Fluoro peroxy

A more efficient agent than peroxy compounds for the epoxidation of fluoro-olefins with nonfluonnated double bond is the hypofluorous acid-acetomtrile complex [22] Perfluoroalkylethenes react with this agent at room temperature within 2-3 h with moderate yields (equation 13), whereas olefins with strongly electron-deficient double bond or electron-poor, sterically hindered olefins, for example l,2-bis(perfluorobutyl)ethene and perfluoro-(l-alkylethyl)ethenes, are practically inert [22] Epoxidation of a mixture of 3 perfluoroalkyl-1-propenes at 0 C IS finished after 10 mm in 80% yield [22] The trifluorovinyl group in partially fluorinated dienes is not affected by this agent [22] (equation 13)... 

Bcnzaldehydes with fluoro substituents (monofluoro, trifluoromethyl) on the aromatic ring are readily oxidized to peroxy compounds 1 with 30% hydrogen peroxide, while the oxidation with concentrated hydrogen peroxide leads to geminal hydroxy hydroperoxides 2.185... 

Fluoro-2.2-dinitroethyl)aniine is not affected by hydrogen peroxide in aqueous or methanolic solution, even in the presence of transition metal catalysts.218 On the other hand, it is oxidized by 3-chloroperoxybenzoic acid to the corresponding hydroxylamine 8, which on further oxidation by a second equivalent of the peroxy acid or bromine gives an oxime (vide infra).118... 

Biological oxidation of a 2-aminoimidazole gives poor yields (<38%), and none at all with l-alkyl-2-aminoimidazoles. Nor will oxidation with peroxy-trifluoroacetic acid work It is, however, satisfactory for the oxidation of 4-aminoiniidazoles (which are usually rather unstable compounds). ITie most common way of making 2-nitroi midazoles is from the diazonium fluoro-borates subjected to the Gattermann reaction (see Section 7.3). Yields vary from 20 to 50% [6, 7], and again are dependent on the availability of the 2-aminoimidazoles (see Section 8.2.2). 

The reaction stoichiometries, product profiles, and apparent second-order rate constants for the combination of perfluoroaromatic molecules (and several hydro and dihydro derivatives) with excess superoxide ion in dimethylformamide are summarized in Table 7-1. The primary product from the combination of C6F6 with 2 equivalents of O2-- is CeEgOO on the basis of the F-NMR spectrum of the product solution and the mass spectrum for the major peak from the capillary GC of the product solution.24 Similar analyses of the product solutions for the other fluoro substrates are consistent with a peroxide product from the displacement of a fluoride ion. A reasonable first step for these oxygenations is nucleophilic addition of O2 - to the polyfluoroaromatic. Subsequent loss of fluoride ion will give an aryl peroxy radical, which will be reduced by a second O2-- to the aryl peroxide product. This reaction sequence (with the initial nucleophilic displacement the rate-determining step) is analogous to that observed for chlorohydrocarbons and polychlorobenzenes (Scheme 7-8). However, the peroxo product of the latter systems is an effective nucleophile that attacks a second substrate molecule (or an adjacent aryl chlorine... 

In general, alkyl radicals trapped in polymer materials convert to peroxy radicals when oxygen molecules are introduced. The disappearance of the double quintet due to the chain type fluoro alkyl radicals in polytetrafluoroethylene (PTFE) described... 

Reaction (C) The reaction is important in a chain mechanism during the auto oxidization process. Direct observation of the reaction was successfully carried out by Hori et al. [32] for a urea-polyethylene complex (UPEC). Figure 7.30 shows the variations of ESR spectra for peroxy radicals in the UPEC due to heat treatment in vacuum at 361 K. Spectrum (a) was obtained from peroxy radicals and spectrum (d) was that obtained from alkyl radicals as shown in Section 7.4.1. Figure 7.31 shows the variation of the concentrations of various radicals with the time of heat treatment at 361 K. It was found that 20% of the radicals decayed, but ca. 80% of the decaying peroxy radicals were converted into alkyl radicals. A few authors reported that peroxy radicals trapped in polytetraflu-oroethylene converted into alkyl fluoro radicals by heat treatment in a similar manner. Some authors claimed that the back reaction of Eq. (7.16) occurred in that case ... 

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