Oxidation of phosphorous acid and ethyl phosphonates by permanganate

Abstract

The kinetics of the permanganate oxidation of P(III) compounds (phosphorous acid, mono- and diethyl phosphonate and their anions) have been investigated at pH 0–8.3 and pH>12. Results indicate that attack of the oxidant on the PH bond is rate-determining for all substrates in both acidic and basic solutions. Deprotonation of the PH bond prior to oxidation does not take place with the exception of diethyl phosphonate at pH>7, where the reaction proceeds via two parallel pathways. Although the products of the reaction do vary with pH, they can all be derived from the same Mn(V) intermediate. There is evidence to suggest that mixed anhydride formation of the type Mn VOP III may play an essential role in the formation of the final products.