LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – CHEMISTRY
THIRD SEMESTER – APRIL 2008
CH 3502 – ORGANIC FUNCTIONAL GROUPS – I
Date : 26/04/2008 Dept. No. Max. : 100 Marks
Time : 1:00 – 4:00
PART – A
(10 x 2 = 20 marks)
Answer ALL the questions.
- Explain why 10 alkyl halides undergo nucleophitic substitution only by SN2.
- Name the products obtained in the addition of HBr to propere in the absence and presence of peroxide.
- What happens when acetophenone is treated with I2 / NaOH?
- Why p-nitrophenol has higher boiling point than o-nitrophenol?
- What are mixed ethers? Give examples.
- How is anisole prepared? What happens when anisole is treated with excess of HI?
- Name the products obtained form 2-hexanone in Norrish type II reaction.
- What is Cannizzaro’s reaction?
- Compare and account for the acidity of acetic acid, prop ionic acid and chloroacetic acid.
- What is the action of heat on malonic and succinic acids?
PART – B
(8 x 5 = 40 marks)
Answer any EIGHT questions.
- Give any two methods of preparation of chlorobenzene. Starting from chlorobenzene how are the following compounds prepared?
- a) o-dichlorobenzene b) aniline c) DDT
- Discuss the effect of nature of substrate, nucleophile and solvent in nucleophilic substitution.
- a) Account for the acidity of phenol
- b) How would you prepare the following compounds from phenol?
- i) o – Cresol ii) Benzene iii) Phenyl acetate.
- Explain the nitration of Phenol with Mechanism.
- How are alcohols prepared by hydroboration method? Give the mechanism of the reaction.
- a) Why are ethers less reactive than epoxides?
- b) How is ethylene oxide prepared? How does it react with methanol and ammonia?
- a) Write the IUPAC names of ethyl methyl ether and anisole.
- b) Give any two methods of preparation of diethyl ether. Mention a reaction where ether behaves as a Lewis base.
- What is Reformatsky reaction? How is it useful in organic synthesis?
- Discuss Norrish type I reaction.
- Give the products of the following reactions.
- Benzaldehyde +
- Acetaldehyde + Malonic ester
- Acetone +
- Acetaldehyde +Malonic ester
- a) What is meant by transesterification?
- b) Discuss the action of heat on and – amino acids.
- Give any two methods of preparation of adipic acid. Write its IUPAC name. How would you convert adipic acid into cyclopentanone and NYLON-6,6?
PART – C
(4 x 10 = 40 marks)
Answer any FOUR questions.
- Explain E1 mechanism of dehydrohalogenation of alkyl halides. Discuss the orientation and reactivity of alkyl halides in dehydrohalogenation.
- a) Identify the products in the following sequence of reactions
Isopropyl alcohol ABC D
- b) Discuss the following reactions of phenol
- i) Coupling reaction ii) Reimer – Tiemann reaction
- a) Explain Williamson’s synthesis of ethers with mechanism.
- b) Discuss the cleavage of ethers with HI
- Discuss the following reactions with mechanism
- a) Wittig reaction b) Benzoin condensation
- a) How do you convert benzaldehyde into cinnamaldehyde? Explain with mechanism.
- b) Arrange the following compounds in the increasing order of acidity. Give reason. Benzoic acid, p-toluic acid, p-nitrobenzoic acid and p-chlorobenzoic acid.
- a) How is acetyl chloride prepared from acetic acid? How are the following compounds prepared from acetyl chloride?
- Acetaldehyde ii) Acetophenone iii) Acetone
- b) Give the mechanism of esterification.
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