Editing Methyl radical (section)

== Production ==
===Biosynthesis===
Some [[radical SAM]] enzymes generate methyl radicals by reduction of S-adenosylmethionine.<ref>{{cite journal|author1=Ribbe, M. W. |author2=Hu, Y. |author3=Hodgson, K. O. |author4=Hedman, B. |title=Biosynthesis of Nitrogenase Metalloclusters|journal=Chemical Reviews|year=2014|volume=114|issue=8|pages=4063–4080|doi=10.1021/cr400463x|pmc=3999185|pmid=24328215}}</ref>

=== Acetone photolysis ===
It can be produced by the ultraviolet photodissociation of [[acetone]] vapour at 193&nbsp;nm:<ref name=Hall1991>{{cite journal|last1=Hall|first1=G. E.|last2=Vanden Bout|first2=D.|last3=Sears|first3=Trevor J.|title=Photodissociation of acetone at 193 nm: Rotational- and vibrational-state distributions of methyl fragments by diode laser absorption/gain spectroscopy|journal=The Journal of Chemical Physics|date=1991|volume=94|issue=6|page=4182|doi=10.1063/1.460741|publisher=[[AIP Publishing]]|bibcode = 1991JChPh..94.4182H |url=https://zenodo.org/record/1232934}}</ref>
:{{Chem|C|3|H|6|O}} → CO + 2&nbsp;{{Chem|CH|3|•}}

=== Halomethane photolysis ===
It is also produced by the ultraviolet dissociation of [[halomethane]]s:
:{{Chem|CH|3|X}} → X<sup>•</sup> + {{Chem|CH|3|•}}

=== Methane oxidation ===
{{Details|Atmospheric methane#Removal processes}}
It can also be produced by the reaction of [[methane]] with the [[hydroxyl radical]]: 
:OH<sup>•</sup> + CH<sub>4</sub> → {{Chem|CH|3|•}} + H<sub>2</sub>O
This process begins the major removal mechanism of methane from the atmosphere.  The reaction occurs in the [[troposphere]] or [[stratosphere]]. In addition to being the largest known sink for atmospheric methane, this reaction is one of the most important sources of water vapor in the upper atmosphere.

This reaction in the [[troposphere]] gives a methane lifetime of 9.6 years. Two more minor sinks are soil sinks (160 year lifetime) and stratospheric loss by reaction with <sup>•</sup>OH, <sup>•</sup>Cl and <sup>•</sup>O<sup>1</sup>D in the stratosphere (120 year lifetime), giving a net lifetime of 8.4 years.<ref name="Trace Gases">{{cite web
| url=http://www.grida.no/climate/ipcc_tar/wg1/134.htm#4211
| title=Trace Gases: Current Observations, Trends, and Budgets
| work=Climate Change 2001, IPCC Third Assessment Report
| publisher=IPCC/United Nations Environment Programme}}</ref>

=== Azomethane pyrolysis ===
Methyl radicals can also be obtained by [[pyrolysis]] of [[Azo compound#Alkyl azo compounds|azomethane]], CH<sub>3</sub>N=NCH<sub>3</sub>, in a low-pressure system.