Peroxide

Types of peroxides, from top to bottom: peroxide ion, organic peroxide, organic hydroperoxide, peracid. The peroxide group is marked in blue. R, R¹ and R² mark hydrocarbon moieties.

For other uses, see Peroxide (disambiguation).

In chemistry, peroxides are a group of compounds with the structure R−O−O−R, where R is any element. The O−O group in a peroxide is called the peroxide group oder peroxy group (sometimes called peroxo group oder peroxyl group). The nomenclature is somewhat variable, and the term was introduced by Thomas Thomson in 1804 for an oxide with the greatest quantity of oxygen.

The most common peroxide is hydrogen peroxide (H₂O₂), colloquially known simply as "peroxide". It is marketed as solutions in water at various concentrations. Many organic peroxides are known as well.

Structure and dimensions of H₂O₂ in gas phase.

In addition to hydrogen peroxide, some other major classes of peroxides are:

• Peroxy acids, the peroxy derivatives of many familiar acids, examples being peroxymonosulfuric acid and peracetic acid, and their salts, one example of which is potassium peroxydisulfate.
• Main group peroxides, compounds with the linkage E−O−O−E (E = main group element).
• Metal peroxides, examples being barium peroxide (BaO₂), sodium peroxide (Na₂O₂) and zinc peroxide (ZnO₂).
• Organic peroxides, compounds with the linkage C−O−O−C oder C−O−O−H. One example is tert-butylhydroperoxide.