Benzoin condensation

Benzoin condensation

The self condensation of aromatic aldehydes (with no α-hydrogen ) in presence of cyanide ions as a catalyst to α-hydroxy ketones is called benzoin condensation. 
benzoin condensation

Mechanism 
Cyanide ions attacks the carbonyl group to give (1). Cyanide group with its electron withdrawing nature makes aldehydic hydrogen more acidic. the conversion of (1) to (2) is  favourable because the ion (2) is stabilised by both the benzene ring and the cyanide group.The anion (2) attacks another aldehyde carbonyl to form the link between the two molecules. The deprotonation-protonation steps give the alkoxide ion (3). Finally, cyanide ion departs from (3) to give benzoin.
benzoin condensation

Some Other important Reactions

Cannizzaro Reaction

Clemmensen Reduction

Etard Reactions

 

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