Dehalogenation of Chlorinated Phenols during Oxidative Coupling

Dehalogenation of chlorophenols by oxidoreductive enzymes is well-documented, but the cause of this phenomenon has not yet been determined. In this study, release of chloride ions was observed during two oxidative coupling processes, polymerization of chlorinated phenols and their binding to humic acid. The reactions were catalyzed by two oxidoreductases and an inorganic catalyst (birnessite). The dehalogenation patterns indicated that release of chloride ions is caused by the free-radical reaction of oxidative coupling and takes place when the unpaired electron of a free radical is located at a chlorine-substituted aromatic carbon. These findings have helped to elucidate various aspects of oxidative coupling during polymerization and binding processes.