Peroxyformic acid carboxylic acids

Peroxyfomiic acid (perfomiic acid), HCO3H, is always prepared in situ from 25-30% hydrogen peroxide and 88 or 98-100% formic acid. At 26.5 C, the conversion of formic acid into peroxyformic acid requires approximately 1 h (as proven by analysis of peroxyformic acid and hydrogen peroxide contents [239]). The preparation of peroxyformic acid is carried out in the presence of the compounds to be oxidized, most often alkenes and double-bond-containing carboxylic acids. After an induction period of... 

Hydroxylation at double bonds of unsaturated carboxylic acids is accomplished stereoselectively by the same reagents as those used to hy-droxylate alkenes. syn Hydroxylation is carried out with potassium permanganate [101] or osmium tetroxide with hydrogen peroxide [130], sodium chlorate [310, 715], potassium chlorate [715], or silver chlorate [310] as reoxidant, anti Hydroxylation is achieved with peroxyacids, such as peroxybenzoic acid [310] or peroxyformic acid, prepared in situ from hydrogen peroxide and formic acid [101] (equation 472). 

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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