Cannizzaro Reaction

The disproportionation of an aldehyde to an equimolar mixture of primary alcohol and carboxylic salt (i.e., with optimal yield of 50%) when treated with concentrated NaOH or other strong bases that is restricted to aldehydes without α‐hydrogens to undergo aldol condensation is generally known as Cannizzaro reaction. The reaction has been found to be first order in base and second order in aldehyde, whereas at higher base concentrations, it is second order in both base and aldehyde. The hydride transfer is found to take place directly between aldehydes without intervention of reaction medium. The reaction in which the oxidant aldehyde differs from the reductant aldehyde is referred to as the cross (or crossed) Cannizzaro reaction, which is quite useful for synthesizing a high yield of alcohol. The aldehydes are arranged in order of diminishing susceptibility to oxidation: m ‐nitrobenzaldehyde, furfural, p ‐bromobenzaldehyde, benzaldehyde, and p ‐anisaldehyde. Besides this the reaction occurs on a solid surface (e.g., MgO and TiO ₂ ) and in gas phase.