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Substitutive Nomenclature

Seniority of Chains Rule C-13.1

13.11 - In an acyclic compound, that chain upon which the nomenclature and numbering are based is called the "principal chain". When in an acyclic compound there is a choice for principal chain, the following criteria are applied successively, in the order listed, until a decision is reached:

(a) Maximum number of substituents corresponding to the principal group.

Example to Rule C-13.11(a)

(b) Maximum number of double and triple bonds considered together.

Example to Rule C-13.11(b)

(c) Maximum length.

Example to Rule C-13.11(c)

(d) Maximum number of double bonds.

Example to Rule C-13.11(d)

(e) Lowest locants for the principal groups (that is, for the suffix).

Example to Rule C-13.11(e)

(f) Lowest locants for multiple bonds.

Example to Rule C-13.11(f)

(g) Lowest locants for double bonds.

Example to Rule C-13.11(g)

(h) Maximum number of substituents cited as prefixes.

Example to Rule C-13.11(h)

(i) Lowest locants for all substituents in the principal chain cites as prefixes.

Example to Rule C-13.11(i)

(j) The substituent first cited in alphabetical order.

Example to Rule C-13.11(j)

(k) Lowest locants for the substituent cited first as prefix in alphabetical order (see Subsection C-0.16).

Example to Rule C-13.11(k)

Seniority of Chains
Rule C-13.2
Rule C-13.3


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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