PREPARATION OF PERHALOGENATED CHLOROFLUOROPROPANES BY HALOGEN EXCHANGE IN THE LIQUID AND VAPOUR PHASES AND THEIR ISOMER ANALYSES BY 19 F NMR SPECTROSCOPY

Article abstract of DOI:10.1016/S0022-1139(00)82937-1

The liquid phase fluorination of pentachlorotrifluoeropropane (1) and tetrachlorotetrafluoropropane (2) of defined isomer composition at atmospheric or autogenous pressure by means of the Henne-Swarts reagent yielded from 60 percent to 70 percent of tetrachlorotetrafluoropropane (2) and trichloropentafluoropropane (3).The vapour-phase fluorination of chlorofluoropropanes 1-3 with hydrogen fluoride catalysed by ferric salts on a charcoal support afforded chloropropanes 2 and 3 in addition to dichlorohexafluoropropane (4) in a yield of 13.5 percent to 79 percent.Simultaneusly an isomerization reaction took place in some cases.The isomer compositions of the starting substances and products were determined by means of 19F NMR spectroscopy.The NMR data of the isomers ar given and compared with the chemical shifts calculated using the published empirical method <1>.