LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 18

SIXTH SEMESTER – APRIL 2006

                           CH 6603 – SYNTHETICS ORG.CHEM. & ORG. SPECTROSCOPY

(Also equivalent to CHE 603)

 

 

Date & Time : 26-04-2006/9.00-12.00         Dept. No.                                                       Max. : 100 Marks

 

 

PART – A

                                                Answer all the questions                   (10 ×2 = 20 marks)

1. What are protecting groups? Give an example of a protecting group for amines and alcohols.
2. What is raney nickel and Adam’s catalyst?
3. Distinguish between linear and convergent method of synthesis.
4. Predict the product and reason for the formation of the product.
5. Add the necessary reagents for the forward and reverse reactions.
6. Identify the base peak when acetone undergoes fragmentation during mass spectral study.
7. Define hyperchromic shift. How does it arise in the electronic spectrum of an organic compound?
8. Name the methods by which non-first order NMR spectrum is resolved into a first order spectrum.
9. Calculate the frequency regions for N=O stretching vibrations.
10. Define the following a) auxochromes         b)  shielding effect

 

PART – B

                                                Answer any eight questions            (8 × 5 = 40 marks)

11. How are the following conversions effected?
12. Predict which of the following products would be got in Baeyer-Villiger oxidation of cyclohexylmethyl ketone.Why?

 

13. Give the reterosynthesis and the synthesis of 2-aminocyclohexanone using umpolung concepts.
14. Give the reterosynthesis and the synthesis of the following.
15. Explain a) Aldol condensation b) Michael addition reaction
16. What are the diene and the dienophile used in the synthesis of the following compounds?
17. What is solvent cut-off region? How do solvents affect the lmax of any compound? Explain with suitable examples.
18. Write the various fragmentation pattern for an arbitrary compound A–B-C–D.
19. What are the advantages of FT-IR over dispersive IR spectrophotometer? Give suitable evidences to mark the differences.
20. Assign the IR spectral regions and calculate lmax of the following compound

 

21. What are the factors that affect the coupling constants of NMR signals? Explain any three in detail.
22. Explain the following with respect to ¹³C-NMR spectroscopy
23. a) Deuterium coupling b) nuclear overhauser effect

PART – C

Answer any four questions            (4 × 10 = 40 marks)

23. Predict the product with mechanism
24. Give the reterosynthesis and the synthesis of the following
25. a) Predict the product with mechanism for the reaction of EAA with traces of
    sodium hydrogen carbonate.
    b) How are the following conversions effected?
26. a) Predict the number of NMR signals with increasing order of d values for each of the following compounds.
27. i) phenylacetic acid
28. ii) o-hydroxyacetophenone
29. b) Of the given pairs of isomers which will show the longest wavelength of UV absorption. Give reasons.
30. i) 1,2-pentadiene and 1,3-pentadiene
31. ii) 4-hept-1-enone and 4-hept-2-enone
32. For the given compound predict the following
33. a) IR vibrational frequencies for various groups present
34. b) Mass spectral fragmentation pattern
35. c) Proton NMR spectral data with splitting and chemical shift values.

CH₃-CH(CH₃)-CH₂-COOH

28. Elucidate the structure of the given organic compound from the following spectral data (Annexure-I). The molecular formula of the compound is C₆H₁₀O₂

 

 

 

 

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