isoformyl

Isoformyl is a term encountered in organic chemistry to denote a substituent related to the formyl group (-CHO) in an isomeric sense. The formyl group is the simplest aldehyde functional group and serves as a standard descriptor in many naming schemes. However, isoformyl is not a widely standardized or commonly used name in modern IUPAC nomenclature. Because of its ambiguous and nonuniform usage, the exact structure implied by “isoformyl” can vary between sources.

In practice, isoformyl tends to appear in older literature or in specialized discussions where authors intend to signal an isomeric relationship to a formyl group without specifying a precise connectivity. As a result, names employing isoformyl should be interpreted with caution and supplemented by explicit structural information, such as a diagram or a detailed description of how the formyl-like functionality is attached within the molecule.

Relationship to other terms: isoformyl should not be confused with the standard formyl group, which is a clearly defined aldehyde substituent (-CHO). The prefix iso- in chemistry most often conveys an isomeric relation, but unlike well-defined prefixes for positional isomers (such as ortho-, meta-, para-), isoformyl lacks a single, universally accepted meaning. In modern practice, chemists typically use direct structural descriptors or specific substituent names rather than relying on isoformyl.

See also: formyl group, aldehyde, organic nomenclature, isomer.