Cannizzaro Reaction

The disproportionation (self redox) of aldehydes lacking 

α-hydrogen atoms in presence of strong base to form salt of an acid and a primary alcohol is known as Cannizzaro reaction. The cannizzaro reaction is an example of a general class of reactions known as disproportionation reactions.

Although the cannizzaro reaction is characteristic od aldehydes lacking 

α-hydrogens, a few aldehydes having α-hydrogens are known which undergo Cannizzaro's reaction.

Cannizzaro Reaction Mechanism

Step 1: Attack of Nucleophile.

Step 2: Formation of Dianion by Deprotonation 

Step 3: Transfer of Hydride ion

Step 4: Salt and the alcohol is formed