14disubstituiert

14-disubstituted, or 14-disubstituiert in German, is a descriptor used in organic chemistry to indicate that two substituent groups are attached to the carbon numbered 14 in a defined molecular framework. The meaning of 14 depends on the chosen parent structure and its IUPAC numbering; in practice, this label is most often used for rigid polycyclic systems such as steroids, where a single carbon is assigned the number 14 within the ring fusion. The two substituents may be identical (geminal disubstitution) or different, and they may be oriented on the same face or on opposite faces of the ring system, giving rise to stereoisomers such as 14α- and 14β- derivatives.

In systematic naming, the specification 14-disubstituted communicates both the location and the extent of substitution and is often combined with descriptors for stereochemistry and the identities of the substituents (for example 14-methyl, 14-halo, or 14,14-dialkyl). The term is useful for distinguishing isomers that share the same base skeleton but differ in substitution at C14, and it informs synthetic planning and discussions of biological activity.

In applications, 14-disubstituted compounds occur in natural product derivatives and synthetic steroids, where modifications at C14 can influence conformational preferences, receptor interactions, and metabolic stability. Related concepts include other position-specific substitutions such as 1-, 4-, or 8-disubstituted systems and the broader framework of IUPAC nomenclature for substituted hydrocarbons and heterocycles.