Peroxide (O2 2−) — structure, types, uses and safety

Peroxide denotes the O2 2− ion or compounds with an O–O bond. Often strong oxidizers, peroxides occur as inorganic salts and organic derivatives (including hydrogen peroxide) with broad industrial uses and special hazards.

Overview

Peroxide commonly refers to the dianion O2 2− or to chemical compounds that contain the characteristic O–O linkage. In ionic form it is an ion, but more often the term is used for salts and molecular species in which two oxygen atoms are joined by a single bond. Peroxide species can affect the oxidation state of other substances and so participate in redox chemistry.

Structure and chemical properties

The peroxide group contains an oxygen–oxygen single bond that is relatively weak compared with the O=O double bond of molecular oxygen. Because of its bonding and electron distribution, a peroxide can act either as a reducing agent or as an oxidizing agent, though it is frequently observed to behave as an oxidizer. Peroxides undergo redox transformations: they may be reduced to oxide species such as O2− or converted to molecular oxygen by decomposition. Conversion to simple oxide forms is also possible under suitable conditions.

Types and notable examples

Peroxides appear in both inorganic and organic chemistry.

Inorganic peroxides: The best-known example is hydrogen peroxide, H2O2, which is widely used in dilute and concentrated forms. Other inorganic examples include metal peroxides such as barium peroxide and alkali/alkaline earth peroxides used in specialty applications.
Organic peroxides: Compounds where the O–O unit is bonded to carbon-containing groups are classified as organic peroxides. These species range from useful polymerization initiators to highly unstable and potentially explosive materials; see organic peroxide safety guidance.

Uses and applications

Peroxides serve many roles across industry and laboratory practice. Common applications include bleaching and whitening (paper, textiles, hair), disinfection and antisepsis in dilute hydrogen peroxide solutions, initiation of polymerization reactions, and certain chemical oxygen generation and propellant systems. Historically some metal peroxides were used to supply oxygen in early oxygen-production methods.

Safety, risks, and handling

Peroxides can decompose exothermically, releasing oxygen and heat, and some organic peroxides are shock- or heat-sensitive. Accumulation of peroxide residues in susceptible solvents (for example ethers) can create explosive hazards; periodic testing and safe disposal are standard precautions. Storage guidelines include keeping peroxides cool, avoiding contamination, and using stabilizers or inhibitors when appropriate.

Notes

Peroxides are chemically versatile: their reactivity underpins useful industrial chemistry but also requires respect for their potential hazards. For further technical details and safety standards consult specialized chemical safety resources and material safety data sheets.