Exam Details
| Subject | organic chemistry — ii | |
| Paper | ||
| Exam / Course | m.sc in chemistry | |
| Department | ||
| Organization | alagappa university | |
| Position | ||
| Exam Date | November, 2017 | |
| City, State | tamil nadu, karaikudi |
Question Paper
M.Sc. DEGREE EXAMINATION, NOVEMBER 2017
Second Semester
Chemistry
ORGANIC CHEMISTRY — II
(CBCS 2014 onwards)
Time 3 Hours Maximum 75 Marks
Part A (10 x 2 20)
Answer all questions.
1. Sodium borohydride is mild reducing agent than lithium
aluminium hydride Comment on it.
2. Write the chemical equation including the structure of
the major product for the following reaction
Ph.CO.CH Ph
H O/HOAC
SeO
3. What are ylides? How ylides are used in Wittig reaction?
4. What is Curtius rearrangement?
5. Define partial rate factor for a given group.
6. Predict the sign of for the ionization of phenol.
Sub. Code
4MCH2C1
AFF-4881
2
wk12
7. Assign the S notation for the following compounds
8. What is Cram's rule?
9. Bring out the differences between configuration and
conformation.
10. Draw and explain the stable conformation of menthyl
chloride.
Part B x 5 25)
Answer all questions, choosing either or
11. Describe the mechanism of Meerwein-Pondorf-
Verley reduction.
Or
Narrate the mechanism of Wolf-Kishner reduction.
12. Write a note on Reformatsky reaction and its
applications.
Or
Discuss the mechanism of Claisen ester
condensation.
AFF-4881
3
wk12
13. Hammett equation is a linear free energy
relationship. Substantiate.
Or
Explain SNAr mechanism with a suitable example.
14. Define the following terms
Prochirality
Enantiotopic ligand
Diastereotopic ligand.
Or
Give an account of asymmetric synthesis.
15. Narrate the conformational analysis of n-butane.
Or
Write briefly on stereochemistry of ansa compounds.
Part C x 10 30)
Answer any three questions.
16. Discuss the synthetic applications of the following
reagents in organic synthesis
Periodic acid
OsO4 .
Write an account on Birch reduction.
17. Discuss the mechanism of (3.5 3.5 3.0)
Sommelet-Hauser rearrangement
Dienone-Phenol rearrangement
Baeyer-Villeger rearrangement.
AFF-4881
4
wk12
18. Write the mechanism for Friedel-Crafts alkylation.
n-propylbenzene cannot be prepared by this
method. Why?
Account for the observation that o-bromoanisole
on treatment with KNH2 in liquid NH3 gives
m-anisidine.
19. Explain the optical activity of biphenyls and
spiranes.
Discuss stereospecific reaction with a suitable
example.
20. Describe the conformations of cis and trans-1,2-
dimethylcyclohexanes, which is more stable? Why?
Write a note on optical activity of these two isomers.
Cis-4-tertiarybutylcyclohexane-1-ol is easily
oxidised by chromic acid compared to trans isomer.
Why?
———————
Second Semester
Chemistry
ORGANIC CHEMISTRY — II
(CBCS 2014 onwards)
Time 3 Hours Maximum 75 Marks
Part A (10 x 2 20)
Answer all questions.
1. Sodium borohydride is mild reducing agent than lithium
aluminium hydride Comment on it.
2. Write the chemical equation including the structure of
the major product for the following reaction
Ph.CO.CH Ph
H O/HOAC
SeO
3. What are ylides? How ylides are used in Wittig reaction?
4. What is Curtius rearrangement?
5. Define partial rate factor for a given group.
6. Predict the sign of for the ionization of phenol.
Sub. Code
4MCH2C1
AFF-4881
2
wk12
7. Assign the S notation for the following compounds
8. What is Cram's rule?
9. Bring out the differences between configuration and
conformation.
10. Draw and explain the stable conformation of menthyl
chloride.
Part B x 5 25)
Answer all questions, choosing either or
11. Describe the mechanism of Meerwein-Pondorf-
Verley reduction.
Or
Narrate the mechanism of Wolf-Kishner reduction.
12. Write a note on Reformatsky reaction and its
applications.
Or
Discuss the mechanism of Claisen ester
condensation.
AFF-4881
3
wk12
13. Hammett equation is a linear free energy
relationship. Substantiate.
Or
Explain SNAr mechanism with a suitable example.
14. Define the following terms
Prochirality
Enantiotopic ligand
Diastereotopic ligand.
Or
Give an account of asymmetric synthesis.
15. Narrate the conformational analysis of n-butane.
Or
Write briefly on stereochemistry of ansa compounds.
Part C x 10 30)
Answer any three questions.
16. Discuss the synthetic applications of the following
reagents in organic synthesis
Periodic acid
OsO4 .
Write an account on Birch reduction.
17. Discuss the mechanism of (3.5 3.5 3.0)
Sommelet-Hauser rearrangement
Dienone-Phenol rearrangement
Baeyer-Villeger rearrangement.
AFF-4881
4
wk12
18. Write the mechanism for Friedel-Crafts alkylation.
n-propylbenzene cannot be prepared by this
method. Why?
Account for the observation that o-bromoanisole
on treatment with KNH2 in liquid NH3 gives
m-anisidine.
19. Explain the optical activity of biphenyls and
spiranes.
Discuss stereospecific reaction with a suitable
example.
20. Describe the conformations of cis and trans-1,2-
dimethylcyclohexanes, which is more stable? Why?
Write a note on optical activity of these two isomers.
Cis-4-tertiarybutylcyclohexane-1-ol is easily
oxidised by chromic acid compared to trans isomer.
Why?
———————
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