A Kinetic Study of the Oxidations of Dihydroxo(dioxalato)chromate(III) and Dihydroxo(dimalonato)chromate(III) by Hydrogen Peroxide in Aqueous Ammonia

Abstract

The main reaction scheme of the H₂O₂ oxidations of dihydroxo(dioxalato)chromate(III)and dihydroxo(dimalonato)chromate(III) in basic media is presumed as follows. Like the oxidations of [Cr(edta)(OH)]^2- and [Cr(hedta)(OH)]^-, the primary reaction forms hydrogenperoxochromium(III), which is oxidized immediately by the coordinated O₂H^- to a Crv intermediate. The formation of the Cr^v intermediate is confirmed by ESR and visible spectroscopy. It is likely that the Crv intermediate is further oxidized to CrO₄^2- by H₂O₂.