LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
M.Sc. DEGREE EXAMINATION – CHEMISTRY
SECOND SEMESTER – APRIL 2012
CH 2953 – CHEMISTRY OF HETEROCYCLICS AND NATURAL PRODUCTS
Date : 24-04-2012 Dept. No. Max. : 100 Marks
Time : 9:00 – 12:00
Part-A
Answer ALL questions: (10 ´ 2 = 20 Marks)
- Compare the aromaticity of pyrrole, thiophene and furan.
- How is a carbazole synthesized?
- Mention the pharmacological activities of alkaloids.
- What is Herzig Meyer method of estimation of alkaloids?
- What are tannins? How are they different from flavonoids?
- Define the following
- a) isoprene rule b) gem-dialkyl rule
- How is the presence of C-methyl group determined?
- Give the Ziesel’s method of estimation of –OCH3 groups in anthocyanins.
- How is the position of double bond in zinziberene confirmed?
- Give the mechanism for the following conversion.
Part-B
Answer any EIGHT questions: (8 ´ 5 = 40 Marks)
- Nucleophilic substitution takes place readily on pyridine than benzene. Why?
- Explain the reactivity of quinoline towards electrophilic substitution reaction.
- What is the end product of Hoffmann degradation of N-methylpiperidine?
- How is atropine synthesized?
- Explain the following reactions.
- a) Hoffmann exhaustive methylation reaction
- b) Zerewitinoff reaction
- Explain Baker Venkataraman synthesis of flavonoids.
- Effect the conversion of 2-(1-naphthyl)ethylmagnesium bromide to Diels hydrocarbon.
- Mention the use of the following reagents in the structural characterization of squalene.
- a) Na/amyl alcohol b) Ac2O/1% H2SO4
- Discuss the structural elucidation of cadinene.
- Give the structure of gibberellic acid. How would you prove the presence of
(i) lactone ring and ii) two types of -OH groups in it? - Give the Robinson method of synthesis of hirsutidin chloride.
- Elucidate the structure of pelargolidin chloride
Part-C
Answer any FOUR questions: (4 ´ 10 = 40 Marks)
- a) Explain the electrophilic and nucleophilic substitution reactions in quinoline. (6)
- b) How is thiophene synthesized from furan? (4)
- a) Write the classification of alkaloids with examples. (5)
- b) What are flavonoids? Mention their biological importance. (5)
- Write the complete structural elucidation of Morphine. (10)
- a) Effect the following conversions. (2 × 2.5)
- i) camphoric acid to camphor
- ii) cadinene to 2,7-dimethylcadalene
- b) Identify A-E in the following. (5)
- Discuss the structural elucidation of zinziberene. (10)
- a) Give the synthesis of oestrone from 3-(3-methoxyphenyl)-1-bromopropane. (5)
- b) Discuss the structural elucidation of cyanidin chloride. (5)