AskDefine | Define methyl

Dictionary Definition

methyl n : the univalent radical CH3- derived from methane [syn: methyl group, methyl radical]

User Contributed Dictionary

English

Pronunciation

  • /"mET.@l/

Noun

  1. The univalent hydrocarbon radical, CH3, formally derived from methane by the loss of a proton.
univalent hydrocarbon radical, CH3
  • Greek: μεθύλιο
  • Italian: metile, metilico qualifier attributive

Extensive Definition

In chemistry, a methyl group is a hydrophobic alkyl functional group named after methane (4). It has the formula -3 and is often abbreviated -Me. Such hydrocarbon groups occur in many organic compounds.
Methyl groups can be incorporated into organic compounds by an SN2 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 substituents into a compound usually increases its lipophilicity and reduces its solubility in water. It should ease its absorption into biological membranes and make its release into aqueous surroundings more difficult. Incorporating a methyl group into a molecule can have any of three effects, each increasing its reactivity (the rate of its metabolism):
  1. by oxidizing the methyl group,
  2. by demethylation (the transfer of the methyl group to another compound), or
  3. by reduction, reducing the analogue.
The reactivity of a methyl group depends on what it is attached to. When occurring in an alkane, it is quite unreactive and resists all but the strongest of acids, bases, oxidizing agents, and reducing agents. But in toluene, C6H5CH3, the methyl group is considerably more reactive, due to the electron donating propensity 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), to produce 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

methyl in Czech: Methyl
methyl in Danish: Methyl
methyl in German: Methylgruppe
methyl in Spanish: Metil
methyl in French: Méthyle
methyl in Italian: Metile
methyl in Dutch: Methylgroep
methyl in Japanese: メチル基
methyl in Occitan (post 1500): Metil
methyl in Polish: Grupa metylowa
methyl in Portuguese: Metil
methyl in Russian: Метил
methyl in Finnish: Metyyli
methyl in Swedish: Metylgrupp
methyl in Vietnamese: Nhóm methyl
methyl in Chinese: 甲基
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