Peracid

A peracid, or peroxyacid, is a class of organic acids that contain a peroxide functional group adjacent to a carbonyl group, generally represented by the formula R-COOOH. The presence of the O–O bond makes peracids powerful oxidizing agents, capable of transferring electrophilic oxygen to substrates.

Peracids are typically prepared in situ by reacting a carboxylic acid with hydrogen peroxide in the presence of an acid catalyst. Common routes use acetic or benzoic acids as the carboxylate component, often in a suitable solvent system that stabilizes the resulting peracid. Examples of individual peracids include peracetic acid (CH3COOOH), perbenzoic acid (C6H5COOOH), and m-chloroperbenzoic acid (m-CPBA). These reagents are valued for their relative reactivity, which can be tuned by the choice of R group.

Major applications of peracids include epoxidation of alkenes to give epoxides, most notably via the Prilezhaev reaction, and the Baeyer-Villiger oxidation of ketones to esters. Peracids also oxidize sulfides to sulfoxides and sulfones and can participate in other oxygen-transfer transformations. Specific peracids such as m-CPBA are widely used in laboratory synthesis due to their stability and selectivity.

Safety and handling are important considerations. Peracids are generally unstable and can decompose violently under heat, shock, or contamination by bases or reducing agents. They are usually stored at low temperatures and used in situ or as solutions to reduce hazards. Appropriate protective equipment and procedures are required in their preparation and use.