Kinetics and mechanism of the oxidation of methanol by aquomanganese(III) ions in aqueous perchlorate media
Abstract
The rate of oxidation of methanol by MnIII ions in aqueous perchlorate media is first order in both [MnIII]Total and [CH3OH]Total, and the observed second-order rate constant varies with both [HClO4] and [Mn2+]. As MnIII–methanol complexes have been detected spectrophotometrically, it is suggested that the oxidation is an inner-sphere reaction with [Mn3+CH3OHaq] and [Mn3+CH3O–aq][Mn3+aq] and [MnOH2+aq]. Various mechanisms to account for the retarding influence of Mn2+ ions and the effect of H+ ions are tested experimentally, and it is concluded that the Mn2+ ion, the ·CH2OH radical and H+aq ion are formed initially in a solvent cage with the rate of the back reaction increased by additional Mn2+ ions present in the wall of the solvent cage.