Conversion of 1,1,2-trichlorotrifluoroethane to 1,1,1-trichlorotrifluoroethane and 1,1-dichlorotetrafluoroethane over aluminium-based catalysts

Conversion of CCl2FCClF2 to CCl2FCF3 is achieved in the temperature range, 593–713 K, under flow conditions by using the catalysts, β-AlF3 or γ-alumina, prefluorinated with CCl2F2 or SF4. Aluminium-based catalysts favour the formation of asymmetric isomers in the chlorofluoroethane series, hence CCl3CF3 is also a significant product. More highly chlorinated materials, containing ≥4 Cl atoms, and CClF2CF3 are minor products. Product composition data provided evidence for the possible pathway CCl2FClF2→CCl3CF3→CCl2FCF3. The isomerisation step is believed to be intramolecular and is facile. The apparent fluorination step is best described as a dismutation.