Fluoroketones as Catalysts

Epoxidations with 60 % H2O2 in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), catalyzed by hexafluoroacetone - yield [%], reaction time - 

Reaction conditions alkene, 1 M in HFIP 2 eq. 60 % H2O2 0.05 eq. Na2HP04i 5 moi-% hexafluoroacetone room temperature. 

3 Bisepoxide, 3 % cymene was also formed. )2,3-Epoxide was formed exclusively. 

At ambient temperature and pressure, hexafluoroacetone is a (toxic) gas, and catalyst recovery is impractical. As a nonvolatile alternative, Sheldon et cd. employed perfluoroheptadecan-9-one. After completion of the epoxidation, this catalyst can be recovered from halogenated solvents such as dichloroethane or TFE by simple cooling of the reaction mixture [39]. Furthermore, this long-chain perfluorinated ketone has the potential for immobilization in fluorous phases. When appHed to epoxidation with perfluoroheptadecan-9-one as catalyst, TFE gave yields of epoxide comparable to those obtained in dichloroethane. However, to achieve good yields of add-sensitive epoxides, buffering by Na2HP04 was necessary. 

Fluorinated alcohols, and in particular HFIP, have also proven beneficial for epoxidations of alkenes using persulfate (Oxone) as the terminal oxidant and fluoroketones as catalysts [9, 10]. Under these conditions, the fluorinated ketones are converted to dioxiranes, which are the active epoxidizing spedes. Typical catalysts 

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