Aromatic aldehyde oxidation by hexacyanoferrate(III) catalyzed by Ru(VI) in alkaline medium

Abstract

In this study, the selective oxidation of aromatic aldehydes has been investigated using Ru(VI) as a catalyst and hexacyanoferrate (III) as a cooxidant in an alkaline medium. The reaction order with respect to the oxidant and the aromatic aldehyde is complex while the reaction order with respect to Ru(VI) is one. The proposed mechanism presents two catalytic cycles for the two active species of the catalyst. In each cycle, Ru(VI) species forms a complex with the anion of hydrated benzaldehyde which decomposes to form benzoic acid. The function of hexacyanoferrate(III) is the regeneration of catalyst species. A quantitative structure–activity relationship was analyzed using the Hammett equation for decomposition complex step. This analysis showed that deactivating groups in para- position enhances this process.