LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – CHEMISTRY
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)
- What are protecting groups? Give an example of a protecting group for amines and alcohols.
- What is raney nickel and Adam’s catalyst?
- Distinguish between linear and convergent method of synthesis.
- Predict the product and reason for the formation of the product.
- Add the necessary reagents for the forward and reverse reactions.
- Identify the base peak when acetone undergoes fragmentation during mass spectral study.
- Define hyperchromic shift. How does it arise in the electronic spectrum of an organic compound?
- Name the methods by which non-first order NMR spectrum is resolved into a first order spectrum.
- Calculate the frequency regions for N=O stretching vibrations.
- Define the following a) auxochromes b) shielding effect
PART – B
Answer any eight questions (8 × 5 = 40 marks)
- How are the following conversions effected?
- Predict which of the following products would be got in Baeyer-Villiger oxidation of cyclohexylmethyl ketone.Why?
- Give the reterosynthesis and the synthesis of 2-aminocyclohexanone using umpolung concepts.
- Give the reterosynthesis and the synthesis of the following.
- Explain a) Aldol condensation b) Michael addition reaction
- What are the diene and the dienophile used in the synthesis of the following compounds?
- What is solvent cut-off region? How do solvents affect the lmax of any compound? Explain with suitable examples.
- Write the various fragmentation pattern for an arbitrary compound A–B-C–D.
- What are the advantages of FT-IR over dispersive IR spectrophotometer? Give suitable evidences to mark the differences.
- Assign the IR spectral regions and calculate lmax of the following compound
- What are the factors that affect the coupling constants of NMR signals? Explain any three in detail.
- Explain the following with respect to 13C-NMR spectroscopy
- a) Deuterium coupling b) nuclear overhauser effect
PART – C
Answer any four questions (4 × 10 = 40 marks)
- Predict the product with mechanism
- Give the reterosynthesis and the synthesis of the following
- a) Predict the product with mechanism for the reaction of EAA with traces of
sodium hydrogen carbonate.
b) How are the following conversions effected?
- a) Predict the number of NMR signals with increasing order of d values for each of the following compounds.
- i) phenylacetic acid
- ii) o-hydroxyacetophenone
- b) Of the given pairs of isomers which will show the longest wavelength of UV absorption. Give reasons.
- i) 1,2-pentadiene and 1,3-pentadiene
- ii) 4-hept-1-enone and 4-hept-2-enone
- For the given compound predict the following
- a) IR vibrational frequencies for various groups present
- b) Mass spectral fragmentation pattern
- c) Proton NMR spectral data with splitting and chemical shift values.
- Elucidate the structure of the given organic compound from the following spectral data (Annexure-I). The molecular formula of the compound is C6H10O2