Electrocatalytic Reduction of 1,1,2-Trichloro-1,2,2-trifluoroethane (CFC-113) at Silver Cathodes in Organic and Organic–Aqueous Solvents

Abstract

Cyclic voltammetry and controlled-potential (bulk) electrolysis have been utilized to probe the electrocatalytic activity of silver cathodes for the reduction of CFC-113 in acetonitrile, dimethylformamide, and propylene carbonate as well as 50:50 mixtures of these solvents with water, each system containing 0.050 M tetramethylammonium tetrafluoroborate. Cyclic voltammograms for reduction of CFC-113 at silver show two irreversible cathodic peaks attributable to stepwise production of 1-chloro-1,2,2-trifluoroethene (CFC-1113) and 1,2,2-trifluoroethene (HFC-1123). In organic–aqueous solvents, these two cathodic peaks appear at significantly less negative potentials than those seen with pure organic solvents. Electrolyses of CFC-113 in aprotic media at a silver gauze electrode held at potentials corresponding to each of the observed cathodic peaks afford CFC-1113 (85–91% yield) in a two-electron process and HFC-1123 (82–93% yield) in an overall four-electron process, respectively. Upon addition of water to DMF and ACN, CFC-1113 is formed in essentially quantitative yield for electrolyses at potentials corresponding to the first cathodic peak; at potentials corresponding to the second cathodic peak, CFC-1113 (27–29%) and HFC-1123 (64–72%) are major products.