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

Conversion of CCl2FCCIF2 to CCl2FCF3 is achieved in the temperature range, 593-713 K. under flow conditions by using the catalysts, beta -AlF3 or gamm a -alumina- prefluorinated with CCl2F2 or SF4. Aluminium-based catalysts fa vour the formation of asymmetric isomers in the chlorofluoroethane series, hence CCl3CF3 is also a significant product. More highly chlorinated materi als, containing greater than or equal to4 Cl atoms, and CClF2CF3 are minor products. Product composition data provided evidence for the possible pathw ay CCl2FClF2 - CCl3CF3 --> CCl2FCF3. The isomerisation step is believed to be intramolecular and is facile. The apparent fluorination step is best des cribed as a dismutation. (C) 2001 Elsevier Science B.V. All rights reserved .