C. S. (MAIN) EXAM 2009

CHEMISTRY

Paper II

Time Allowed Three Hours Maxinuan Marks 300

INSTRUCTIONS

Each question is printed both in Hindi and
in English.

Answers must be written in the medium specified in the Admission Certificate issued to you. which must he stated clearly on the cover of rite anslver-book in the J7Jace provided for the purpose. No marks will be given for the ans,vers i·vritten in a 1ne<liun1 other than that specified in the Acbnission Certificate.

Candidates should attempt Question Nos. 1 and 5 which are conipulsory, and any three of the remaining questions selecting at least one question from each Section.

Assume suitable data if considered necessary and indicate the same clearly.

The number of marks carried by each question is indicated at the end of the question.

Symbols and notations carry usual meaning, unless othenvise indicated.

Section

1. Answer any three of the following
What are the products from ozonolysis of ortho-xylene after treatment with Zn 20
What kind of substitution on benzene ring stabilizes the phenyl carbanion and where is it most effective Explain mechanistically.
Which has higher dipole moment between <img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-1b2.jpg"> and <img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-1b3.jpg"> why? 15+5
Pyridine follows nucleophilic substitution easily but not electrophilic. Explain mechanistically. 20

What are the catalyst(s) for the following chemical reactions?
Aldol condensation
Claisen condensation
Perkin reaction
Fries rearrangement
Pinacol-pinacolone rearrangement 20

2. Fusion of <img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-2a.jpg"> with NaNH2 gives two derivatives p). Explain mechanistically. 15

Optically active <img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-2b.jpg"> refluxing in polar solvent like THF or DMFrecemizes but it does not occur in cyclohexane. Explain. 15
For conversion of C6H6 to C6D6 using excess DCt the used catalyst is one of the following. Identify it and justify with mechanism H2S04 Pd Pt Ni. 15
The addition of Br2 to CH2 CH2 in presence of excess c1- produces Br CH2 CH2- Cl as one of the products. Explain mechanistically.15

3. ldetitify the intermediates and products 1n the following reactions

<img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-3a.jpg"> 4x3=12
<img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-3b.jpg"> 3x3=9
<img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-3c.jpg">
<img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-3d.jpg">
<img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-3e.jpg">
<img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-3f.jpg">

4. Explain the following transformation through mechanism. <img src="E:sirishaCIVILS MAINS 2013CIVILS MAINS-20092009 mains optionals_sireeshaimages14-4a.jpg"> Camphene Chloride 20

Identify the products in following reactions
<img src='./qimages/14-4b.jpg'>

Section

5. Answer any three of the following :4x4=16

Nylon 6 can be produced from a monomer. What is that monomer and what is the mechanism of pol ymerization? Phenol condenses with formaldehyde in acidic medium. What 1s the mechanism of condensation? 20
The presence of P 1 peak parent peak) in mass spectra of organic compounds may be attributable to natural abundance of some isotopes. What are those isotopes Write numbers of major peaks in 1 H NMR spectra of the following compounds: <img src='./qimages/14-5b.jpg'>
Proton NMR of Cl -CH2 CH2Cl shows only one signal whereas Cl CH2- CH Br shows more than one signal. Explain. p-hydroxy acetophenone is mixed with D20 (very exces · in mild alkaline condi tion. The mass spectra of final product (parent peak) will differ from parent peak of p-hydroxy acetop henone. What is the difference in unit of mass 10+10-20
DNA precipitates with cationic polymer but not with anionic poly mer. Explain. Acid hydrolysis of Nylon 6 is faster than acid hydrolysis of polyester. Explain with mechanism. 10+10=20

6. Write prod ucts for photochemical dissociation of 2-pentanone. Write the possible intermediate. <img src='./qimages/14-6a.jpg'>
ion shifts n 1e· transition of C O to higher energy. Explain. 1 2 Which reagent can be used to convert C H3 C H C H CH2 C0 2Me to CH3- CH CH CH2 CH20H. 6
Polar solvent shifts lm of tr re* transi-tion of O to higher value. Explain.12 Ethene and Ethyne unlike propene and propyne do not give C to C multiple bond stretching bonds in their IR spectrum. Explain. 10

7. Write equation for the formation of glyptal resin How can it be made softer 20
Write monomer of Teflon. How is the monomer synthesized l0
In 1 H NMR spectra C2H2 and CF3COOH gives signals at different positions, why 10
Why does produce colour when dissolved in any polar solvent 10
Write suitable reagents for converting cyc.lohexene to OHC(CH2)4CHO. 10

8. When does p-cresol not produce thermosetting polymer with <img src='./qimages/14-8a.jpg'>
What is the name of the reaction <img src='./qimages/14-8b.jpg'>
What are the structural differences between Nylon 6·6 and Nylon 6 10
How are the following compounds distinguished by mass spectrometry DCH2CH2COCH3 CH3CH2CO??D CH3CHDCOCH3 1 5 Write the reactions which produce vinyl chloride from ethanol (in three steps). i5

Note English version of the Instructions is printed on the front cover. of this question paper.