Preparation from perfluoroalkenes

Several perfluoroalkene derivatives have been made and used successfully in synthesis. Trifluorovinylmagnesium bromide and the lithium derivative may be obtained [39 1] from bromotrifluoroethene but preparation from HFC 134a, which involves metallation of trifluoroethene generated in situ, is now the more accessible route (see Section lA). However, direct metallation of fluorinated alkenes and fluorinated cycloalkenes has also been reported [26, 28] (Figure 10.9). 

Oleophilic/oleophobic fluorinated surfactants without a hydrophile, designed for use in hydrocarbon systems, are in a structural sense also nonionic fluorinated surfactants (see Section 1.8) for example, the semifluorinated alkanes [266-270], block polyethylene-polypropylene glycol ethers prepared with perfluoroalkene trimers [271], surfactants featuring an oligo(hexafluoropropene oxide) chain [272], and carboxamides and sulfonamides derived from A -(perfluorooctanesul-fonyl)piperazine [273]. 

Reaction of perfluoroaLkenes and hypochlorites has been shown to be a general synthesis of perfluoroepoxides (32) (eq. 7). This appears to be the method of choice for the preparation of epoxides from internal fluoroalkenes (38). Excellent yields of HFPO from hexafluoropropylene and sodium hypochlorite using phase-transfer conditions are claimed (34). 

Preparation of nitronitroso dimers from a variety of straight chain alkenes has been patented. " The reactions of nitric oxide with alkenes are extremely complex (e.g. isobutylene) and are rarely usefiil. Perfluoroalkenes add nitric oxide at room temperature in the da tetraflucMoethylene gives ONCF2CF2NO (68%) the reaction with perfluoropropene is more complex. ... 

Ultraviolet irradiation of perfluorocarbons in the presence of (C5Me5)2Fe and Li03SCF3 as a fluoride acceptor provides an exceptionally mild system [80] to prepare perfluoroalkenes from perfluoroalkanes and the chemistry can be made catalytic with respect to iron by using zinc to reduce [(C5Me5)2Fe]+(Scheme 6). 

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