Metil

Metil, frequently rendered as methyl in English, denotes the methyl functional group in organic chemistry. It is a substituent with the formula -CH3 when attached to a parent molecule, or the moiety CH3 in molecular fragments. The methyl group is small, nonpolar, and hydrophobic, and it commonly increases the lipophilicity of compounds.

In chemistry, the methyl group appears in a wide range of substances, from simple molecules such as methane (CH4) and chloromethane (CH3Cl) to more complex compounds like methyl esters (for example, methyl formate, HCOOCH3) and methylated hydrocarbons such as toluene (methylbenzene). In naming, the substituent is described as methyl- or the suffix -methyl in systematic IUPAC nomenclature, while the root forms meth- in some parent names (as in methane or methanol).

Biologically, methyl groups play essential roles in epigenetics and metabolism. DNA methylation, typically at cytosine residues in CpG dinucleotides, is a key mechanism for regulating gene expression, development, and genomic imprinting. Methyl groups are transferred by methyltransferase enzymes using S-adenosyl methionine as a common methyl donor.

Industrial and health considerations vary with the specific methyl compound. Some methyl compounds, such as methanol or methyl halides, can be toxic or hazardous; others are common reagents in synthesis and pharmaceuticals. Overall, the methyl group is one of the most fundamental and widely encountered motifs in chemistry and biochemistry.