LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 05

SECOND SEMESTER – APRIL 2007

CH 2500 – ORGANIC CHEMISTRY – I

 

 

Date & Time: 20/04/2007 / 1:00 – 4:00        Dept. No.                                                Max. : 100 Marks

 

 

PART – A

 

Answer ALL the questions                                   (10 x 2 = 20)

 

1. Classify the following groups into +I and –I groups: i) CH₃ ii) NH₂ iii) NO₂ iv) Cl
2. Give the differences between mesomeric effect and inductive effect.
3. Define torsional strain and torsional energy.
4. Give the eclipsed and staggered conformations of n-butane.
5. Give the IUPAC names and the structures of the products formed by the reaction of 1-pentyne with one mole of HBr and a peroxide.
6. What is Markownikoff rule? Explain with an example.
7. Why is acetylene acidic?
8. What is Diels-Alder addition reaction?
9. Differentiate between enantiomers and diastereomers.
10. Assign R & S notation to the following compounds:

 

PART – B

Answer any Eight questions                                                        (8 x 5 = 20)

 

11. Distinguish between a) absolute and relative configuration b) meso and racemic forms
12. Draw the Fischer-projection formulae for all the possible stereoisomers of 2,3-dichlorobutane and specify as R or S configurations to the asymmetric carbon.
13. How is 1,3-butadien prepared? Give the reactions of 1,3-butadiene with a) maleic anhydride     b) HBr.
14. Explain the mechanism of halogenation of alkane.
15. How will you prepare the following compounds from acetylene:
16. a) acetaldehyde              b) ethyne         c) vinyl chloride
17. Write short notes on i)Wurtz synthesis ii) Corey House synthesis.
18. How will you prepare the following:
19.             i)  n-propanol from propene    (ii) Glycol from ethylene.

 

18. Explain the mechanism of markownikoff and antimarkownikoff addition of propene.
19. Write short notes on a)hydroboration reaction b) addition polymerization reaction
20. Explain the mode of hybridization of carbon in methane, ethylene and acetylene.
21. Explain cis and trans addition with an example.
22. Write down the structural formulae of the olefin from which the following products are obtained on ozonolysis:
23.                     a) cyclopentanone and acetone   b) ethylmethyl ketone and propanaldehyde

 

PART – C

 

Answer any FOUR questions                                                (4 X 10 = 40)

 

23. a) Explain why aliphatic amines are more basic than aromatic amines.

b)Explain the various factors affecting the stability of primary, secondary,                                                     tertiary and methyl carbonium ions

24. Explain the rate of halogenation of alkanes and the factors affecting the rate of the reaction.
25. Explain the 1,4- and 1,2- addition reactions of butadiene in detail.
26. Give the mechanism of the following reactions: a) dehydration of alcohols b) dehydrohalogenation c) peroxide effect d) alkylation of alkene.
27. Bromination of an organic compound(A) of formula C₆H₁₂ yields C₆H₁₂Br₂. On reduction of the compound gives 2-methylpentane. On oxidation it yields a mixture of acetic acid and isobutyric acids. Assign the structural formula to the organic compound. Express the above reaction by chemical equation and give the IUPAC names of A and other products.
28. a) Discuss the conformational analysis of 1,2-dichloroethane with potential energy diagram. b) Give the E or Z notation to the following compounds:

 

 

 

 

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