Hexafluoropropene reactions with electrophiles

Systems with perfluoroalkyl groups directly attached to the double bond are particularly unreactive towards electrophiles but reaction of hexafluoropropene (HFP) with SbFs leads to a perfluoroallyl cation, which then reacts with another molecule of HFP to give a dimer, probably by an electrophilic process [168] (Figure 7.51) that is analogous to that described earlier for 1,1,1-trifluoropropene [169], (Chapter 4, Section VIB). Similar addition and isomerisation reactions, which proceed via carbocationic intermediates, are given in Figure 7.52 [170-172]. 

Tetrafluoroethyl)pyridines can be prepared using an unusual reaction of the pyridine oxides with electrophilic fluoroolefins, such as hexafluoropropene (HFP). This reaction discovered by Mailey and Ocone, was further expanded by the Haszeldine group and recently was extensively studied by Makosza et al. The reaction between heterocyclic A-oxides and HFP rapidly proceeds in DMF at ambient temperature and atmospheric pressure, resulting in the formation of the corresponding 2-(l,l,l,2-tetrafluoroethyl)- heterocycles 86-88 (Fig. 7.30). ... 

Reactions of perfluorinated alkenes, such as hexafluoropropene, with fluoride ion give perfluoroalkylcarbanions which can act as nucleophiles in S Ar reactions with perfluoroheteroaromatic systems (Fig. 8.13). These reactions are another example of mirror-image chemistry and reflect well-known Friedel-Crafts reactions of hydrocarbon systems that proceed by reaction of the corresponding electrophile and carbocationic intermediates. Poly substitution processes are possible and, indeed, all five fluorine atoms may be replaced upon reaction with an excess of tetrafluoroethylene and fluoride ion. ... 

The direction of iodine monofluoride addition to hexafluoropropene and, 1,1-di-fluoroethene suggests an electrophilic reaction mechanism. However, chlorotrifluoroethene gives a mixture of isomers both with iodine monofluoridc and with bromine monofluoride .1 0 The reactions of fluoroalkenes with bromine monofluoride proceed too quickly and for this reason they are conducted in l,l,2-trichloro-l,2,2-trifluoroethane though this hampers the isolation of addition products. 

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