Electrochemical Oxidation of Catechols in the Presence of Dimethyl Phosphite

The reaction of electrochemically generated o-benzoquinones from the oxidation of catechol derivatives as Michael acceptors with dimethyl phosphite as nucleophile has been studied using cyclic voltammetry. The reaction mechanism is believed to be EC comprising oxidation of catechol moiety of these antioxidants followed by Michael addition of dimethyl phosphite. The observed homogeneous rate constants (k_obs) for the reactions were estimated by comparing the experimental voltammetric responses with the digitally simulated results based on the proposed mechanism. In addition, the effects of nucleophile concentration and of substitutent group of the catechols on the voltammetric behaviour and the rate constants of the chemical reactions are described.