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Hydrocarbon Ring Assemblies

Rule A-53. Non-identical Ring Systems

53.1 - Other hydrocarbon ring assemblies are named by selecting one ring system as the base component and considering the other systems as substituents of the base component. Such substituents are arranged in alphabetical order. The base component is assigned unprimed numbers and the substituents are assigned numbers with primes.

53.2 - The base component is chosen by considering the following characteristics in turn until a decision is reached:

(a) The system containing the larger number of rings.

Examples to Rule A-53.2(a)

(b) The system containing the larger ring.

Examples to Rule A-53.2(b)

(c) The system in the lowest state of hydrogenation (see also Part .3 of this rule).

Example to Rule A-53.2(c)

(d) The order of ring systems as set forth in the list of Rule A-21.1.

53.3 - Compounds covered by Part .2(c) of this rule may also be named as hydrogenation products according to Rule A-23

Examples to Rule A-53.3

See Recommendations'93 R-2.4.4

Three or More Identical Ring Systems
Radicals for Identical Ring Systems
Radicals for Non-benzenoid Ring Systems


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.

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