“Loyola College B.Sc. Chemistry April 2009 Synthetics Organic Chemistry And Spectroscopy Question Paper PDF Download”

    LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

WD 22

B.Sc. DEGREE EXAMINATION – CHEMISTRY

SIXTH SEMESTER – April 2009

       CH 6609 / 6603- SYNTHETICS ORGANIC CHEMISTRY AND SPECTROSCOPY

 

 

 

Date & Time: 25/04/2009 / 9:00 – 12:00     Dept. No.                                                       Max. : 100 Marks

 

 

PART – A

Answer ALL questions:                                                                               (10 x 2 = 20)

  1. What is retrosynthetic analysis in Organic chemistry.
  2. What is disconnection approach.
  3. Write the mechanism of C-alkylation of acetoacetic ester.
  4. Write the product of aldol condensation of Acetaldehyde.
  5. Predict the product of Diel’s – Alder reaction.

(i)                                                                            (ii)

 

 

  1. Write the structure of the product

(i)                                                            (ii)

 

 

  1. Calculate the max value for the following compounds using Woodward Fieser rule?

(i)                                                            (ii)

 

 

  1. Concentrated solution of ethanol and 1, 2- glycol in CCl4 exhibit broad O-H stretch near 3350 cm-1 in their IR spectra. On dilution with CCl4 the spectrum of 1, 2 – glycol does not change but that of ethanol exhibits a sharp band at 3600 cm-1 in addition to the broad band at 3350 cm-1. Explain the observation.
  2. C13 is NMR active while C12 is not explain.
  3. How will you account for the appearance of prominent peaks at m/z 31, 42 and 70 in the mass spectrum of n- pentanol.

PART – B

Answer any EIGHT questions:                                                                   (8 x 5 = 40)

  1. Explain Umpolung synthesis.
  2. What is the difference between conversion and synthesis.
  3. Predict the product of Birch reduction of
  • Benzoic acid (ii) Anisole.
  1. Explain the product and mechanism of hydroboration of propene.
  2. Write the mechanism and stereochemistry of Diel’s Alder reaction of

 

  1. Discuss the method of protecting aldehyde and keto group?
  2. Explain the importance of molecular in peak in mass spectra.
  3. Write note on i) bathochromic shift      ii) coupling constants
  4. How many different set of equivalent protons do each of the following compounds have? How many signals would each compound give in its lH NMR spectram
  5. CH3-CH3 ii) CH3-O-CH3      iii) CH3-CH2–      -CH2-CH3                                iv) CH3 –     -O CH3
  6. Give a brief account on Refrence standards used in ‘H NMR spectral technique.
  7. The IR spectrum of methyl salicylate shows the following peaks at 3300 cm-1 1700 cm-1 3050 cm-1, 1540 cm-1, 1590 cm-1 and 2950 cm-1. Attribute these peaks to the following features of the molecule.
  8. What is meant by shielding and Deshielding of protons in NMR spectoscopy.

PART – C

Answer any FOUR questions:                                                                     (4 x 10 = 40)

  1. What are the application of Electrophilic Synthon and Synthetic equivalent in Retro Synthetic analysis.
  2. i) How does IR spectroscopy useful to distinguish between  a) O-nitro phenol and p-

nitrophenol.

  1. A compound having the molecular formula C10H14 exhibits following HlNMR signals. d28(5H singlet) 0.880 (9 H S). Assign the structural formula of the compound.
  2. i) How are the following groups protected and de protected during the synthesis of organic compound.
  3. –NH2 b) –OH group
  4. An organic compound A (molecular formula C9H10O2) exhibits the following spectral data

IR: 1745 cm-1,             1225 cm-1             749 cm-1               697 cm-1

UV: lmax 268, 264

|HNMR=d1.96(3H, S)              5.00(2H, S)          7.22(5H, S)

  1. i) How will you synthesis i) Acetylacetone               ii) Crotonic acid from ethylacetoacetate.
  • “Diels-Alder reaction is highly stereo specific”. Explain.
  1. Using Umpolung reaction how will you synthesis
  2. C6H5-CH2– -CH3               ii)
  3. Explain any two of the following (5+5)
  4. Clemmenson reduction and its mechanism
  5. Working principle of UV=Visible spectrophotometer with a block diagram.
  6. Oxidation by peracids.

 

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