Electrochemical oxidation of catecholamines in the presence of aromatic amines: interplay between inter- and intramolecular nucleophilic addition

摘要

The reactions of electrochemically generated o-quinones from oxidation of catecholamines with aniline derivatives have been studied using cyclic voltammetry. There is a close and pH-dependent interplay between intra and intermolecular Michael addition reactions of side chain amine group of catecholamines and anilines toward the electrochemically generated o-quinone. The pH dependence of reactions has been studied and the condition for domination of each reaction was obtained. The observed homogeneous rate constants of reactions were estimated by digital simulation of cyclic voltammograms for each pathway. The reactivities and the rate constants of Michael addition of anilines depend on the electron-withdrawing character of their substituent, which have been studied quantitatively.