The mechanism of the Cannizzaro reaction of Formaldehyde

Abstract

For a wide range of concentrations of formaldehyde and alkali, the Cannizzaro reaction of formaldehyde can be described as the sum of a third and a fourth order reaction. However, the concentrations which are used for the rate equations must be corrected for the amount of methylene glycol anion present. The dissociation constant of methylene glycol as determined from the kinetic data is the same magnitude as that derived electrometrically. The mechanism of the reaction is interpreted as a reaction between formaldehyde and the hydride ion donors CH₂(O^-)(OH) and CH₂(O^-)(O^-) It is shown why the third order reaction proposed by previous workers is not always applicable.