Isomerization of monohydroperfluoroalkenes

Isomerization of monohydroperfluoro-1-alkenes HC(CF₂)_nCF=CF₂ (n = 2 to 8) catalyzed by Lewis bases or acids (CsF, KHF₂, and SbF₅) under conditions of thermodynamic control affords equilibrium mixtures of all of the possible isomers resulting from migration of the double bond along the carbon chain. Under conditions of kinetic control, isomerization through the action of SbF₅ gives -H-perfluoro-2-alkenes. The substantially higher proportion ofcis-isomers in the resulting monohydroperfluoroalkenes than in their perfluorinated analogs has been attributed to the effect of an intramolecular hydrogen bond.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1614–1619, September, 1994.