Peroxycarboxylic acids peroxyacetic acid

Hydrolysis of Peroxycarboxylic Systems. Peroxyacetic acid [79-21-0] is produced commercially by the controlled autoxidation of acetaldehyde (qv). Under hydrolytic conditions, it forms an equiHbrium mixture with acetic acid and hydrogen peroxide. The hydrogen peroxide can be recovered from the mixture by extractive distillation (89) or by precipitating as the calcium salt followed by carbonating with carbon dioxide. These methods are not practiced on a commercial scale. Alternatively, the peroxycarboxyHc acid and alcohols can be treated with an estetifying catalyst to form H2O2 and the corresponding ester (90,91) (see Peroxides and peroxy compounds). 

The magnesium salt of monoperoxyphthalic acid is an alternative. Peroxyacetic acid, peroxybenzoic acid, and peroxytrifluoroacetic acid also are used frequently for epoxidation. All of the peroxycarboxylic acids are potentially explosive materials and require careful handling. Potassium hydrogen peroxysulfate, which is sold commercially as Oxone , is a convenient reagent for epoxidations that can be done in aqueous solution. 

The most widely used reaction in this category is the conversion of olefins to epoxides. In most cases, one of several peroxycarboxylic acids is used to effect oxidation. m-Chloroperoxybenzoic acid, which is commercially available or readily prepared and is a quite stable solid, is the most popular reagent. Peroxyacetic acid, peroxybenzoic acid, peroxytrifluoroacetic acid, and others, however, have also been used frequently. 

The most common laboratory method for the synthesis of epoxides from alkenes is oxidation with a peroxycarboxylic acid (a peracid), RCO3H. One peracid used for this purpose is peroxyacetic acid ... 

As a rule, alkenes do not react with 78-80 unless there is another reagent present—specifically, a transition metal. This reaction will not be discussed further. In sharp contrast, peroxycarboxylic acids such as 81 react directly with alkenes. Peroxycarboxylic acids 81 are named by adding the term peroxy to the name of the carboxylic acid (see Chapter 5, Section 5.9.3 and Chapter 16, Section 16.4). Using the common names, the peroxy analog of formic acid is peroxyformic acid (82), and others include peroxyacetic acid (83), peroxytrifiuo-roacetic acid (84), peroxybenzoic acid (85), and me a-chloroperoxybenzoic acid (abbreviated mCPBA, 86). Peroxycarboxylic acid 85 is a derivative of the aromatic carboxylic acid benzoic acid (PhCOOH), and the carboxylic acid precursor to 86 is clearly another aromatic carboxylic acid. (The nomenclature and structural features of benzoic acid and other aromatic carboxylic acid derivatives will be discussed in detail in Chapter 21, Section 21.2.) The salient feature of peroxyacids 82-86 is the presence of the electrophihc oxygen atom mentioned previously, which will react with an alkene. 

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