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.