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In chemistry, a 'methyl group' is a hydrophobic alkyl functional group derived from methane (₄). It has the formula -₃ and is very often abbreviated as '-Me' in the structure of a molecule. This hydrocarbon unit can be found in many organic compounds. It is customarily written as H₃C when on the left of a bond; for example, ethane is represented as H₃C-CH₃.
Methyl groups can be incorporated in organic compounds by an S_N2 reaction on iodomethane, or by the reaction of methyl lithium or MeMgCl with a carbon atom that is substituted with a leaving group.

Contents

Reactivity

Methyl radical

See also

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, C₆H₅CH₃, the methyl group is considerably more reactive due to the electron donating abilities of the ring.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 CH₃ 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 for the etymology of ''methyl''