2 Substituted Systems
2.1
Preliminary General Remarks
The notion of a "substituent", which has already been repeatedly used in
the discussions of substituent groups derived from parent structures, will
obviously occupy a central position in the following sections and therefore
requires a broadened definition.
The designation "substituent" pertains to any atom and any combination of atoms (functional group) that replaces a hydrogen atom of a
parent structure.
A broader specification of the notion "substituent" is obtained by subsuming all substituting groups other than hydrocarbon or hetero-cyclic/catenic groups under the term characteristic group. These groups then
determine the (functional) class; a class name must not necessarily reappear in the name of the individual members of the compound class in
question, e.g.: -COOH carboxylic acid, -N02 nitro compound, -NH2
amine or amino compound, -OH alcohol, etc. The trivial fact that a parent
structure can simultaneously be substituted by several characteristic
groups necessitates a seniority order for substituents. The most senior
group then always defines the nominal compound class and is, whenever
possible, expressed as a suffix to the parent name; other characteristic/functional groups present are abstracted in the form of appropriate
prefixes, in alphabetical order and in compliance with the principle of
lowest locants.
Multiplying prefixes are used in the same way as with parent structures: the series di, tri, tetra ... for sets of identical substituents, the series
bis, tris, tetrakis ... for identically substituted identical substituents (or if
linguistically better suited), and the series bi, ter, quater ... for identical
partial components directly joined together.
While the nomenclature procedures for parent structures have been
comprehensively unified, for substituted systems the situation is much
less comfortable since 1) differing nomenclature systems are still used
2.1
Preliminary General Remarks
The notion of a "substituent", which has already been repeatedly used in
the discussions of substituent groups derived from parent structures, will
obviously occupy a central position in the following sections and therefore
requires a broadened definition.
The designation "substituent" pertains to any atom and any combination of atoms (functional group) that replaces a hydrogen atom of a
parent structure.
A broader specification of the notion "substituent" is obtained by subsuming all substituting groups other than hydrocarbon or hetero-cyclic/catenic groups under the term characteristic group. These groups then
determine the (functional) class; a class name must not necessarily reappear in the name of the individual members of the compound class in
question, e.g.: -COOH carboxylic acid, -N02 nitro compound, -NH2
amine or amino compound, -OH alcohol, etc. The trivial fact that a parent
structure can simultaneously be substituted by several characteristic
groups necessitates a seniority order for substituents. The most senior
group then always defines the nominal compound class and is, whenever
possible, expressed as a suffix to the parent name; other characteristic/functional groups present are abstracted in the form of appropriate
prefixes, in alphabetical order and in compliance with the principle of
lowest locants.
Multiplying prefixes are used in the same way as with parent structures: the series di, tri, tetra ... for sets of identical substituents, the series
bis, tris, tetrakis ... for identically substituted identical substituents (or if
linguistically better suited), and the series bi, ter, quater ... for identical
partial components directly joined together.
While the nomenclature procedures for parent structures have been
comprehensively unified, for substituted systems the situation is much
less comfortable since 1) differing nomenclature systems are still used