methylsubstituted

Methylsubstituted is a chemical descriptor used for molecules in which one or more hydrogen atoms have been replaced by a methyl group, denoted as -CH3. The term applies across various hydrocarbon families, including arenes, cycloalkanes, and alkanes. In IUPAC naming, such substituents are indicated with the prefix methyl- and, when several methyl groups are present, with di-, tri-, and locant numbers to specify their positions (for example, 2,4-dimethylpentane).

Common examples illustrate the concept. Toluene, or methylbenzene, is the simplest methyl-substituted aromatic compound, having a single methyl group on a benzene ring. Xylene refers to dimethylbenzene and exists as three positional isomers: ortho-, meta-, and para-xylene. Methylcyclohexane is a methyl-substituted cyclohexane, and 1,3-dimethylbenzene (m-xylene) is another example within the aromatic family. In alkanes, 2-methylpropane (isobutane) represents a propane skeleton bearing a methyl substituent at the second carbon.

Properties and implications of methyl substitution include changes in hydrophobicity, boiling and melting points, and reactivity. Methyl groups are weakly activating in electrophilic aromatic substitution, directing new substituents to the ortho and para positions on benzene rings. In synthesis and industry, methyl-substituted hydrocarbons serve as solvents, fuels, and building blocks for more complex molecules, and their placement on a molecule can significantly influence physical properties and chemical behavior.