ACD/Name

Specific Classes of Compounds

R-5.7.5 Lactones, lactams, lactims, and analogues

Compounds that may be considered as derived from a hydroxy catboxylic acid or amino carboxylic acid by loss of water intramolecularly are called generically "lactones" or "lactams", respectively. Tautomeric forms of lactams are called "lactims". In these recommendations, such compounds are preferably named as heterocycles although names that may be considered to be derived from the corresponding hydroxy or amino acid are also given.

R-5.7.5.1 Lactones. Inrtamolecular esters of hydroxy carboxylic acids are "lactones" and are named as heterocycles or by substituting "-olactone" for the "-ic acid" ending of a trivial name of a hydroxy acid, or "-lactone" for the "-ic acid" ending of a systematic "-oic acid" name for the nonhydroxylated parent acid, and inserting a locant designating the position of the hydroxy group between the "o" and "lactone"

Example to R-5.7.5.1

Heterocycles in which one or more (but not all) rings of a polycyclic ring system are lactones are named bu adding the suffix "-carbolactone" (denoting a cyclic group) to the name of the ring system left after the residue is replaced by two hydrogen atoms, preceded by a pair of locants indicating the points of attachment of the carbonyl group and the oxygen atom of the lactone, respectively; the locant for the carbonyl group is cited first, and, if there is a choice, is the lower locant. Multiplying prefixes and pairs of locants separated by a colon denote the precence of two or more lactone rings.

Examples to R-5.7.5.1

(R-2.4.2.1)

(R-2.4.4.1)

R-5.7.5.2 Sultones. Intramolecular esters of hydroxy sulfonic acids are called "sultones" and are named as heterocycles or by citing the term "sultone" denoting the cyclic group after the name of the appropriate parent hydride preceded by a pair of locants describing the points of attachment of the sulfonyl group and oxygen atom, respectively; the locant for the sulfonyl group is cited first and, if there is a choice, is the lower locant. Multiplying prefixes and pairs of locants separated by a colon are used to indicate two or more sultone rings.

Examples to R-5.7.5.2

R-5.7.5.3 Lactams and lactims. Nitrogen analogues of lactones having the group as part of a ring or ring system are called generically "lactams" and their tautomers, , are "lactims". These compounds are named as heterocyclic compounds or in accordance with R-5.7.5.1 using "-lactam" or "-lactim", respectively, in place of "-lactone".

Names such as "propiolactam" and "butyrolactim" are not included in these recommendations.

Examples to R-5.7.5.3

Tetrahydropyrrol-2-one

Pyrrolidin-2-one (2-Pyrrolidone)

Butano-4-lactam

R-5.7.5.4 Sultams. Nitrogen analogues of sultones having the group as a part of a ring are named as heterocycles or in accordance with R-5.7.5.2 using "sultam" in place of "sultone". The locant for the point of attachment of the sulfonyl group is cited first and, where there is a choice, has preference over the imino group for lower locant.

Examples to R-5.7.5.4

Next:
R-5.7.6 Acid halides
R-5.7.7 Anhydrides and their analogues
R-5.7.8 Amides, imides, and hydrazides
R-5.7.9 Nitriles, isocyanides and related compounds

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This HTML reproduction is as close as possible to the published version [see IUPAC, Commission on Nomenclature of Organic Chemistry. A Guide to IUPAC Nomenclature of Organic Compounds (Recommendations 1993), 1993, Blackwell Scientific publications, Copyright 1993 IUPAC]. If you need to cite these rules please quote this reference as their source.

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