LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 19

SIXTH SEMESTER – APRIL 2006

                                                        CH 6604 – NATURAL PRODUCTS

(Also equivalent to CHE 604)

 

 

Date & Time : 24-04-2006/9.00-12.00         Dept. No.                                                       Max. : 100 Marks

PART – A

Answer ALL the questions.                                                               (10 X 2 = 20)

1. Explain isoprene rule with respect to geraniol.
2. Draw the structure of piperonylic acid and caffeine.
3. Predict the product for the reaction between anthracene and maleic anhydride.
4. How is the presence of unsaturation tested in alkaloids?
5. How is urea converted into parabanic acid?
6. Give the resonance structure of naphthalene.
7. Apply Huckel’s rule to predict the aromatic character of thiophene and explain.
8. How is 2-aminopyridine obtained from pyridine?
9. What is nicotinic acid? How is it obtained?
10. What are alkaloids? Give an example for pyridine alkaloid.

PART – B

Answer any EIGHT questions only.                                                   (8 X 5 = 40)

11. Explain Hoffmann’s exhaustive methylation of coniine.
12. Naphthalene on sulphonation at 50 ⁰C and at 150 ⁰C yields different products. Explain.
13. What are carcinogens? Explain the carcinogenic activity of polynuclear hydrocarbons.
14. How is anthracene obtained by Haworth’s synthesis?
15. Resonance energy of benzene is 36 kcal mol^-1 while that of naphthalene is 61 kcal mol^-1. Explain.
16. Electrophilic substitution of pyridine yields 3- substituted product. Explain.
17. Explain the synthesis of uric acid.
18. Write note on anthocyanins.
19. How are the following obtained from pyrrole:
20. Pyrrole-2-carboxylic acid. b. 2-Formylpyrrole.
21. How is the presence of two benzene rings established in naphthalene?
22. Account for the products of oxidation of quinoline with acidified potassium permanganate.
23. How are terpenes isolated?

 

PART – B

Answer any FOUR questions only.                                                     (4 X 10 = 40)

23. Establish the structure of uric acid.
24. Elucidate the structure of nicotine.
25. Describe the constitution of citral.
26. a. Discuss the structure of piperic acid.
27. Write a note on flavones.
28. Explain the following:
29. Skraup’s synthesis b. Conversion of thiophene to thiophene-2-carboxylic acid.

 

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