Highly selective metal fluoride catalysts for the dehydrohalogenation of 3-chloro-1,1,1,3-tetrafluorobutane

For the first time, dehydrochlorination and dehydrofluorination reactions are studied on the same substrate, 3-chloro-1,1,1,3-tetrafluorobutane, employing nanoscopic metal fluorides AlF₃, MgF₂, CaF₂, SrF₂, and BaF₂ as catalysts that are prepared according the fluorolytic sol-gel synthesis. AlF₃ is exclusively selective toward dehydrofluorination, whereas BaF₂ is 100% selective toward dehydrochlorination. The acid-base character of the catalysts is investigated and, as a result, mechanistic proposals for the dehydrofluorination and the dehydrochlorination are given. Thus, at high conversion level, selective catalysts for both dehydrofluorination and dehydrochlorination on the same substrate have been developed.