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{{Short description|Chemical compounds with the structure R–O–O–R'}}
{{Short description|Chemical compounds with the structure R–O–O–R'}}

{{Other uses}}
{{Other uses}}
In [[chemistry]], '''peroxides''' are a group of [[Chemical compound|compounds]] with the structure {{chem2|R\sO\sO\sR}}, where the R's represent a radical (a portion of a complete molecule; not necessarily a [[free radical]]<ref>{{Cite web |title=Illustrated Glossary of Organic Chemistry |url=http://www.chem.ucla.edu/~harding/IGOC/R/r_group.html |access-date=June 19, 2024 |website=UCLA}}</ref>) and O's are single [[oxygen]] atoms.<ref>{{Greenwood&Earnshaw2nd}}</ref><ref>{{March6th}}</ref> Oxygen atoms are joined to each other and to adjacent elements through [[Single bond|single covalent bonds]], denoted by dashes or lines. The {{chem2|O\sO}} group in a peroxide is often called the '''peroxide group,''' though some nomenclature discrepancies exist. This linkage is recognized as a common [[polyatomic ion]], and exists in many molecules.
{{Chembox
| IUPACName = Peroxide
| SystematicName = Dioxidanediide
| OtherNames = Dioxide(2-)
|Section1={{Chembox Identifiers
| index_label=ion
| index1_label = inorganic
| index2_label = organic
| index3_label = group
| index4_label = hydroperoxy group
| CASNo = 14915-07-2
| CASNo_Ref = {{Cascite|changed|ChemSpider}}
| PubChem = <!--SID = 26697134 appears to be no CID-->
| ChemSpiderID = 14091
| ChEBI = 44785
| ChEBI1 = 24837
| ChEBI2 = 25702
| ChEBI3 = 25940
| ChEBI4 = 29792
| Gmelin = 486
| SMILES = [O-][O-]
| StdInChI = 1S/O2/c1-2/q-2
| StdInChIKey = ANAIPYUSIMHBEL-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| Formula = {{chem2|R\sO\sO\sR'}}
| O=2
}}
}}
[[File:Peroxide group v.2.png|thumb|upright|Types of peroxides, from top to bottom: peroxide ion, [[organic peroxide]], organic hydroperoxide, [[peracid]]. The peroxide group is marked in '''{{Font color|blue|blue}}'''. R, R<sup>1</sup> and R<sup>2</sup> mark hydrocarbon [[moiety (chemistry)|moieties]].]]


== General structure ==
In [[chemistry]], '''peroxides''' are a group of [[Chemical compound|compounds]] with the structure {{chem2|R\sO\sO\sR}}, where R is any [[Chemical element|element]].<ref>{{Greenwood&Earnshaw2nd}}</ref><ref>{{March6th}}</ref> The {{chem2|O\sO}} group in a peroxide is called the '''peroxide group''' or '''peroxo group'''. The nomenclature is somewhat variable.<ref>{{GoldBookRef|title=peroxides|file=P04510}}</ref>


The characteristic structure of a peroxide is the oxygen-oxygen covalent single bond, which connects the two main atoms together. In the event that the molecule has no chemical [[Substituent|substituents]], the peroxy group will have a [-2] [[Formal charge|net charge]]. Each oxygen atom has a charge of negative one, as 5 of its [[Valence electron|valence electrons]] remain in the outermost [[Atomic orbital|orbital shell]] whilst one is occupied in the [[covalent bond]]. Because of the nature of the covalent bond, this arrangement results in each atom having the equivalent of 7 valence electrons, [[Redox|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).
== Common forms ==
[[File:Peroxide_group_v.2.png|left|thumb|324x324px|Types of peroxides, from top to bottom: peroxide ion, [[organic peroxide]], organic hydroperoxide, [[peracid]]. The peroxide group is marked in '''blue'''. R, R<sup>1</sup> and R<sup>2</sup> mark hydrocarbon [[Moiety (chemistry)|moieties]].]]
The most common peroxide is [[hydrogen peroxide]] ({{chem2|H2O2}}), colloquially known simply as "peroxide". It is marketed as solutions in water at various concentrations. Many organic peroxides are known as well.
The most common peroxide is [[hydrogen peroxide]] ({{chem2|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:
{{multiple image

| direction = vertical
* [[Peroxy acid|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]].
| align = left
* [[Main group peroxides]], compounds with the linkage {{chem2|E\sO\sO\sE}} (E = [[main group element]]).{{multiple image
| header =
| direction = vertical
| width = 250
| align = right
| image1 = H2O2 gas structure.svg
| header =
| alt1 = {{chem2|O\sO}} bond length = 147.4 pm <br />{{chem2|O\sH}} bond length = 95.0 pm
| width = 215
| caption1 = Structure and dimensions of {{chem2|H2O2}}.
| image1 = H2O2 gas structure.svg
| alt1 = {{chem2|O\sO}} bond length = 147.4 pm <br />{{chem2|O\sH}} bond length = 95.0 pm
| caption1 = Structure and dimensions of {{chem2|H2O2}} in gas phase.
}}
}}
* [[Metal peroxide|Metal peroxides]], examples being [[barium peroxide]] ({{chem2|BaO2}}), [[sodium peroxide]] ({{chem2|Na2O2}}) and [[zinc peroxide]] ({{chem2|ZnO2}}).
* [[Organic peroxide|Organic peroxides]], compounds with the linkage {{chem2|C\sO\sO\sC}} or {{chem2|C\sO\sO\sH}}. One example is [[Tert-Butyl hydroperoxide|''tert''-butylhydroperoxide]].




In addition to hydrogen peroxide, some other major classes of peroxides are:
* [[Peroxy acid]]s, 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 {{chem2|E\sO\sO\sE}} (E = [[main group element]]).
* [[Metal peroxide]]s, examples being [[barium peroxide]] ({{chem2|BaO2}}), [[sodium peroxide]] ({{chem2|Na2O2}}) and [[zinc peroxide]] ({{chem2|ZnO2}}).
* [[Organic peroxide]]s, compounds with the linkage {{chem2|C\sO\sO\sC}} or {{chem2|C\sO\sO\sH}}. One example is [[tert-Butyl hydroperoxide|''tert''-butylhydroperoxide]].


==References==
== Nomenclature ==
The linkage between the oxygen molecules is known as a '''peroxy group''' (sometimes called '''peroxo group,''' '''peroxyl group, of peroxy linkage'''). The nomenclature of the peroxy group is somewhat variable,<ref>{{GoldBookRef|title=peroxides|file=P04510}}</ref> and exists as an exception to the rules of naming polyatomic ions. This is due to the fact that when it was discovered, it was believed to be monatomic.<ref>{{Cite web |date=2004 |title=Nomenclature |url=https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch2/names.html |access-date=March 25, 2024 |website=Purdue Division of Chemical Education}}</ref> The term was introduced by [[Thomas Thomson (chemist)|Thomas Thomson]] in 1804 for a compound combined with as much oxygen as possible,'''''<ref>{{Cite book |last=Thomson |first=Thomas |title=A System of Chemistry |date=1804 |publisher=Bell and Bradfute |year=1804 |edition=2nd |volume=1 |location=Edinburgh |publication-place=Edinburgh |publication-date=1804 |pages=division 1, page 103 |language=English |chapter=4 |via=Google books}}</ref>''''' or the oxide with the greatest quantity of oxygen.<ref>{{Cite web |last= Harper, Douglas. |title=Peroxide |url=https://www.etymonline.com/word/peroxide#:~:text=peroxide%20(n.),effective%20bleaching%20agent%20for%20hair). |website=Online Etymology Dictionary}}</ref>
{{Reflist}}


== References ==
<references />
{{Functional groups}}
{{Functional groups}}
{{Authority control}}
{{Authority control}}

Latest revision as of 17:56, 16 July 2024

In chemistry, peroxides are a group of compounds with the structure R−O−O−R, where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical[1]) and O's are single oxygen atoms.[2][3] Oxygen atoms are joined to each other and to adjacent elements through single covalent bonds, denoted by dashes or lines. The O−O group in a peroxide is often called the peroxide group, though some nomenclature discrepancies exist. This linkage is recognized as a common polyatomic ion, and exists in many molecules.

General structure

[edit]

The characteristic structure of a peroxide is the oxygen-oxygen covalent single bond, which connects the two main atoms together. In the event that the molecule has no chemical substituents, the peroxy group will have a [-2] net charge. Each oxygen atom has a charge of negative one, as 5 of its valence electrons remain in the outermost orbital shell whilst one is occupied in the covalent 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).

Common forms

[edit]
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.

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.

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).
    O−O bond length = 147.4 pm O−H bond length = 95.0 pm
    Structure and dimensions of H2O2 in gas phase.
  • 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.



Nomenclature

[edit]

The linkage between the oxygen molecules is known as a peroxy group (sometimes called peroxo 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 due to the fact that when it was discovered, it was believed to be monatomic.[5] The term was introduced by Thomas Thomson in 1804 for a compound combined with as much oxygen as possible,[6] or the oxide with the greatest quantity of oxygen.[7]

References

[edit]
  1. ^ "Illustrated Glossary of Organic Chemistry". UCLA. Retrieved June 19, 2024.
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  3. ^ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN 978-0-471-72091-1
  4. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "peroxides". doi:10.1351/goldbook.P04510
  5. ^ "Nomenclature". Purdue Division of Chemical Education. 2004. Retrieved March 25, 2024.
  6. ^ 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)
  7. ^ Harper, Douglas. "Peroxide". Online Etymology Dictionary.