Methyl group

A methyl group in organic chemistry is an alkyl group derived from methane, consisting of one carbon atom bonded to three hydrogen atoms (CH3). It is highly stable but can exist in reactive forms: methylium cation (CH+3), methanide anion (CH−3), and methyl radical (CH•3). These forms are rare and reactive, with the cation detected in interstellar space. The reactivity of a methyl group depends on its environment; it is generally unreactive but can undergo oxidation to hydroxymethyl (−CH2OH), formyl (−CHO), or carboxyl (−COOH) groups under specific conditions.

Methylation involves transferring the methyl group using agents like methyl iodide. Deprotonation of a methyl group can form carbanions, and free rotation around the C–C axis is possible in simple cases but restricted in more complex molecules due to steric hindrance or external interactions. Chiral methyl groups, where one hydrogen is replaced by deuterium (D) and another by tritium (T), are used to analyze stereochemical transformations.

The term "methyl" originates from the Greek words for "wine" and "substance," introduced by French chemists in the 19th century. It is a key concept in organic chemistry, describing molecules with a single carbon atom attached to other groups.