Cannizzaro reaction
Abstract
The Cannizzaro reaction is a dismutation of two aldehydes lacking α-hydrogen atoms. In the presence of a strong base and heat, one aldehyde molecule is oxidized to a carboxylic acid while the other is reduced to a primary alcohol. When two different aldehydes are used, a mixture of all possible products are obtained.
Keywords
Aldehyde, Carboxylic acid, Alcohol, Dismutation
Category
Aldehyde/Ketone
Mechanism
First, a hydroxide ion attacks the carbonyl carbon of one aldehyde molecule, forming a tetrahedral alkoxide intermediate. This intermediate then transfers a hydride to the carbonyl carbon of a second aldehyde molecule, simultaneously generating a carboxylate and an alcohol. Upon acidic workup, the carboxylic acid is then obtained.
If one of the reagents is the formaldehyde, the products obtained are formiate and the corresponding alcohol.
Recent review
Chatterjee, B.; Mondal, D.; Bera, S. Synthetic applications of the Cannizzaro reaction. Beilstein J. Org. Chem. 2024, 20, 1376-1395.