Tuesday, February 5, 2008

Aldehydes - Ketones Perkin reaction

The Perkin reaction is a type of aldol condensation of aromatic aldehydes and the anhydride of an aliphatic acid in the presence of sodium salt of the same acid, to give on heating an α,β-unsaturated acid.

Reaction mechanism

The carboxylate anion abstracts a proton from the a-carbon of the anhydride to form carbanion I.
This carbanion undergoes nucleophilic addition to carbonyl carbon of the aldehyde.
The anion II so formed takes up a proton to form a hydroxy compound III which first undergoes dehydration as an anhydride before it is hydrolyzed to the α,β-unsaturated acid.

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