The addition of 0.1 M quaternary ammonium halide to a solution of 20% trifluoroacetic acid in methylene chloride causes a large rate increase in the reaction of simple alkenes leading to a mixture of alkyl halides and trifluoroacetates. The mechanism is proposed to involve a halide assisted protonation of the alkene which produces a carbocation intermediate sandwiched between the attacking halide ion and the trifluoroacetate ion. At higher ...
