Disubstituted

Disubstituted is a term used in chemistry to describe a molecule that carries two substituent groups attached to a common parent structure. The two substituents may be the same or different, and their relative arrangement often defines distinct isomers with different properties.

In aromatic chemistry, disubstituted rings are common. On a benzene ring the relative positions of the two substituents are described as ortho (1,2-), meta (1,3-), or para (1,4-). Examples include 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,4-dichlorobenzene. Similar nomenclature applies to other aromatic systems and can extend to more complex polycyclic rings.

Disubstitution also applies to alkanes, cycloalkanes, and alkenes. For alkenes, the presence of two substituents on a double bond can give rise to E/Z (cis/trans) stereoisomerism. In cycloalkanes, a 1,2-disubstituted ring can exist as cis or trans, influencing conformation and physical properties. In acyclic alkanes, two substituents around a central framework can affect reactivity, steric hindrance, and polarity.

Naming conventions typically use locants to indicate where the substituents are attached (for example, 1,2- or 1,4-), and prefixes such as di-, bis-, or two are used when substituents are the same or different. Disubstituted compounds are common in synthetic chemistry and materials science, where substitution patterns guide reactivity, directing effects, and physical properties.