1methylethenyl

1-methylethenyl is a hydrocarbon substituent in organic chemistry. It is the systematic IUPAC name for the isopropenyl group, a vinyl-substituted methyl fragment that is derived from propene by forming a bonding site with a parent molecule. The group has the chemical formula C3H5 and is encountered in a variety of compounds as a reactive vinyl-type substituent.

In terms of structure, the isopropenyl group is commonly described as a vinyl-substituted methyl unit. Depending on the drawing convention, it can be represented in different orientations, but it essentially consists of a vinyl moiety (a carbon–carbon double bond) bearing a methyl substituent. As a result, the group is used to connect to a parent structure at a vinylic carbon, enabling a range of reactivity typical of vinyl groups.

Applications and occurrence: The 1-methylethenyl substituent appears in numerous organic molecules, including isopropenyl derivatives of aromatic and aliphatic frameworks. It is a versatile building block in synthesis, contributing to pathways in polymer chemistry, fragrance chemistry, and material science. Compounds bearing this substituent can participate in polymerization and various addition reactions characteristic of vinyl groups.

Synonyms and naming: The substituent is widely known as isopropenyl. Its systematic name, 1-methylethenyl, reflects its origin from propene (propene-derived vinyl with a methyl substitution). In the literature, both names may be encountered, with 1-methylethenyl used in formal IUPAC contexts and isopropenyl appearing in common usage.

See also: Ethenyl (vinyl) group, vinylidene substituents, isopropyl and related alkenyl substituents.