MSc Chemistry (Organic and Analytical) SEM III Dec 2018-19 CHEMISTRY ORGANIC CHEMISTRY THEORETICAL ORGANIC CHEMISTRY Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate full marks

1. Q1 (a) Attempt any two of the following: 8 marks
   • (i) the product formed in the following reaction and suggest a plausible
   • (ii) stereochemical evidence for NGP reaction with a suitable example
   • (iii) Explain molecular orbital basis for the a-effect
   • (iv) Predict the product formed in the following reaction and suggest a plausible
   • (b) Attempt any one of the following: 04
   • (i) | Draw the molecular orbitals of 1,3,5-hexatriene and comment upon their Explain any four features of Pericyclic reactions with suitable examples
   • (a) Attempt any two of the following: 08
   • (i) Explain the mechanism of Claisen rearrangement with suitable example
   • (ii) | With the help of FMO approach, show that [4+4] cycloaddition reaction is photochemically allowed reaction
   • (iii) Explain symmetry approach in the ring closer reaction of 1,3 — Butadiene
   • (iv) Discuss the Sigma-tropic rearrangements with respect to [1,3] & [1,5] shift with suitable example
   • (b) Attempt any one of the following: 04
   • (i) the synthesis of Vit-D from 7-dehydrocholesterol
   • (ii) Complete the following reaction & explain the stereochemistry involved
2. Q3 (a) Attempt any two of the following: 8 marks
   • (i) the conformation and stereochemistry of D-ring in steroids
   • (ii) What is meant by torsional angle of junction? Explain it with respect to decalin. Draw the conformation of cis-decalin exhibiting ring inversion and torsional angle of junction Explain the influence of conformation in the deamination of 2
   • (iv) (M) is oxidized by chromic acid twice fast than cholestan Elucidate this observation by giving chromic acid mechanism
   • (b) Attempt any one of the following: 04
   • (i) Draw the conformers of cyclononane and give the evidences of its most
   • (ii) Reduction of cyclohexanone with is faster as compared to reduction of cyclodecanone. — Explain this observation with suitable diagrams
3. Q4 (a) Attempt any two of the following: Explain the mechanism of photosensitization 8 marks
   • (ii) Explain the following:
   • i) Quantum Yield Give mechanism of the following reaction
   • (iv) Discuss the mechanism and stereochemistry of Paterno-Buchi reaction
   • (b) Attempt any one of the following: 04
   • (i) Explain the following reactions with examples: Explain the two examples of the following reactions with mechanism:
   • ii) 1, 4 addition reaction of arenes
4. Q5 Attempt any four of the following: 12 marks
   • (a) Write the reaction of generation of carbene. Explain the stability of carbene
   • (b) Discuss the role of FMO in reactions involving hard and soft nucleophiles
   • (c) What is Diel’s Alder & Retro Diel’s Alder reaction? Explain both with suitable example of each
   • (d) What are Chelatropic reactions? Explain with suitable example
   • (e) Suggest the symmetry elements and point group present in (R)-1,3
   • (f) Explain the stereochemistry and the formation of major product by Cope elimination of following compound:
   • (g) Complete the following reaction and give its mechanism
   • (h) Complete the following reactions: ii)

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