Principles of Organic Nomenclature

R-1.2.2 Replacement operation

The replacement operation involves the exchange of one group of atom or a single nonhydrogen atom for another. This can be expressed in several ways as follow:

R- By use of "a" prefixes representing the element(s) being introduced, usually signifying replacement of carbon (see R-9.3).

Examples to R-


(replacement prefix = sila)


(replacement prefix = aza)

Note: Except for bismuth, a replacement term for a cationic atom of the nitrogen, chalcogen or halogen families of elements is denoted by replacing the final "a" of the corresponding replacement term for the neutral heteroatom by "-onia"; the cationic replacement term for bismuth, the "a" term for which is "bisma", is "bismuthonia" (see R-5.8.2).

R- By use prefixes or infixes signifying replacement of oxygen atoms or oxygen-containing group (see R-3.4). These affixes represent the group(s) being introduced.

Examples to R-

Methyl dimethylphosphinate
Methyl P,P-dimethylphosphinimidate
(replacement infix = imid(o))
Phenylphosphonic acid
Phenylphosphononitridic acid
(replacement infix = nitrid(o))
The chalcogen affixes "thio-", "seleno-", and "telluro-" indicate replacement of an oxygen atom by another chalcogen atom.

Examples to R-

Benzoic acid

Selenobenzoic acid



Hexanoic acid

Hexane(dithioic) acid

4-Formylbenzoic acid

4-(Selenoformyl)benzoic acid
R-1.2.3 Additive operation
R-1.2.4 Conjunctive operation
R-1.2.5 Subtractive operation
R-1.2.6 Ring formation or cleavage
R-1.2.7 Rearrangement
R-1.2.8 Multiplicative operation

This HTML reproduction is as close as possible to the published version [see IUPAC, Commission on Nomenclature of Organic Chemistry. A Guide to IUPAC Nomenclature of Organic Compounds (Recommendations 1993), 1993, Blackwell Scientific publications, Copyright 1993 IUPAC]. If you need to cite these rules please quote this reference as their source.

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