carboximide

Carboximide is a term encountered in some chemical literature to refer to a class of compounds in which a carbonyl group derived from a carboxylic acid is directly bonded to a nitrogen atom that bears substituents. In practice, the term is not widely adopted in modern nomenclature and its meaning can vary by context; many authors describe the compound as a carboxamide, an amidine, or an imide depending on the exact connectivity, tautomerism, and functional groups present. The most general motif associated with the idea of a carboximide is the acyl–N bond C(=O)–NR', i.e., a carbonyl carbon attached to nitrogen, as seen in R‑CO‑NR'R''.

In contrast to simple amides (R‑CO‑NR'R'') that have a single acyl group on nitrogen, imides contain two acyl groups on the same nitrogen (or adjacent nitrogens). If the nitrogen bears two acyl attachments, neighboring carbonyls may be present, making the description “imide” more appropriate; if only one acyl on nitrogen with another substituent, “carboxamide” is usually preferred. Thus “carboximide” often appears as a transitional or descriptive label rather than a strict IUPAC name.

Reactivity is typically governed by the amide‑like resonance of the C(=O)–N bond; such species can undergo hydrolysis to carboxylic acids and amines, or act as acylating agents in synthesis. Stability and basicity depend on substituents on nitrogen and the presence of additional carbonyls.

See also: carboxamide, imide, amidine, carboximidic acid.