>
(i).name the various types of ultramarines.give their composition and uses. (ii)rationalise the following transformations. <img src='./qimages/1149-7c.jpg'>

8.a (i)Free radical polymensation of 3-buladlene gives a polymer Containing-CH2­ and CH=CH-CH2-and ch2-ch-axide -ch=ch2 Proportion of which depends on temperature How will you account for this observation? "Natural rubber is elastic whereas gutta percha is higy crystalline and rigid though both are fanned from the same monomer" Give reasons
How will you explain the fonnation of m/z 149 in the mass spectrum of diethylphthate? Show the fragmentation pattern to show it Suggest reaclanl, reagent and mecharusm for the syntheSis of B from A