View source for Methyl group



==Overview==

[[Image:Methyl group.jpg|thumb|right|Methyl group]]
In [[chemistry]], a '''methyl group''' is a [[hydrophobic]] [[alkyl]] [[functional group]] derived from [[methane]] CH<sub>4</sub>). It has the [[chemical formula|formula]] -CH<sub>3</sub> and is very often abbreviated as '''-Me''' in the structure of a molecule. This [[hydrocarbon]] unit can be found in many [[organic compound]]s. It is customarily written as H<sub>3</sub>C when on the left of a bond; for example, [[ethane]] is represented as H<sub>3</sub>C-CH<sub>3</sub>.

Methyl groups can be incorporated in organic compounds by an [[Nucleophilic substitution|S<sub>N</sub>2 reaction]] on [[iodomethane]], or by the reaction of [[methyl lithium]] or MeMgCl with a carbon atom that is substituted with a [[leaving group]]. 

{{see also|methylation}}

==Reactivity==
The introduction of methyl groups as new substituents in a compound usually increases the lipophilicity of the compound and reduces its water solubility. It should improve the ease of absorption of the analogue into a biological membrane but will make its release from biological membranes into the aqueous media more difficult. The incorporation of a methyl group can have one of three general effects on the rate of [[metabolism]] of an analogue:
# an increased rate of metabolism due to [[oxidation]] of the methyl group
# an increase in the rate of metabolism due to demethylation by the transfer of the methyl group to another compound, or a reduction of the analogue.

Chemically, the reactivity of a methyl group depends partially on what it is attached to. For example, when a methyl group is part of an [[alkane]], it is extremely unreactive and resists all but the strongest of acids, bases, oxidizing agents, and reducing agents. However, in the compound [[toluene]], [[phenyl|C<sub>6</sub>H<sub>5</sub>]]CH<sub>3</sub>, the methyl group is considerably more reactive due to the electron donating abilities of the ring.[[electrophile|Electrophilic]] reagents are then able to attack the methyl group; for example, oxidation with [[permanganate]] converts the methyl group to carboxyl (-COOH), which produces [[benzoic acid]].

==Methyl radical==
The methyl radical is the substance CH<sub>3</sub> on its own, with an unpaired electron. Though it readily dimerizes to [[ethane]], it is stable enough (unlike atomic hydrogen) to be observed as a dilute gas. It can be produced by thermal decomposition of certain compounds, especially those with a -N=N- linkage, which lose the extremely stable dinitrogen molecule on heating.

== See also ==
* [[methanol#History|methanol history]] for the [[etymology]] of ''methyl''
{{clr}}
[[Category:Functional groups]]

[[da:Methyl]]
[[de:Methylgruppe]]
[[es:Metil]]
[[fr:Méthyle]]
[[it:Metile]]
[[nl:Methylgroep]]
[[ja:メチル基]]
[[pl:Grupa metylowa]]
[[pt:Metil]]
[[ru:Метил]]
[[fi:Metyyli]]
[[sv:Metylgrupp]]
[[vi:Nhóm methyl]]
[[zh:甲基]]

{{jb1}}

{{WikiDoc Help Menu}}
{{WikiDoc Sources}}