Inchemistry,peroxides are a group ofcompounds with the structureR−O−O−R, where the R's represent a radical (a portion of a complete molecule; not necessarily afree radical[1]) and O's are singleoxygen atoms.[2][3] Oxygen atoms are joined to each other and to adjacent elements throughsingle covalent bonds, denoted by dashes or lines. TheO−O group in a peroxide is often called theperoxide group, though some nomenclature discrepancies exist. This linkage is recognized as a commonpolyatomic ion, and exists in many molecules.
The characteristic structure of any regular peroxide is the oxygen–oxygen covalent single bond, which connects the two main atoms together. In the event that the molecule has no chemicalsubstituents, the peroxide group will have a [−2]net charge. Each oxygen atom has a charge of negative one, as 5 of itsvalence electrons remain in the outermostorbital shell whilst one is occupied in thecovalent bond. Because of the nature of the covalent bond, this arrangement results in each atom having the equivalent of 7 valence electrons,reducing the oxygens and giving them a negative charge. This charge is affected by the addition of other elements, with the properties and structure changing depending on the added group(s).
Types of peroxides, from top to bottom: peroxide ion,organic peroxide, organic hydroperoxide,peracid. The peroxide group is marked inblue. R, R1 and R2 mark hydrocarbonmoieties.
The most common peroxide ishydrogen peroxide (H2O2), colloquially known simply as "peroxide". It is marketed as solutions in water at various concentrations. Many organic peroxides are known as well.
In addition to hydrogen peroxide, some other major classes of peroxides are:
The linkage between the oxygen molecules is known as aperoxy group (sometimes calledperoxo group,peroxyl group, of peroxy linkage). The nomenclature of the peroxy group is somewhat variable,[4] and exists as an exception to the rules of naming polyatomic ions. This is because, when it was discovered, it was believed to be monatomic.[5] The term was introduced byThomas Thomson in 1804 for a compound combined with as much oxygen as possible,[6] or the oxide with the greatest quantity of oxygen.[7]
^"Nomenclature".Purdue Division of Chemical Education. 2004. RetrievedMarch 25, 2024.
^Thomson, Thomas (1804). "4".A System of Chemistry. Vol. 1 (2nd ed.). Edinburgh: Bell and Bradfute. pp. division 1, page 103 – via Google books.{{cite book}}: CS1 maint: date and year (link)
