Electrochemical synthesis of N1,N4-diphenyl-2-(phenylsulfonyl) benzene-1,4-diamine derivatives: Introducing an example of ECDispCMich mechanism

The electrochemical oxidation of N,N'-diphenyl-l,4-phenylenediamine (DPD) has been studied using cyclic voltammetry and controlled potential coulometry methods. The results revealed that DPD shows two one-electron oxidation-reduction peaks. In the first step DPD via a single-electron process is converted to the related radical cation (DPD center dot+) and second step is conversion of DPD center dot+ to N-(4-phenylimino) cyclohexa-2,5-dienylidene) benzenamine (CHD) via a one-electron/two-protons process. Our results also show that DPD center dot+ participates in disproportionation reaction and is converted to DPD and CHD. The rate of this reaction is pH dependent and increases with increasing pH. Furthermore, the electrochemical oxidation of DPD has been studied in the presence of arylsulfinic acids as nucleophiles. The results showed that electrochemically generated CHD participates in Michael addition reaction with arylsulfinic acids via a novel "ECDispCMich" mechanism and is converted to the N-1,N-4-diphenyl-2-phenylsulfonyl) benzene-1,4-diamine derivatives. In this work, a facile and green electrochemical method for the synthesis of some new N-1,N-4-diphenyl-2-(phenylsulfonyl) benzene-1,4-diamine derivatives in good yields using controlled-potential electrolysis at a carbon electrode is also reported. (C) 2015 Elsevier Ltd. All rights reserved.