Cannizzaro Reaction: Mechanism | Examples

Cannizzaro Reaction is a base-catalyzed redox reaction in which aromatic aldehydes, formaldehyde, or other aliphatic aldehydes lacking α-hydrogen are converted into the corresponding alcohols and carboxylic acids. Cannizzaro reaction is a named reaction in organic chemistry. Here, we will explore the Cannizzaro Reaction and its mechanism, accompanied by some interesting examples.

Cannizzaro Reaction Mechanism:

Several mechanisms have been proposed; the hydride transfer mechanism is most widely accepted.

1. OH⁻ attacks the carbonyl carbon of the aldehyde.
2. The adduct is deprotonated under basic conditions to form a dianion.
3. The dianion enables hydride (H⁻) transfer from the aldehydic carbon.
4. The hydride attacks another aldehyde molecule (rate-determining step), forming an alkoxide.
5. The alkoxide is protonated by water to give a primary alcohol.

Cannizzaro Reaction Examples:

Here are a few synthetic applications of the Cannizzaro reaction in organic chemistry.

References :

1. Mechanism of the Cannizzaro reaction
2. Cannizzaro Reaction