Electrochemical dechlorination of chlorobenzene with a mediator on various metal electrodes

Dechlorination of chlorobenzene has been studied in acetonitrile on metal electrodes (Pt, Cd, Sn, In, Pb, Zn, Ag) using naphthalene as a mediator. Voltammograms of the metal electrodes, except Pt, give redox peaks at −2.94 V (Ag∣Ag+) in the solution containing 10 mM of naphthalene. The cathodic peak at −2.94 V is enhanced with an increase of the concentration of chlorobenzene, evidence that chlorobenzene is also reduced at this potential. The current density of the enhanced cathodic peak depends on the metals in the following order: CdSn < InPb < Zn < Ag. Chlorobenzene has been electrolyzed on Zn and Ag and Pt electrodes at −2.94 V (Ag∣Ag+) in 0.1 M tetraethyl ammonium perchlorate (TEAP) + acetonitrile containing 10 mM of chlorobenzene and naphthalene. Main product of the electrolysis is benzene. The partial current density of benzene also depends on the metals as follows: PtZn < Ag.