M.Sc-M.Sc Chemistry 1st Year Paper - III : ORGANIC CHEMISTRY (Acharya Nagarjuna University - Center for Distance Education, Guntur, Andhra Pradesh-2013)

(DCHE 03) NR M.Sc. (Previous) DEGREE EXAMINATION, MAY - 2013 
First Year 
Chemistry 
Paper - III : ORGANIC CHEMISTRY 

Time : 03 Hours                                                                            Maximum Marks : 80

Part - A (4 × 8 = 32) 

Answer any Four questions 

1) a) What is meant by hyper conjugation? Why is it also termed as no- bond resonance? 
b) Write a note on tautomerism give examples. 
2) Write a note on: 
a) Huckel’s rule. b) Anti-aromaticity. 
3) Explain the following: 
a) Isotopic effects. b) Steric effects. 
4) Write a note on: 
a) Anchimeric assistance. b) SNi reaction. 
5) a) Discuss the general mechanism and draw an energy profile diagram of aromatic 
electrophilic substitution reactions. 
b) Give the mechanism of Sandmayer reaction give examples. 
6) Explain the terms regio and chemo-selectivity give examples. 
7) a) Write the mechanism of Metal hydride reduction of Saturated Carbonyl Compounds 
give examples. 
b) Give the Mechanism Stobbe reaction. 
8) Discuss the mechanism and stereochemical evidence of E2 elimination reaction. Part - B (4 × 12 = 48) 
Answer any Four questions UNIT – I 9) a) i) Explain annulenes and homo aromaticity. 
ii) Explain why aromatic amines are weaker bases than aliphatic amines? 
OR 
b) i) Discuss the factors affecting relative Stability of Conformations. 
ii) Draw Newman projection formulae for the chair and boat form of cyclohexane? 
Which form is more stable and why? UNIT – II 10) a) i) What are Carbonions? Discuss their characteristics, structure and stability? 
ii) Explain kinetic and thermodynamic control reactions give examples. 
OR 
b) Explain the following: 
i) Nucleophilic substitution at an allylic carbon. 
ii) Ambident nucleophiles. 
iii) Non classical Carbocation. 
UNIT – III 11) a) i) Discuss the orientation and reactivity of aromatic electrophilic substitution 
reactions. 
ii) Explain free radical rearrangements give examples. 
OR 
b) Write the mechanism and stereochemical aspects of addition reactions involving 
electrophile, nucleophile and free radical reactions on Carbon-Carbon multiple bonds 
give examples. UNIT – IV 12) a) Explain the following: 
i) Mannich reaction. 
ii) Aldol condensation. 
iii) E1CB reaction. 
OR 
b) i) Discuss various factors which effect the extent of E1 and E2 eliminations. 
ii) Explain hydrolysis of esters and amides give examples. 
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