Bring the power of IUPAC naming to your desktop!

ACD/Name (Chemist Version) offers a standardized set of features for quick and simple generation of IUPAC names, and structures from names. It is a streamlined version of our popular ACD/Name software.

View a full description and pricing on our web store.

Carboxylic Acids and their Derivatives

Acid Anhydrides Rule C-491

491.1 - Symmetrical anhydrides of monocarboxylic acids, when unsubstituted, are named by replacing the word "acid" by "anhydride".

Examples to Rule C-491.1

Note: In some languages the word "acid" is included before "anhydride".

491.2 - Anhydrides of substituted monocarboxylic acids, if symmetrically substituted, are named by prefixing "bis-'' to the name of the acid and replacing the word "acid" by "anhydride''. The "bis'' may, however, be omitted.

Examples to Rule C-491.2

491.3 - Mixed anhydrides (anhydrides of different monobasic acids) are named by giving in alphabetical order the first (i.e., the specific) part of the names of the two acids, followed by "anhydride''.

Examples to Rule C-491.3

491.4 - Cyclic anhydrides of polycarboxylic acids, although possessing a heterocyclic structure, are preferably named as acid anhydrides, as in Rule C-491.1 but with any necessary locants.

Examples to Rule C-491.4

See Recommendations'93 R-5.7.7

This HTML reproduction of Sections A, B and C of IUPAC "Blue Book" is as close as possible to the published version [see Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, Oxford, 1979. Copyright 1979 IUPAC.] If you need to cite these rules please quote this reference as their source.

Published with permission of the IUPAC by Advanced Chemistry Development, Inc.,, +1(416)368-3435 tel, +1(416)368-5596 fax. For comments or suggestions please contact