Electrochemical reduction of dichlorodifluoromethane in acetonitrile medium to useful fluorinated compounds

The electrochemical reduction of dichlorodifluoromethane (CFC-12) at Ag, Cu, Au, Pt and Ni electrodes in acetonitrile and 0.1 M (C4H9)(4)NBr as supporting electrolyte has been studied. The main gaseous products were found to be CF2=CF2. CH2F2 and CH3F. Small amounts of CHClF2 and CH4 were also detected. Among the main products. CF2=CF2 and CH2F2 are of great practical importance, because the first is the monomer for the production of Teflon and the second is an excellent candidate for low temperature refrigeration applications, which in addition does not cause depletion of ozone. Silver was found to be the most efficient electrode for the reduction of CFC-12. because the rate of the reduction was greater than at the other metals and the current efficiencies for CF2=CF2 (38%) and CH2F2 (44%) were also high. Among the other electrodes, Pt gave also high current efficiencies but the reduction rate was much lower. The increase of the negative potential at the Ag electrode leads to a significant increase in the rate of the electrochemical reduction. The electroreduction of CFC-12 was also studied in mixed acetonitrile + water solutions. The experimental results indicated an almost linear decrease of the reduction rate with the increase of the water content. This was attributed to the decreased solubility of CFC-12 in water. The formation rate of CF2=CF2 was also significantly decreased. (C) 1999 Elsevier Science S.A. All rights reserved.