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

摘要

Conversion of CCl_2FCCIF_2 to CCI_2FCF_3 is achieved in the temperature range,593-713 K, under flow conditions by using the atalysts, #beta#-AIF_3 or #gamma#-alumina,prefluorinated with CCI_2F_2 or SF_4. Aluminium-based catalysts favour the formation of asymmetric isomers in the chlorofluoroethane series, hence CCI_3CF_3 is also a sinificant product. More highly chlorinated materials, containing>=4 CI atms, and CCIF_2CF_3 are minor products. Product composition data provided evidence for hte possible pathway CCI_2FCIF_2->CCI_3CF_3->CCI_2FCF_3. The isomerisation step is believed to be intramolecular and is facile. The apparent fluorination step is best described as a dismutation.