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Information on Chemical Nomenclature: Overview

A guide to chemical nomenclature

Information on Chemical Nomenclature

A single compound may have many different names in the chemical literature. For example, the simple compound: H2NCH2CH2OH can be named: 2-Aminoethanol, 2-Aminoethyl alcohol, 2-Hydroxyethylamine, beta-Hydroxyethylamine, 2-Hydroxyethanamine, or 1-Amino-2-; and also has the less systematic ("trivial") name Ethanolamine.

Subject Guide

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Judith Currano
1973 Wing, Chemistry Laboratories


The International Union of Pure and Applied Chemistry (IUPAC) grew out of the international recognition of a need for standardization in chemistry. It is the recognized world authority on chemical nomenclature, terminology, symbols, units, atomic weights and related topics.

The IUPAC Home Page provides access to the full text of a number of IUPAC recommendations, including: IUPAC Glossary of Organic Class Names; Nomenclature of Amino Acids and Peptides; Steroid Nomenclature.


IUPAC have published a number of compilations of their rules on nomenclature, including:

Commission on the Nomenclature of Inorganic Chemistry "Red Book" Nomenclature of Inorganic Chemistry, Recommendations 1990, Blackwell Scientific Publications, 1990. Edited by G J Leigh. [Reference: QD 149.N66 1990]

Commission on the Nomenclature of Organic Chemistry "Blue Book" Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, 1979. Edited by J Rigaudy and S P Klesney. [Reference: QD 291.I57 1979]

A Guide to IUPAC Nomenclature of Organic Chemistry, Recommendations 1993, Blackwell Scientific Publications, 1993. Edited by R Panico, W H Powell and J C Richer. [Reference: QD 291.I57 1993]

Revisions or additions to the IUPAC recommendations appear in the journal Pure and Applied Chemistry. A list of these is available here

You can access the full text of many of the IUPAC recommendations from their old Web site, at


As a chemist you will have a working knowledge of chemical nomenclature, but only a few experts will be so familiar with IUPAC rules that they are able to name (almost) any compound. It is nice to be able to draw the structure into a program and have the program name it for you.

Autonom was a windows-based program which generated IUPAC names from graphic structures. It worked from a library of about 7,000 entries, with an additional index of functional groups, claiming to have an 85% success rate in naming structures and giving a warning if a structure could not be named. Templates helped to simplify the drawing process. Autonom was very popular during the late 1990s and the early 2000s. It was packaged with Beilstein CrossFire, as well as contemporary versions of ChemDraw. However, the program is currently unavailable at the University of Pennsylvania, and its overall status is unknown.

Chemical Abstracts

The nomenclature used by CA has developed in parallel and generally in accordance with IUPAC rules. A major revision of CA index names was carried out in 1972, when most trivial names were dropped. The CA index names for most chemical substances have continued unchanged since that date. In the Chemical Substances Index, compounds are listed alphabetically by name. Ordering is based on the parent compound name, e.g. butane, plus a suffix to denote the principal function, e.g. sulfonic acid, and a locant e.g. 1-. Following a comma, the substituents are listed. e.g. 1-Butanesulfonic acid, 2,4-diamino-3-chloro-ethyl ester. A detailed explanation of names used in CA may be found in the Index Guide, Appendix IV Chemical Substance Index Names. The easiest way, currently, to locate a Chemical Abstracts index name is to search by structure on SciFinder. The first name given in the structure's record will be the index name. If a substance is novel, one can contact the experts at Chemical Abstracts Service (, and request that it be named, for a fee.

CA Index Guide

The Index Guide to Chemical Abstracts is a useful tool for finding CA names for compounds when you know a common or trade name. For example: DDT See Benzene,1,1'-(2,2,2-trichloroethylidene)bis[4-chloro- [50-29-3]

It also indexes Enzyme Commission designations, for example:
E.C. See Insulinase [9013-83-6]

Note: The numbers in square brackets are the CA Registry Numbers for these compounds. Registry Numbers uniquely identify a chemical substance, and should always be used in preference to names when searching computer databases such as SciFinder.

In 2010, Chemical Abstracts Service ceased publication of all printed works, including the Index Guide. The Chemistry Library owns the last available edition of the Index Guide, and it is housed in the library reading room. However, please note that it has not been updated in some years, and newer substances may not appear there.

Ring Systems Handbook

The CA Ring Systems Handbook is very useful for finding CA names of any compounds containing rings. It consists of a catalog of over 91,000 structural diagrams, called the Ring Systems File. The entries are arranged firstly in order of the number of component rings, e.g. "3 RINGS" followed by the sizes of the component rings in ascending order, e.g. "5,6,7", followed by the elemental content of the rings, e.g. "C3N2-C6-C5NO". Substituents are not included in the handbook: it names the 'parent' compound. The RSH also contains an alphabetical listing of names, the Ring Name Index, which can be used to find the structure of any ring-containing parent compound listed in CA. The most recent edition of the RSH that the Chemistry Library owns is from 2003, and the last update supplement is from 2006. The RSH ceased publication in 2010, along with the rest of the Chemical Abstracts Service print resources. Currently, the only way to make use of the ring skeletons is to perform a screened search in the CAS REGISTRY on STN.

Reference Books

Gardner's chemical synonyms and trade names. 10th ed., rev. and enl.
Aldershot, Hants, England ; Brookfield, Vt. : Gower, c1994. [Reserve: TP9 .G286 1994]
Includes more than 40,000 chemicals, listed by common or trade name. Where possible, the CAS registry number, chemical formula, applications and manufacturers are listed.

Howard, Philip H. and Neal, M. Dictionary of chemical names and synonyms
Boca Raton : Lewis Publishers, 1992. [Reserve: TP9 .H65 1992]
Lists approximately 20,000 chemicals, in order of CAS Registry number. Each entry gives the preferred name, synonyms, molecular formula and molecular weight. There are indexes to synonyms and formulas.

GABCOM & GABMET : acronyms of compounds and methods in chemistry and physics / prepared and issued by Gmelin-Institut fur Anorganische Chemie der Max-Planck-Gesellschaft zur Forderung der Wissenschaften.
Berlin ; New York : Springer-Verlag, 1993. [Reserve: QD7 .G33 1993]
A quick reference to abbreviations and acronyms for chemical compounds. Lists the molecular formula, systematic and trivial names of the compound

Marler, E.E.J. Pharmacological and Chemical Synonyms. 8th ed.
Amsterdam: Elsevier, 1985 [Reserve: RS 51.M3 1985]
Index to names of drugs, pesticides and other substances of pharmacological or biochemical interest.

Names, Synonyms and Structures of Organic Compounds
Boca Raton: CRC Press, 1995
Compounds are listed by Registry Number. Gives structure drawing, systematic name, synonyms, and molecular formula. There are indexes to names and formulas.

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