Peroxy acids and related compounds

The acyl derivatives of hydrogen peroxide have been widely studied and safely used even on a large scale. Nevertheless they should always be handled with care. In particular, they should not be ground, heated in a closed container, inhaled as vapour or ingested as dust. 

Peroxy acids and diacyl peroxides are mono- and di-acyl derivatives of hydrogen peroxide. Peroxy acids form esters of which the t-butyl compounds are the best known. In contrast to carboxylic acids which form intermolecular hydrogen-bonded dimers, the peroxy acids exist as intramolecular hydrogen-bonded monomers. This leads to several differences in the properties of these two types of acids. 

Peroxy acids are useful oxidizing agents and are generally analysed on the basis of their ability to oxidize iodide ion to iodine which can be determined titrimetrically or colorimetrically. They also oxidize alkenes to epoxides, ketones to esters or lactones, thioethers to sulphoxides and sulphones, and tertiary amines to amine oxides. 

The melting points of several peroxyacids are given in Table 10.5. 

The most important route to the peroxy acids (formerly called peracids) requires establishment of the equilibrium shown in the following equation  

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