Organic 122-final 2005
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(B. Sc. Biochemistry) Second Semester 2005 Subject: Chem 122 (Organic Chemistry)
Full Marks: 100 Pass Marks: 45 Time: 3 hours
Candidates are required to give their answers in their own words as far as practicable. The figure in the margin indicates full marks. 1. 2. 3. 4.
Group (A) Long Questions (Any three) (3× ×14 = 42) Define aromaticity. Explain Huckel's rule and orbital picture of benzene as well as the stability of the benzene ring. Discuss the mechanism of Grignard addition reaction and its synthetic uses for making various types of compounds. Also mention the limitation of Grignard synthesis. Explain acidity of α-hydrogen in carbonyl organic compounds. Discuss fully the mechanism of base promoted as well as acid catalysed halogenations of ketones. a. How can you show that each class of amine yields a different kind of product in its reaction with nitrous acid. b. Write the mechanism of Fries rearrangement.
Group (B) Short Questions: (Any six) (6× ×7 = 42) 1. Explain the structure and acidity of alkynes. 2. Explain the mechanism of nitration and sulphonation in benzene ring. 3. Explain the properties of salts of carboxylic acids in identification and separation of organic acids from other compound 4. Discuss the mechanism of cannizzaro reaction. 5. Discuss alkylation of carbonyl compound via enamines. 6. Discuss the Witting reaction. 7. Outline the synthesis of 1,2,3 – Tribromobenzene from p-Nitroaniline. 8. “Phenol is less stable than phenoxide ion.” Explain. Group (C) Very Short Questions: (Any eight) 1. What happens when acetylene is passed into dil. H2SO4 solution containing HgSO4. 2. Give a list of meta-directing groups. 3. Name a substituent in benzene ring which is deactivator but o-p-directing. 4. What is the characteristic test for –CO-CH3 group in a compound? 5. State the reagent for directly converting acids to alcohols. 6. State the use of thionylchloride. 7. How do you obtain CH3 CH = CH – CHO from CH3 – CHO. 8. What happens when CH3 – COCH2 – COOH is heated? 9. Name a reaction related to aldol condensation. 10. Outline the synthesis of picric acid from chloro – 2,4 – dinitrobenzene. 11. Define sandmeyer reaction. 12. Write the structure formula for: (i) 2,6 – Dibromo – 4 – nitro aniline (ii) Cyclohexylamine (iii)Anisole (iv) Salicylaldehyde ***
(2× ×8 = 16)
Full Marks: 100 Pass Marks: 45 Time: 3 hours
Candidates are required to give their answers in their own words as far as practicable. The figure in the margin indicates full marks. 1. 2. 3. 4.
Group (A) Long Questions (Any three) (3× ×14 = 42) Define aromaticity. Explain Huckel's rule and orbital picture of benzene as well as the stability of the benzene ring. Discuss the mechanism of Grignard addition reaction and its synthetic uses for making various types of compounds. Also mention the limitation of Grignard synthesis. Explain acidity of α-hydrogen in carbonyl organic compounds. Discuss fully the mechanism of base promoted as well as acid catalysed halogenations of ketones. a. How can you show that each class of amine yields a different kind of product in its reaction with nitrous acid. b. Write the mechanism of Fries rearrangement.
Group (B) Short Questions: (Any six) (6× ×7 = 42) 1. Explain the structure and acidity of alkynes. 2. Explain the mechanism of nitration and sulphonation in benzene ring. 3. Explain the properties of salts of carboxylic acids in identification and separation of organic acids from other compound 4. Discuss the mechanism of cannizzaro reaction. 5. Discuss alkylation of carbonyl compound via enamines. 6. Discuss the Witting reaction. 7. Outline the synthesis of 1,2,3 – Tribromobenzene from p-Nitroaniline. 8. “Phenol is less stable than phenoxide ion.” Explain. Group (C) Very Short Questions: (Any eight) 1. What happens when acetylene is passed into dil. H2SO4 solution containing HgSO4. 2. Give a list of meta-directing groups. 3. Name a substituent in benzene ring which is deactivator but o-p-directing. 4. What is the characteristic test for –CO-CH3 group in a compound? 5. State the reagent for directly converting acids to alcohols. 6. State the use of thionylchloride. 7. How do you obtain CH3 CH = CH – CHO from CH3 – CHO. 8. What happens when CH3 – COCH2 – COOH is heated? 9. Name a reaction related to aldol condensation. 10. Outline the synthesis of picric acid from chloro – 2,4 – dinitrobenzene. 11. Define sandmeyer reaction. 12. Write the structure formula for: (i) 2,6 – Dibromo – 4 – nitro aniline (ii) Cyclohexylamine (iii)Anisole (iv) Salicylaldehyde ***
(2× ×8 = 16)
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