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Cannizzaro Reaction

Cannizaro Reaction: Introduction

Reaction principle

The Cannizaro reaction represents the disproportionation of an aldehyde into a carboxylic acid and an alcohol. Alternatively, the reaction can be classified as a redox reaction because one molecule of aldehyde oxidizes another to the acid and is itself reduced to the primary alcohol. More useful is the crossed-Cannizaro reaction in which formaldehyde is reacted with another aldehyde. The formaldehyde reduces the aldehyde to alcohol and is itself oxidized to formic acid.

Fig.1
Disproportionation of benzaldehyde
Fig.2
Crossed-Cannizaro reaction with benzaldehyde

Industrial importance

The combination of aldol condensation and crossed-Cannizaro reaction generates polyols from formaldehyde and other aldehydes. An important use of the reaction is the preparation of Pentaerythrit from acetaldehyde. Polyols are very useful and find many applications in industry.

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