Redox reactions between molecular oxygen and tetrachlorohydroquinone at the water∣1,2-dichloroethane interface

Abstract

The redox process between molecular oxygen, O2, in an aqueous solution, W, and tetrachlorohydroquinone, CQH2, in 1,2-dichloroethane, DCE, at the W ∣ DCE interface was investigated by electrolyses at different potential differences applied between the two phases, Eappl. Three different overall redox reactions were found to occur depending on Eappl. After electrolysis, the final reduction products of O2 in W were H2O as well as a small amount of H2O2 and the final oxidation products of CQH2 in DCE were the tetrachloroquinone anion radical, CQ−, for one range of Eappl, H2O as well as H2O2 and tetrachloroquinone, CQ, for a second range, and H2O2 and CQ for a third range. The redox processes were elucidated taking into account the results obtained by polarography for charge transfer at the W ∣ DCE interface in addition to the results mentioned above. It was also demonstrated that redox reactions between O2 and CQH2 could be realised and controlled, not only by the electrolysis, but also by ion transfer reactions at the interface coupled with the redox reactions.