Cannizzaro reaction

Schematic of the Cannizzaro reaction. Reagents: aldehyde, base, acid work-up. Product: primary alcohol, carboxylic acid.

The Cannizzaro reaction is a redox reaction in which two molecules of an aldehyde are reacted to produce a primary alcohol and a carboxylic acid using a hydroxide base. The reaction begins with hydroxide attack on the carbonyl carbon followed by deprotonation to give a dianion. This unstable intermediate releases a hydride anion which attacks another molecule of aldehyde. In this process the dianion converts to a carboxylate anion and the aldehyde to an alkoxide. The alkoxide then picks up a proton from water to provide the alcohol final product, while the caboxylate is converted to the carboxylic acid product after acid work-up.[1]


Mechanism of the Cannizzaro reaction. Hydride transfer. The carboxylate is less basic than water, thus can not pick up a proton and requires an acid workup to protonate. The alkoxide is more basic than water so this reaction can proceed.


Cannizzaro, S. Ann. Chem. Pharm. 1853, 88, 129–130.