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	~~In [[chemistry]]~~, '''radical initiators''' are substances that can produce [[radical (chemistry)\|radical species]] under mild conditions and promote [[radical reaction]]s.<ref>{{JerryMarch}}</ref> These substances generally possess weak bonds—bonds that have small [[bond dissociation energy\|bond dissociation energies]]. Radical initiators are utilized in industrial processes such as [[polymer]] synthesis. Typical examples are [[halogen]] [[molecule]]s, [~~[azo compound]]s, and [[organic peroxide\|organic and inorganic peroxides]]s.<ref>{{March6th}}<~~/~~ref>~~		27 year old Market Study Analyst Rusty Golden from Chase, has many passions that include bonsai trees, property developers [http://www.gametabs.net/forum/topic/65863 house for sale in singapore] singapore and fish keeping. Discovers the charm in traveling to destinations across the entire world, recently only returning from Armenian Monastic Ensembles of Iran.

	~~==Major types of initiation reaction==~~
	*[[Halogen]]s undergo the [[homolysis (chemistry)\|homolytic fission]] relatively easily. [[Chlorine]], for example, gives two chlorine radicals (Cl•) by irradiation with [[ultraviolet\|ultraviolet light]]. This process is used for [[Free-radical halogenation\|chlorination]] of [[alkane]]s.

	*[[Azo compound]]s (R-[[nitrogen\|N]]=[[nitrogen\|N]]-R') can be the precursor of two [[carbon]]-centered radicals (R• and R'•) and [[nitrogen]] gas upon heating and/~~or by irradiation. For example, [[Azobisisobutyronitrile\|AIBN]] and [[ABCN]] yield isobutyronitrile and cyclohexanecarbonitrile radicals, respectively~~.
	~~:[[Image:AIBN-radical-2D~~.~~png\|400px\|AIBN initiator]]~~

	*[[Organic peroxide]]s each have a peroxide bond (-[[oxygen\|O]]-[[oxygen\|O]]-), which is readily cleaved to give two [[oxygen]]-centered radicals. The oxyl radicals are unstable and believed to be transformed into relatively stable [[carbon]]-centered radicals. For example, [[Di-tert-butyl peroxide\|di-''tert''-butyl peroxide]] (<sup>''t''</~~sup>[[butyl\|Bu]][[oxygen\|OO]]<sup>''t''<~~/~~sup>[[butyl\|Bu]]) gives two ''t''-butanoyl radicals (<sup>''t''<~~/~~sup>[[butyl\|Bu]][[oxygen\|O]~~]•) and the ~~radicals become [[methyl]] radicals ([[carbon\|C]][[hydrogen\|H]]<sub>3</sub>•) with~~ the loss of [[acetone]]. [[Benzoyl peroxide]] (([[phenyl\|Ph]][[carbon\|C]][[oxygen\|OO]])<sub>2</sub>) generates benzoyloxyl radicals ([[phenyl\|Ph]][[carbon\|C]][[oxygen\|OO]]•), each of which loses [[carbon dioxide]] to be converted into a [[phenyl]] radical ([[phenyl\|Ph]]•). [[Methyl ethyl ketone peroxide]] is also common, and [[acetone peroxide]] is on rare occasions used as a radical initiator, ~~too.~~

	*Inorganic peroxides function analogously to organic peroxides. Many polymers are often produced from the alkenes upon initiation with [[peroxydisulfate]] salts. In solution, peroxydisulfate dissociates to give sulfate radicals:<ref name = Ullmann>{{Ullmann \| title = Peroxo Compounds, Inorganic \| author = Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort \| doi = 10.1002/14356007.a19_177.pub2}}</ref>
	~~:: [O<sub>3</sub>SO-OSO<sub>3</sub>]<sup>2-</sup> <math>\overrightarrow{\leftarrow}</math> 2 [SO<sub>4</sub>]<sup>-</sup>~~
	~~The sulfate radical adds to an alkene forming radical sulfate esters, e.g. <sup>.</sup>CHPhCH<sub>2</sub>OSO<sub>3</sub><sup>-</sup>, that add further alkenes via formation~~ of ~~C-C bonds~~. ~~Many styrene and fluoroalkene polymers are produced in this way.~~

	* In atom transfer radical polymerization (ATRP) carbon-halides reversibly generate organic radicals in the presence of [[transition metal]] [[catalyst]].
	[[Image:ATRP general.png\|thumb\|600px\|General ATRP Reaction. <span style="color: blue">A.</span> Initiation. <span style="color: blue">B.</span> Equilibrium with dormant species. <span style="color: blue">C.</span>Propagation]]

	~~==Safety==~~
	~~Some radical initiators such as [[azo compound]]s and [[peroxide]]s are often unstable. They are often stored cold.~~

	~~==References==~~
	~~{{Reflist}}~~

	~~{{DEFAULTSORT:Radical Initiator}}~~
	~~[[Category:Radical initiators\| ]]~~

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In [[chemistry]], '''radical initiators''' are substances that can produce [[radical (chemistry)|radical species]] under mild conditions and promote [[radical reaction]]s.<ref>{{JerryMarch}}</ref> These substances generally possess weak bonds—bonds that have small [[bond dissociation energy|bond dissociation energies]]. Radical initiators are utilized in industrial processes such as [[polymer]] synthesis. Typical examples are [[halogen]] [[molecule]]s, [[azo compound]]s, and [[organic peroxide|organic and inorganic peroxides]]s.<ref>{{March6th}}</ref>

==Major types of initiation reaction==
*[[Halogen]]s undergo the [[homolysis (chemistry)|homolytic fission]] relatively easily. [[Chlorine]], for example, gives two chlorine radicals (Cl•) by irradiation with [[ultraviolet|ultraviolet light]]. This process is used for [[Free-radical halogenation|chlorination]] of [[alkane]]s.

*[[Azo compound]]s (R-[[nitrogen|N]]=[[nitrogen|N]]-R') can be the precursor of two [[carbon]]-centered radicals (R• and R'•) and [[nitrogen]] gas upon heating and/or by irradiation. For example, [[Azobisisobutyronitrile|AIBN]] and [[ABCN]] yield isobutyronitrile and cyclohexanecarbonitrile radicals, respectively.
:[[Image:AIBN-radical-2D.png|400px|AIBN initiator]]

*[[Organic peroxide]]s each have a peroxide bond (-[[oxygen|O]]-[[oxygen|O]]-), which is readily cleaved to give two [[oxygen]]-centered radicals. The oxyl radicals are unstable and believed to be transformed into relatively stable [[carbon]]-centered radicals. For example, [[Di-tert-butyl peroxide|di-''tert''-butyl peroxide]] (''t''[[butyl|Bu]][[oxygen|OO]]''t''[[butyl|Bu]]) gives two ''t''-butanoyl radicals (''t''[[butyl|Bu]][[oxygen|O]]•) and the radicals become [[methyl]] radicals ([[carbon|C]][[hydrogen|H]]3•) with the loss of [[acetone]]. [[Benzoyl peroxide]] (([[phenyl|Ph]][[carbon|C]][[oxygen|OO]])2) generates benzoyloxyl radicals ([[phenyl|Ph]][[carbon|C]][[oxygen|OO]]•), each of which loses [[carbon dioxide]] to be converted into a [[phenyl]] radical ([[phenyl|Ph]]•). [[Methyl ethyl ketone peroxide]] is also common, and [[acetone peroxide]] is on rare occasions used as a radical initiator, too.

*Inorganic peroxides function analogously to organic peroxides. Many polymers are often produced from the alkenes upon initiation with [[peroxydisulfate]] salts. In solution, peroxydisulfate dissociates to give sulfate radicals:<ref name = Ullmann>{{Ullmann | title = Peroxo Compounds, Inorganic | author = Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort | doi = 10.1002/14356007.a19_177.pub2}}</ref>
:: [O3SO-OSO3]2- <math>\overrightarrow{\leftarrow}</math> 2 [SO4]-
The sulfate radical adds to an alkene forming radical sulfate esters, e.g. .CHPhCH2OSO3-, that add further alkenes via formation of C-C bonds. Many styrene and fluoroalkene polymers are produced in this way.

* In atom transfer radical polymerization (ATRP) carbon-halides reversibly generate organic radicals in the presence of [[transition metal]] [[catalyst]].
[[Image:ATRP general.png|thumb|600px|General ATRP Reaction. A. Initiation. B. Equilibrium with dormant species. C.Propagation]]

==Safety==
Some radical initiators such as [[azo compound]]s and [[peroxide]]s are often unstable. They are often stored cold.

==References==
{{Reflist}}

{{DEFAULTSORT:Radical Initiator}}
[[Category:Radical initiators| ]]

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en>Surv1v4l1st: /* Jewelry */ Typograhic