Electrochemical behavior of p-benzoquinone, 2,3,5,6-tetrachloroquinone and 1,4-naphthoquinone in chloroform—I. In the absence of proton donors

Abstract

The electrochemical behavior of p-benzoquinone ( I), 2,3,5,6-tetrachloroquinone ( II) and 1,4-naphthoquinone ( III) has been studied in chloroform using TBAPC 0.50 M as supporting electrolyte. In the absence of proton donors, all of these compounds exhibit two one-electron reversible waves due to a reversible charge transfer without a coupled chemical reaction. The cathodically generated semiquinone of I and III can easily react with the constituents of solutions and be converted to a non-electroreducible species, whereas the semiquinone of II is stable. The dianion formed from the reduction of I at hmde can participate in a fast chemical electron transfer reaction with the reduction product of the solvent and be converted to free radical again. Such a phenomena has been observed for III only in low scan rates, but never for II.