Question Paper CHE2102 Mid Semester Examination 8 January 2021.pdf

The Maharaja Sayajirao University of Baroda M.Sc. Part-I, Mid Semester Examination Paper –II CHE – 2102 [Organic Chemistry] Date : 08.01.2021 (Friday) Time: 11.00 a.m. – 12.00 noon. Q.1 A An...

The Maharaja Sayajirao University of Baroda M.Sc. Part-I, Mid Semester Examination Paper –II CHE – 2102 [Organic Chemistry] Date : 08.01.2021 (Friday) Time: 11.00 a.m. – 12.00 noon. Q.1 A Answer in brief. 04 1 What is Walden Inversion? 2 Show with energy profile diagram (i) Effect of leaving group on SN2 reaction (ii) Effect of solvent on SN2 reaction 3 For conversion of Benzylbromide into benzyltriphenylphosphoniumbromide requires 24 hours reflux in Xylene with triphenylphosphene, but if catalytic amount of LiI is added, the reaction occurs within two hours. Explain Why? 4 What is proof for SN1 mechanism? B Complete the following reactions with mechanism. Mention type/ name of 06 reaction (ANY THREE). 1 70% aq. acetone Cl NaN3 ? H3C 2 H O + (CH3)2NH ? H 3 NaSCH3 CH2Br CH3CN ? 4 Br CH3COONa CH3COOH/H2O ? Q-2 A) Select the most appropriate option to fill in the blank. i) The leaving group in a reaction giving the reactive species with a carbon, deficient of an electron pair is called _____________. (nucleofuge, electrofuge, electrophile, radical) ii) A reaction is favourable with the value of ∆G0 = _________. ( +ve, -ve, either +ve or -ve, zero) iii) An energy profile diagram with reaction involving intermediates has _____ transition state. (no, one, more than one, can’t be predicted) iv) __________ is the thermodynamically most favourable factor. (gain in enthalpy, gain of aromaticity, gain of entropy, gain in free energy) B) Answer the following to the point: i) Draw a labelled energy profile diagram for a diffusion-controlled reaction. ii) Give four points differentiating intermediate and transition state. iii) Give an example in which intermediate can be isolated for the confirmation of its existence with the relevant equation(s). Q-3 A. Why nucleophilic molecular rearrangements are most common? B. What major product is obtained in the following reactions? (write only structure) i. AlCl3 anisole + CH3CH2CH2Cl ? ii. MeO Ph Ph OMe H2SO4 ? HO OH iii. Me dry HCl ? C. Explain the following reactions with mechanism (Any TWO). C1 HNO2 0-5 oC ? NH2 C2 Et Et HNO2 ? HO NH2 C3 O NaOH ? O END