2octyl

2-octyl is a chemical substituent designation used in organic chemistry to indicate an octyl group connected to a parent molecule at the second carbon of the octyl chain. The term is one of several possible octyl substituents, and its exact structure depends on the parent framework and the specific octyl isomer involved. In systematic IUPAC naming, substituents are described by indicating the point of attachment with a locant; thus a fragment labeled "2-octyl-" would refer to an octyl group attached via its C2 atom to the rest of the molecule. Because octyl chains can be arranged in multiple ways, "2-octyl" does not uniquely specify the full carbon skeleton without additional context; common octyl variants used in naming include n-octyl and other branched forms, and the precise isomer is defined by the broader name or structural diagram.

2-octyl groups occur in a variety of compound classes, including alkylated aromatics such as substituted phenols or benzoates, as well as aliphatic esters and ethers. The presence and position of an octyl group influence properties such as hydrophobicity, steric profile, and boiling point, which in turn affect reactivity and material performance.

In practice, chemists specify the full structure alongside the 2-octyl designation to remove ambiguity. See also octyl, n-octyl, isooctyl, and 2-ethylhexyl.