Reactions involving fluoride ion. Part I. The polyfluoroalkylation of fluorinated aromatic systems

Abstract

Highly fluorinated aromatic compounds and their derivatives will react with carbanions produced from fluorinated olefins and fluoride ion, with the formation of polyfluoroalkyl derivatives, in a process which is the nucleophilic equivalent of the Friedel-Crafts reaction in hydrocarbon chemistry. Reaction occurs between hexafluoropropene and pentafluoropyridine, pentafluoronitrobenzene, and other activated systems like octafluorotoluene, pentafluorobenzonitrile, and methyl pentafluorobenzoate. Polysubstitution is achieved by increase in the pressure of the olefin, and CF₃CF₂^– is a more effective nucleophile than (CF₃)₂CF^–. Potassium or caesium fluoride may be used for initiation and, as solvents, tetraglyme and sulpholan are better than dimethylformamide, diglyme, and triglyme.