Perfluoroalkyl peroxides

Recent Progress in Perfluoroalkylation by Radical Species with Special Reference to the Use of Bis(perfluoroalkanoyl)peroxides Yoshida, M, Kamigata, N J Fluorine Chem 49, 1-20 62 an c -I d... 

The monofluoromethylene group and difluoromethyl group m 1H perfluoro-alkanes and -cycloalkanes are oxidized at the C-H bond to perfluoroalkyl and perfluorocycloalkyl fluorosulfates by anodic oxidation m fluorosulfonic acid [J, 4] Two modifications of the method are used ox idation by fluorosulfonyl peroxide generated pnor to the reaction [J] (equation 2A) and direct electrolysis m the acid [i, 4] (equabons 2B and 3)... 

The addition of halogenated aliphatics to carbon-carbon double bonds is the most useful type of carbon-carbon bond forming synthetic method for highly halogenated substrates Numerous synthetic procedures have been developed for these types of reactions, particularly for the addition of perfluoroalkyl iodides to alkenes using thermal or photolytic initiators of free radical reactions such as organic peroxides and azo compounds [/]... 

Industrially, the perfluoroalkyl iodides by telomerization are mostly made by a batch system using peroxide initiators. However, the difficulty of mass production, and the production of hydrogen-containing byproducts in the process are disadvantageous [4]. In this study, a continuous process for the preparation of perfluoroalkyl iodides over nanosized metal catalysts in gas phase and the effects of the particle size on the catalytic activities of different the preparation methods and active metals were considered. 

J. P. DeYoung, J. Kalda, and J. M. DeSimone, Decomposition kinetics of perfluoroalkyl acyl peroxides in liquid and supercritical carbon dioxide, in preparation. 

Additions of perfluoroalkyl groups generated from perfluoroalkyl iodides (Rpl) and perfluoroacyl peroxides [RpC(0)00(0)CRp] have also been carried out [50]. Another usable source of CEj radicals is the stable [(CF3)2CF]2 CCF2CE3 radical (Scheme 6.8) [51]. As with alkyl radical additions, ESR spectroscopic investigations... 

Fluorooxy acids of sulfur, 2 123-127, 145 Ruoro(pentafluorosulfur) peroxide, 16 141 Fluoro(perfluoroalkyl) peroxides, 16 142-144 preparation of, 16 142, 143... 

Perfluoroalkylhalogenomercurates, 3 344-346 Perfluoroalkylmercuric iodides, 3 340 Perfluoroalkyl phosphorus acids, 3 382-387 Perfluoroalkyl tertiary amines, 16 26, 27 structural parameters, 16 27 Perfluoroamines preparation of, 3 356 properties of, 3 361-363 Perfluoro-/-butyl(fluorosulfuryl) peroxide, 16 126... 

The presence of a 9x-fluorine in a 11/l-hydroxy-A4-3-oxo steroid 10 results in completely stereospecific alkaline epoxidation with hydrogen peroxide to give 11 in a much slower reaction (4 d vs 4h) than that of the nonfluorinated analog.19 The nonfluorinated C = C bond in 3-perfluoroalkylated prop-1-ene 12 is epoxidized, with difficulty, in 7 days by 3-chloroperoxy-benzoic acid to give 13.20... 

Recent Progress in Perfluoroalkylation by Radical Species with Special Reference to the Use of Bis(perfluoroalkanoyl)peroxides ... 

Decomposition of perfluoroalkyl peroxide in the presence of trimethoxyvinylsilane gives the corresponding oligomers 152 (equation 126)219... 

Perfluoro-M-alkyl diacyl peroxides decompose homolytically to give perfluoroalkyl radicals under mild conditions, and radicals formed in such a manner have been used synthetically or as radical initiators for polymerizations [66,67]. 

In a series of papers in the early 1980s, Sokolov s group reported relative rate studies which were similar in nature to those of the early Szwarc studies. Sokolov generated various perfluoroalkyl radicals via thermal decomposition of the respective perfluoro diacyl peroxides in heptane containing various olefins [89] or arenes [90]. Determination of the ratio of olefin addition products to hydrogen abstraction products provided the relative rate data given in Table 4 [89]. 

Recent laser flash photolysis (LFP) studies have provided absolute rates of addition of perfluoro-n-alkyl radicals to a variety of alkenes in solution [ 114,115]. In these studies, C2Fj, C3F7, and n-C7F,5 were generated instantaneously by photolysis of the respective diacyl peroxides. The initially-formed perfluoroacyloxyl radicals decarboxylated rapidly to yield the perfluoroalkyl radicals, after which the additions of these radicals to styrene, a-methylstyrene, etc. were monitored directly via observation of the growth of UV absorption due to the transient benzylic radicals. 

Perfluoroalkyl iodides serve as the primary source of the propagating radicals in such additions, although there are situations where other precursors such as perfluoroalkyl sulfonyl bromides and diacyl peroxides may be used effectively. 

Ideal conditions for polymerization of a fluoroolefin are those where little, or better yet, no chain-transfer occurs. Thus perfluoroalkyl iodides are not used to initiate polymerizations. Instead, non-chain-transfer agents, particularly peroxide initiators, including perfluorodiacyl peroxides and ammonium persulfate, are used effectively for this purpose [67]. 

Lastly, electron transfer processes can also compete with nucleophilic acyl substitution in the reaction of perfluorodiacyl peroxides with Grignards [305]. Such a process can lead to a coupling of the Grignard with the perfluoroalkyl radical intermediate. (In contrast, benzyl lithium gives no perfluoroalkylation under the same conditions.)... 

Perfluoroalkyl radicals were generated according to a procedure developed by this research group, involving iodine abstraction from perfluoroalkyl iodides by phenyl radical (Equation 14.13) this latter derives from thermal decomposition of benzoyl peroxide (Equation 14.14). 

TABLE 1. Selected perfluoroalkyl peroxides and their effectiveness in initiating the polymerization of vinylidene fluoride. 

Neutral catalysts or catalyst precursors based on fluorinated ligand systems have been applied in compressed CO2 to a broad range of transformations such as Zn- and Cr-catalyzed copolymerization of epoxides and CO2 [53, 54], Mo-catalyzed olefin metathesis [9], Pd-catalyzed coupling reactions [43, 55, 56] and Pd-catalyzed hydrogen peroxide synthesis [57]. Rhodium complexes with perfluoroalkyl-substituted P ligands proved successful in hydroformylation of terminal alkenes [28, 42, 44, 58], enantioselective hydroformylation [18, 59, 60], hydrogenation [61], hydroboration [62], and polymerization of phenylacetylene... 

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