ISOMERIZATION OF MONOHYDROPERFLUOROALKENES

Isomerization of monohydroperfluoro-1-alkenes HC(CF2)(n)CF=CF2 (n = 2 to 8) catalyzed by Lewis bases or acids (CsF, KHF2, and SbF5) under co nditions of thermodynamic control affords equilibrium mixtures of all of the possible isomers resulting from migration of the double bond al ong the carbon chain. Under conditions of kinetic control, isomerizati on through the action of SbF5 gives omega-H-perfluoro-2-alkenes. The s ubstantially higher proportion of cis-isomers in the resulting monohyd roperfluoroalkenes than in their perfluorinated analogs has been attri buted to the effect of an intramolecular hydrogen bond.