ACD/Name

Substitutive Nomenclature

Rule C-12 Guide to Construction of the Name

After the principal group(s) have been chosen and named, the parent compound is next chosen by one of the following methods. For details of numbering, see Subsection C-0.15 and for the arrangement of prefixes see Subsection C-0.16.

12.1 - If the compound is purely acyclic, the principal chain is chosen as parent for nomenclature by the methods given in Subsection C-0.13 and is named according to the Rules 1.1, 3.1, 3.2, and 3.3 of Section A.

Example to Rule C-12.1

Principal group: -one
Principal chain: Hexane
Principal chain including principal group: 2-Hexanone
Subtractive modification: 3-Hexen-2-one
Prefixes: Chloro-
Hydroxy-
Methyl-
Together with later rules this leads to the name:
3-Chloro-6-hydroxy-5-methyl-3-hexen-2-one

12.2 - If the principal group occurs only in a chain which carries a cyclic substituent, the compound is named as an aliphatic compound into which the cyclic component is substituted, by means of a radical prefix. It is not necessary that the chain bearing the cyclic substituent shall be the longest chain.

Example to Rule C-12.2

Principal group: -oic acid
Principal chain: Hexane
Principal chain including principal group: Hexanoic acid
Subtractive modification: 3-Hexenoic acid
Prefixes: Chloro-
Cyclohexyl-
Hydroxy-
Methyl-
Together with later rules this leads to the name:
3-Chloro-5-cyclohexyl-6-hydroxy-5-methyl-3-hexenoic acid

12.3 - If the principal group occurs in two or more carbon chains that are not attached directly to one another (that is, do not together form a branched chain but are separated by, for instance, a ring or hetero atom), then that chain is chosen as parent for nomenclature which carries the largest number of the principal group; if the numbers of these groups in two or more chains are the same, choice is made by the principles for selection of the principal chain (see Subsection C-0.13); if this does not effect a choice, the compound is named as an assembly of identical units (see Subsection C-0.7).

Example to Rule C-12.3

Principal group: -ol
Principal chain, i.e., that carrying two OH: Ethanediol
Prefix: p-(3-Hydroxypropyl)phenyl
Together with later rules this leads to the name:
1-[p-(3-Hydroxypropyl)phenyl]-1,2-ethanediol

12.4 - If the principal group occurs only in one cyclic system, that system forms the parent for nomenclature and is named according to the rules of Sections A and B.

Example to Rule C-12.4

Principal group: -ol
Parent: Cyclohexane
Prefix: Ethyl-
Together with later rules this leads to the name:
2-Ethyl-1-cyclohexanol

12.5 - If the principal group occurs in more than one cyclic system, that system is chosen as parent for nomenclature which carries the largest number of the principal group; if the numbers in two or more systems are the same, the senior ring system is chosen as parent according to the rules for seniority of ring systems in Subsection C-0.14; if these rules do not effect a choice, the substance is named as an assembly of identical units (see Subsection C-0.7).

Examples to Rule C-12.5

Principal group: -carboxylic acid
Senior ring system for parent: Fluorene
Name of parent including principal group: Fluorene-2-carboxylic acid
Prefixes: Phenyl-
Carboxy-
Together with later rules this leads to the name:
6-(p-Carboxyphenyl)fluorene-2-carboxylic acid

12.6 - If the principal group occurs both in a chain and in a cyclic system, the parent for nomenclature is that portion in which the principal group occurs in largest number; if the numbers are the same in two or more portions, that portion is chosen as parent for nomenclature which is considered to be the most important (for general considerations see Rule A-61) or is the senior (see Subsection C-0.14).

Examples to Rule C-12.6

Principal group: -ol
Component carrying largest
number of principal groups:
Name of parent including suffix: Pentanediol
Substituent to be named as prefix: 4-Hydroxycyclohexyl
Together with later rules this leads to the name:
1-(4-Hydroxycyclohexyl)-1,5-pentanediol
Principal group: -one
Component carrying largest
number of principal groups:
1,2-Cyclopentanedione
Substituent to be named as prefix: 2-Oxobutyl
Together with later rules this leads to the name:
4-(2-Oxobutyl)-1,2-cyclopentanedione
Principal group: -al
Parent (Rule A-61.4): chain Nonane
Parent including suffix: Nonanal
Substituent to be named as prefix: 4-Formylcyclohexyl
Together with later rules this leads to the name:
9-(4-Formylcyclohexyl)nonanal

12.7 - When a substituent is itself substituted, all the subsidiary substituents are named as prefixes. The substituent bearing the subsidiary substituents is regarded as a "parent radical" (analogous to a parent compound). The nomenclature of the whole substituent is subject to all the procedures adopted for compounds (for example, choice of principal chain) with two exemptions, namely (a) that no suffix is used and (b) that the point of attachment of the radial bears the lowest permissible number which for a chain must be 1 (see Rules A-1.2, A-2.25, and A-3.5).

Example to Rule C-12.7

Principal group: -carboxylic acid
Parent (Rule C-12.4) Cyclohexane
Substituent to be named as prefix:
Parent substituent chain: Hexyl-
Subsidiary prefixes: Chloro-
Oxo-
name composed of:
Methyl-
Hydroxy-
giving Hydroxymethyl-
Other substituent in cyclohexane ring: Chloro-
Together with later rules this gives the name:
4,5-Dichloro-2-[4-chloro-2-(hydroxymethyl)-5-oxohexyl]-1-cyclohexanecarboxylic acid

See Recommendations'93 R-4

Next:
Guide to Construction of the Name
Rule C-12.8
Rule C-12.9

search


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., www.acdlabs.com, +1(416)368-3435 tel, +1(416)368-5596 fax. For comments or suggestions please contact webmaster@acdlabs.com