Peracid oxidation peracetic acid

Percarboxylic acids have been used widely in Baeyer-Villiger oxidation. Peracetic acid is one of the most commonly used peracids distilled peracetic acid is employed commercially by Solvay Interox for the production of e-caprolactone.246 The use of distilled peracetic acid is essential, as it contains no strong protic acids which can catalyse polymerization of the resulting lactone and cause other side reactions. Figure 3.53 illustrates the use of pre-formed peracetic acid for the Baeyer-Villiger oxidation of ketones.247,248... 

Earlier reports have indicated that esters can form before significant amounts of acids accumulate (16). The Bayer-ViUiger oxidations of ketones with intermediate hydroperoxides and/or peracids have been suggested as ester forming mechanisms (34,56). However, the reactions of simple aUphatic ketones with peracetic acid are probably too slow to support this mechanism (57,58). Very early proposals for ester formation, although imaginative, appear improbable (59). 

Another method of preparing mercuric acetate is the oxidation of mercury metal using peracetic acid dissolved in acetic acid. Careful control of the temperature is extremely important because the reaction is quite exothermic. A preferred procedure is the addition of approximately half to two-thirds of the required total of peracetic acid solution to a dispersion of mercury metal in acetic acid to obtain the mercurous salt, followed by addition of the remainder of the peracetic acid to form the mercuric salt. The exothermic reaction is carried to completion by heating slowly and cautiously to reflux. This also serves to decompose excess peracid. It is possible and perhaps more economical to use 50% hydrogen peroxide instead of peracetic acid, but the reaction does not go quite as smoothly. 

Surprisingly, there are very few examples of successful fV-oxidation of pyrazoles. Simple fV-alkylpyrazoles generally do not react with peracids (B-76MI40402,77JCS(P1)672). The only two positive results are the peracetic acid (hydrogen peroxide in acetic acid) transformation of 1-methylpyrazoIe into 1-methylpyrazole 2-oxide (268) in moderate yield and the peroxy-trifluoroacetic acid (90% hydrogen peroxide in trifluoroacetic acid) transformation of 5-amino-l-methylpyrazoIe into l-methyl-5-nitropyrazoIe 2-oxide (269). 

Peracetic acid can be used to preferentially oxidize sulphoxides to sulphones in the presence of hydroxyl groups41, whilst attempted peracid oxidation of 2,6-diiodoaryl sulphoxides was not successful42. 

The reaction mechanism for the peracid oxidation of thiosulphinates is perhaps more complex than described above. A study of the low-temperature ( — 40 °C) peracetic acid oxidation of 2-methyl-2-propyl 2-methyl-2-propanethiosulphinate gave two products as shown in equation (81)196. During the reaction the a-disulphoxide was apparently detected by NMR spectroscopy. 

Peroxybenzoic acid readily oxidizes aryl and alkyl sulphoxides in acetone, methylene chloride or chloroform solutions, to the sulphone in high yield . The reaction is second order and acid catalysed as is the reaction with peracetic acid . The rate of oxidation is about five times faster than when peracetic acid is used. Other work considering the oxidation of sulphoxides with peracids gathered kinetic evidence and showed that the reaction was indeed second order and that the reaction involved nucleophilic attack by the sulphoxide sulphur atom on the peracid moiety. A further study by the same authors showed that with benzyl and phenyl alkyl sulphoxides the rate of reaction was very sensitive to the inductive effect of the alkyl group. Support for the nucleophilic attack by the sulphur atom on the peracid in acidic solution was forthcoming from other sources . ... 

Preparing peracetic acid by the action of hydrogen peroxide on acetic acid is as hazardous. If the temperature is too low, compounds accumulate and cause the medium to detonate. Using peracetic acid solution as an oxidant causes detonations when its concentration is too high or if evaporation is attempted. An accident happened during such an operation (see reaction below). The best way to eliminate this peracid at the end of the reaction is to heat it in a water bath at a temperature that should not exceed 50°C and under reduced pressure. 

Organic peracids are the most reliable and commonly used oxidizing reagents for various purposes in organic chemistry. Compared to common percarboxylic acids such as performic acid, peracetic acid, perbenzoic acid and m-chloroperbenzoic acid, the first sulfur peroxy acid, i.e. monopersulfuric acid , was reported earlier, already in 1891. 

The Baeyer-Villiger oxidation of acyl-substituted cyclobutanones 1 is reported to be very slow with ordinary peracids such as 3-chloroperoxybenzoic acid24- 31 37 38 and peracetic acid.24,36 Generally, reaction times of several weeks are needed to obtain acceptable yields of acyloxycy-... 

Oxidation with Stoichiometric Oxidants. Certain peracids reacting with alkanes yield alcohols. Peracetic acid,68 69 perbenzoic acid,70 m-CPBA,71,72 and nitroper-benzoic acids may be used. Alcohols or an equilibrium mixture of the alcohol and the trifluoroacetate77 are formed on the action of pertrifluoroacetic acid. A high degree of regioselectivity (better than 97%), specifically, preferential attack at the tertiary C—H bonds, is usually observed ... 

When nonactivated peracids such as peracetic acid or perbenzoic acid are used in oxidation of alkanes, the formation of methane and benzene, respectively, as well as evolution of C02 are observed. This indicates a radical mechanism 68,78... 

In the peracid process (Bayer-Degussa technology916) propionic acid is oxidized by hydrogen peroxide in the presence of H2S04 to yield perpropionic acid, which, in turn, is used to oxidize propylene to propylene oxide. The peracetic acid process (Daicel technology ) employs a mixture of acetaldehyde, ethyl acetate, and... 

The reaction mechanism for A-oxidation by performic acid has been studied by AMI calculation methods.174 The iminium salt A-mcthyl-3,4-dihydroisoquinolinium p-toluenesulfonate has been used to catalyse the oxidation of the azo dye calmagite by peracetic acid. The mechanism at pH 10 involves peracid oxidation of the quinolinium ion to form an oxaziridinium salt, which then acts as an oxygen transfer agent for oxidation of cahnagite.175 The presence of lithium salts affects the course of the reaction determining the formation of benzoyl peroxide and benzoic acid as final products in the oxidation of benzaldehyde by perbenzoic acid.176,177... 

The epoxidation reaction is achieved most conveniently by employing m-chloroperbenzoic acid (or perbenzoic acid) in a solvent such as chloroform. The use of other peracids, such as peracetic acid or pertrifluoroacetic acid, give lower yields of the oxirane since the oxide may be readily cleaved to form the monoester of the diol (e.g. Section 5.4.5, p. 547). 

The Lewis acidity of Zr in amorphous zirconium phosphate has been exploited for the Baeyer-Villiger oxidation of ketones with H202 as the oxidant (209). Excellent results are obtained for reaction in acetic acid. However, it is difficult to distinguish between the contributions of in situ formed peracetic acid and an inorganic Zr peracid. In the reaction in acetonitrile, the yields of oxidized products are modest ... 

Oxidation of Co(II) or Mn(II) complexes by peracids [reaction (106) or (107)] is a facile reaction.124 Reaction (108) proceeds much more slowly, if at all. Thus, in contrast to the reaction with alkyl hydroperoxides (see preceding section), during the decomposition of peracetic acid the cobalt catalyst is present largely as Co(III) in both chlorobenzene and acetic acid solutions. Peracids are intermediates in the autoxidation of aldehydes, but the direct oxidation of aldehydes is a more favorable pathway for the regeneration of the reduced form of the catalyst (see Section II.B.3.e). The predominance of Co(III) supports the reaction (109) as the slower step in both solvents. 

This hemiacetal type of peroxide has been isolated in fact, a commercial synthesis of peracetic acid is based upon formation of this material (11). These authors state that this peroxide decomposes spontaneously to two molecules of acetic acid and that the decomposition is slow at 0°C. but the rate increases rapidly as the temperature increases. Analogously in polymer oxidation aldehyde could be oxidized by peracid to the hemiperacetal intermediate which then breaks down to form two acid groups. 

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