Specific features of electrochemical reduction of α,α,α′,α′-tetrabromo-p-xylene at its low concentrations

Abstract

In the cyclic voltamograms for electrochemical reduction of α,α,α′,α′-tetrabromo-p-xylene at its concentrations of 5 and 10 mM in dimethylformamide solution of 0.1 M Bu₄NBF₄, taken at glassy-carbon electrode, four current peaks corresponding to consecutive stages of the reduction process are observed for the first time. The many times repeated potential cycling from 0 V (SCE) to the value approaching the 2nd peak potential results in the electrode passivation; a film of the intermediate product of the α,α,α′,α′-tetrabromo-p-xylene reduction is deposited at the electrode, whose composition may be-(BrCH-C₆H₄-CHBr-BrCH-C₆H₄-CHBr)_n-. When the electrode covered with the deposited film is transferred to a solution of the same composition, in which the primary cycling was performed, yet free from α,α,α′,α′-tetrabromo-p-xylene, and underwent to potential cycling up to −2V, the first cycle demonstrates a current peak that is due to the film reduction. A redox-active poly(p-phenylenevinylene) forms at the electrode.