Kinetic and Mechanistic Investigation of Electrochemical Oxidation of Hydroquinones in the Absence and Presence of 2-acetyl-gamma-butyrolactone

Abstract

Electrochemical oxidation of hydroquinones (1a,b) was studied in the presence of 2-acetyl-gamma-butyrolactone (3) as nucleophile in phosphate buffer solution (pH 7.0 and c = 0.15 mol L−1):ethanol (80: 20), using cyclic voltammetry and controlled potential coulometry. The results indicated that the p-benzoquinone derived from (1a,b) participates in 1,4-Michael addition reaction with 3 via an EC mechanism which produces the relatively new hydroquinone derivatives (5a,b). The electrochemical synthesis of (5a,b) has been successfully performed on carbon rod electrodes in an undivided cell. Furthermore, the observed homogeneous rate constants of the reaction between hydroquinones and 2-acetyl-gamma-butyrolactone were estimated by comparing the experimental cyclic voltammograms curves with those digitally simulated.