Kinetics Study of Electrochemically Induced Michael Reaction of Benzoquinones with Triphenylphosphine

The electrochemical oxidation of 3,4-dihydroxybenzaldehyde (1), 3,4-dihydroxybenzoic acid (2) and 2,5-dihydroxybenzoic acid (3) were studied in the presence of triphenylphosphine (4) as a nucleophile using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinones derived from oxidation of 3,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid participate in Michael addition reaction with triphenylphosphine (4). In this work, based on an EC mechanism, the observed homogeneous rate constants (kobs) of the reaction of produced benzoquinones with triphenylphosphine (4) were estimated by comparing the experimental cyclic voltammograms with the digitally simulated results