peroxydes

Peroxydes, often written as peroxides in English, are chemical compounds that contain a peroxide functional group defined by an O–O single bond. The simplest member is hydrogen peroxide (H2O2). The term covers inorganic peroxides, such as sodium peroxide (Na2O2) and metal peroxides like barium peroxide (BaO2), as well as organic peroxides in which the peroxide moiety links two organic groups (R–O–O–R′). Hydroperoxides (ROOH) are closely related but are considered a different subclass, containing a hydroperoxy group.

The O–O bond in peroxides is relatively weak, and homolytic cleavage can generate reactive oxygen-centered radicals. This reactivity makes many peroxides useful as radical initiators in polymerization and as oxidants in chemical synthesis. Inorganic hydrogen peroxide serves as a widely used bleaching agent, oxidant, and antiseptic. Organic peroxides include dialkyl, diaryl, and acyl peroxides; many are highly reactive and, in several cases, shock- or heat-sensitive, requiring careful handling and storage.

Classification typically divides peroxides into inorganic and organic types. Organic peroxides encompass various subtypes, such as peroxide esters and peroxides used as polymerization initiators, for example di-tert-butyl peroxide or benzoyl peroxide. Hydroperoxides (ROOH) form a related family and are distinguished by the presence of a single O–OH unit rather than a peroxide bridge.

Safety and handling are important considerations, as peroxides are strong oxidizers and can pose risks of explosive decomposition under improper storage, heating, or friction, especially for concentrated organic peroxides. Concentrated hydrogen peroxide is caustic and can cause irritation.

Hydrogen peroxide was first isolated in 1818 by Louis Jacques Thénard. The term peroxides is widely used across chemistry and related fields to describe this broad class of oxygen–oxygen compounds.