Cannizzaro Reaction

This redox disproportionation of non-enolizable aldehydes to carboxylic acids and alcohols is conducted in concentrated base.
α-Keto aldehydes give the product of an intramolecular disproportionation in excellent yields.

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Mechanism of the Cannizzaro Reaction

An interesting variant, the Crossed Cannizzaro Reaction, uses formaldehyde as reducing agent:

At the present time, various oxidizing and reducing agents can be used to carry out such conversions (with higher yields), so that today the Cannizzaro Reaction has limited synthetic utility except for the abovementioned conversion of α-keto aldehydes.
The Cannizzaro Reaction should be kept in mind as a source of potential side products when aldehydes are treated under basic conditions