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Question : 1
Total: 4
SECTION - A
Explain the following reactions:
(a) Clemmensen reaction
(b) Stephen reaction
Solution:
(a) Clemmensen's reduction: This reaction is used to reduce carbonyl compounds to form simple hydrocarbons in presence of zinc amalgam and concentrated hydrochloric acid.
(b) Stephen Reaction: This reaction is used to synthesize aldehydes from nitriles or cyanides. Firstly, nitriles or cyanides are reduced in the presence of stannous chloride and hydrochloric acid in ethyl acetate solvent to form imine intermediate. Then hydrolysis of this intermediate with water gives corresponding aldehyde.
CH 3 − C ≡ N + 2 [ H ]
CH 3 − CH
= NH + HCl
+ NH 4 Cl
(b) Stephen Reaction: This reaction is used to synthesize aldehydes from nitriles or cyanides. Firstly, nitriles or cyanides are reduced in the presence of stannous chloride and hydrochloric acid in ethyl acetate solvent to form imine intermediate. Then hydrolysis of this intermediate with water gives corresponding aldehyde.
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