National Institute of Technology 2006 B.E Chemical Engineering Mid - Sem, or, Elective: Organic Chemistry - Question Paper

t NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA, SURATHKAL, SRINIVASNAGAR -
575 025 DK Department of Chemistry
III SEM. B. TECH. (CH) (CY-205, 3-0-0)
Time: 90 minutes. Max. marks: 40
Note: ans all ques.. every ques. carries eight marks.
1. (a) discuss (i) Knoevenagel's reactions of ethyl cyanoacetate and (ii) keto-enol tautomerism
in ethyl acetoacetate. (4 marks)
(b). What do you mean by asymmetric synthesis ? discuss the rules governed in specifying R and S configurations to enantiomers with suitable examples. (4 marks)
2. (a) How is acetoacetic ester prepared in the laboratory ? Write the mechanism of. the
reaction. What is ketonic hydrolysis ? (4 marks)
(b) provide reasons for the following:
(i) The hydrogens on the methylene carbon are acidic in ethyl nitro acetate.
(ii) The boiling point of keto form of ethyl acetaoacetate is higher than that of enol
form.
(iii)The conformation in which methyl group occupying equatorial position is preferred in the structure of methyl cyclohexane. (4 marks)

3. (a) How are the subsequent compounds prepared from diethyl malonate ?
(i) 2-Methylbutanoic acid (ii) Hexanedioic acid. (3 marks)
(b) Explain Reformatsky reaction with a suitable example. provide its mechanism. (3 marks)
(c) Classify the subsequent compounds as aromatic and nonaromatics. Justify your ans.
(2 marks)
(i) Cyclo octatetraene ' ' (ii) pyrrole
(iii) cycloheptatrienyl cation. (iv) cyclopentadienyl cation.
4. (a) Write an account of (i) electrophilic additions (ii) nucleophilic addition reactions across
carbon-carbon double bonds in acrolein. provide examples. (4 marks)
(b) Give any 2 distinguishing properties of maleic acid and fumaric acid. (2 marks)
(c) What are ketenes ? How is aceto acetic ester found from it? (2 marks)
5. (a) How is butyl lithium prepared ? Write its reaction with (i) acetaldehyde (ii) carbon
dioxide (iii) pyridine. (4 marks)
(b) How do you prepare (i) tetraethyl lead (ii) tetraethyl silane (iii) ethane and
(iv) propanoic acid from ethyl magnesium iodide ? (4 marks)
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Earning:   Approval pending.