LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

DB 21

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FIRST SEMESTER – November 2008

           CH 1806 – ORGANIC REACTION MECHANISM & STEREOCHEMISTRY

 

 

 

Date : 04-11-08                 Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

Part-A

                                                     Answer ALL questions.                                      (10 ´ 2 = 20)

1. R-CN is prepared by treating RCOO^– with BrCN. Where the carbon in RCN comes from? How?
2. How would you effect the following conversion? Explain with mechanism.
3. What is memory effect in rearrangement? Explain with an example.
4. What happens when phenyl azide is heated with aniline? Explain the formation of the product.
5. Explain the mechanism of ozonolysis of alkenes with an example.
6. What would be the preferred conformer of trans-1,2-dibromocyclohexane? And how its conformation changes with solvent polarity?
7. Explain why the optically active 2-benzoylpropionic acid undergoes racemization when treated with sodium ethoxide in ethanol?
8. Define enantiomeric excess. What is its percentage value for active and racemic products?
9. Solvolysis rate of cis-4-t-butyl cyclohexyl tosylate is greater than that of trans-isomer. Explain.
10. What is atrolactic acid rule? Give one example.

 

Part-B

                                                     Answer any eight questions.                              (8 ´ 5 = 40)

11. Explain the mechanism of Arndt-Eistert synthesis. Mention any one evidence for the mechanism.
12. How do isotopic labeling and stereochemistry help in predicting suitable reaction mechanisms? Give examples.
13. Explain kinetic and thermodynamic controls of a chemical reaction with a suitable examples.
14. ‘Diazotisation of aniline follows II order kinetics in nitrous acid’. Explain the mechanism.
15. How was the mechanism of von-Ritcher rearrangement confirmed? Explain the steps.
16. How would you effect ring cyclisation reaction in Fischer-Indole synthesis? Explain with mechanism.
17. What are the conditions to be fulfilled for a resolution process through diastereomers formation?
18. Why the deamination of (Ph)(Ph’)(OH)C-CH(NH₂)CH₃ does not follow Curtin-Hammet principle? Explain.
19. Discuss the steric course of the acetolysis reaction of 2-phenyl-3-pentyl tosylate &
    3-phenyl-2-pentyl tosylate.
20. Predict the stereochemical change of acetolysis of 3-methoxy-2-bromobutane in the presence of silver acetate in acetic acid.
21. Discuss the conformation analysis of 1,2 & 1,3-disubstituted cyclohexane.
22. Predict the Cotton effect for the following compounds
23. a)                                      b)                                      c)

 

 

Part-C

                                                     Answer any four  questions.                              (4 ´ 10 = 40)

23. a) How does the kinetic study in chain and parallel reactions help to design the reaction mechanism? Explain with suitable examples.
24. b) Explain the mechanism of Favorskii rearrangement. How is it useful in ring contraction reactions?
25. a) Explain the Wagner Meerwein rearrangement reactions. How does neighbouring group help in this rearrangement? How do elimination and substitution reactions compete in the product formation?
26. b) Explain the mechanism of the following rearrangement reactions. (2 ´ 2½)
27. a) Beckman rearrangement        b) Baeyer Villiger rearrangement
28. a) How do amines undergo dehydrogenation? Explain the mechanism.
29. b) Explain Gomberg-Bachmann Pinacol synthesis with a suitable example.
30. c) Explain the mechanism of cannizaro reaction.
31. a) Discuss the optical isomerism of allenes and spiranes.
32. b) Explain the reaction of erythro-3-bromo-2-butanol with HBr
33. Explain the following with example
34. a) Cram’s cyclic model
35. b) Atropisomerism
36. c) Chemical method of racemisation by anion intermediate formation
37. Discuss in detail the stereo selective synthesis of yohimbine.

 

Go To Main Page

         LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

WD 49

FOURTH SEMESTER – April 2009

CH 4955 – ORGANIC CHEMICAL TECHNOLOGY

 

 

 

Date & Time: 28/04/2009 / 9:00 – 12:00  Dept. No.                                                 Max. : 100 Marks

 

 

PART-A

Answer ALL questions.                                                                       (10 ´ 2 = 20 marks)

 

1. Define back mixing. What are its advantages and disadvantages?
2. Why sulphonated products are very much useful industrially? Give reasons with example.
3. What are the types of hydrogenating agents?
4. Compare batch and parallel reactors.
5. Narrate the preparation of titanium dioxide.
6. A simple U-tube manometer is filled with mercury (specific gravity = 13.6) and the liquid above the mercury level is carbon tetrachloride (specific gravity = 1.6). The manometer reads 8.30 in. What is the pressure difference over the manometer in inches of water?
7. What is Reynolds number? Give its significances.
8. What is velocity gradient in a laminar flow?
9. Define Couette flow.
10. What is theoretical or equilibrium diagram?

 

 

PART-B

Answer any EIGHT questions.                                                           (8 ´ 5 = 40 marks)

 

11. What are the physical factors that affect chemical process kinetics of chemical reactions? Write a short note on each.
12. How is nitration of 2-methylpentane carried out? What are the products formed? Write the mechanism of the reaction.
13. Explain in detail the workup procedure for sulphonation reaction and its products.
14. How are various types of chlorination reactions performed industrially?
15. What is the need for a research and development unit in industry? Discuss in detail.
16. With the flow diagram explain the manufacture of paint.
17. Describe the pump work in Bernoulli equation.

 

18. Write short notes on impellers.
19. Explain the working principle of bubble cap column with diagram.

 

 

 

20. Explain the following
21. a) energy balance over a flow system
22. b) effect of temperature upon heat of the reaction
23. Describe the various components involved in the fractionating column.
24. What is differential distillation and give its applications?

 

PART-C

Answer any FOUR questions.                                                            (4 ´ 10 = 40 marks)

 

23. a) Explain the effect of back-mixing on the product distribution and holding time in parallel and series reactions.
24. b) How are temperature controlled reactions performed industrially?
25. c) How is spent acid from nitration reaction recycled?
26. a) Explain the method of nitration of hydrocarbons using Schmid nitrator.
27. b) How is phenol manufactured industrially from cumene? Explain in detail.
28. a) Explain the industrial preparation of hydrogenation of vegetable oil.
29. b) What are the functions of quality control unit?
30. a) Derive Barometric equation.
31. b) Give the working principle of continuous gravity decanter.
32. a) Explain the terms Newtonian and non-Newtonian flow.
33. b) Write note on the mechanical energy balance in potential flow.
34. How will you calculate the vapour composition of a mixture using Raoult’s law?

 

Go To Main page