Mechanism of the cross Cannizzaro reaction of 2, 4-dimethoxybenzaldehyde with formaldehyde in aqueous KOH solutions
The kinetics of the cross Cannizzaro reaction of 2,4-dimethoxybenzaldehyde (DMBA) with formaldehyde (FA) in aqueous KOH solutions in the range of concentrations 4.89–36.3% was studied spectrophotometrically.
The formation of the reaction products occurs by two parallel pathways through activated complexes of an un-ionized DMBA molecule and a doubly ionized form of FA with the hydroxide cation and without it.
The ratios of the constants characterizing the reactivity of the redox pair DMBA-FA without assistance of the cation and with its assistance, as well as the equilibrium constants of the reactions of formation of the singly ionized form of both aldehydes, were determined.
Electrophilic assistance of the cations of the hydroxide is confirmed by experiments with additions of the salt KCl to aqueous KOH solutions.
KeywordsFormaldehyde Hydroxide Aldehyde Equilibrium Constant DMBA
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