Conjunctive Nomenclature

Rule C-54

54.1 - When different side chains are attached to a cyclic component, (a) that type is chosen for naming by the conjunctive method which contains the principal group, or (b), if there is more than one side chain containing this group, that type which is present in greatest number, or (c), if still no decision has been reached, that which has the requirements for choice as principal chain. (For the last-mentioned criterion it must be remembered that the "side chain" does not extend beyond the cyclic component and most remote principal group.) All other side chains are named as substituents, by prefixes placed before the name of the cyclic component.

Examples to Rule C-54.1

Note: Conjunctive nomenclature is not used when numbering difficulties might arise, as with, for example, unsaturated acids named systematically (names ending in "-enoic", "-dienoic acid", etc.; see Rule C-401). In such cases it would become necessary to denote unsaturation by Greek letters.

54.2 - If there is a choice for cyclic component the senior is chosen (see Subsection C-0.14 on seniority of ring systems).

Examples to Rule C-54.2

See Recommendations'93 R-1.2.4

Conjunctive Nomenclature
Rule C-55
Rule C-56
Rule C-57
Rule C-58

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