Isomerization of halopolyfluoroalkanes by the action of aluminum chlorofluoride

A combination of aluminum chlorofluoride (ACF)/fluoroolefin is an effective catalytic system for isomerization of vic-dichloroperfluoroalkanes into gem-isomers. For example, the isomerization of 1,2-dichloro-F-propane in the presence of catalytic amounts of ACF and hexafluoropropene proceeds at 130 degrees C giving 2,2-dichloro-F-propane in high yield. This catalytic system is also effective for converting cyclic 1,2-dichloro-F-cycloalkanes into 1,1-dichloro-F-cycloalkanes. Dibromo-F-alkanes are more reactive and rearrange under the action of ACF alone at 25-100 degrees C. Primary monoiodo- and monobromo-F-alkanes in the presence of ACF are converted into secondary isomers in moderate yields. (C) 1998 Elsevier Science S.A. All rights reserved.