Electrochemical Reduction of 2,2′,6,6′-Tetrabromobisphenol A at Silver Cathodes in Dimethylformamide

2,2′,6,6′-Tetrabromobisphenol A (TBBPA) is a brominated flame retardant that is bonded chemically to epoxy resins in circuit boards and that is added to high-impact polystyrenes.  TBBPA is found ubiquitously throughout the environment in sewage runoffs and in water and soil samples, as well as in living organisms.  There have been many documented methods for the degradation of TBBPA, including both chemical and physical methods.  In this study we have focused on the electrochemical degradation of TBBPA at silver electrodes in dimethylformamide (DMF) containing 0.10 M tetramethylammonium tetrafluoroborate (TMABF₄).  Initially, cyclic voltammograms were recorded to characterize the electrochemical behavior of TBBPA at both glassy carbon and silver cathodes, as shown in the accompanying figure.  At glassy carbon, only two irreversible cathodic peaks are observed.  On the other hand, reduction of TBBPA at a silver cathode gives rise to three cathodic peaks, which appear at potentials significantly more positive than for glassy carbon.  To investigate the possible debromination of TBBPA, controlled-potential (bulk) electrolyses have been performed with a silver gauze electrode in a DMF–0.10 M TMABF₄.  Using GC–MS for the separation, identification, and quantitation of products arising from bulk electrolyses, we have determined that mixtures of mono-, di-, and tribrominated species are produced.