Nomenclature of Sulfenic, Sulfinic and Sulfonic Acids

Written by J.A Dobado | Last Updated on April 22, 2024

What are sulfenic, sulfinic and sulfonic acids?

Sulfenic, sulfinic, and sulfonic acids are all types of sulfur-containing acids that are characterized by the presence of a sulfur atom bonded to oxygen atoms. These acids are named according to the number and type of oxygen atoms that are bonded to the sulfur atom.

Sulfenic acids are characterized by the presence of one sulfur-oxygen double bond (S=O), which is represented by the formula R-S(=O)OH. The R group is a substituent that can be a variety of different functional groups, such as an alkyl group or an aryl group.

Sulfinic acids, on the other hand, are characterized by the presence of one sulfur-oxygen single bond (SO), which is represented by the formula R-SO(OH)2. The R group can again be a variety of different functional groups.

Sulfonic acids, also known as sulfuric acid derivatives, are characterized by the presence of a sulfur atom bonded to two or more oxygen atoms through single bonds (SO). These compounds are represented by the formula R-SO3H, where the R group can be a variety of different functional groups.

Sulfenic  and sulfinic acids are also unstable compounds that are difficult to isolate and are usually only observed as intermediates in chemical reactionsSulfonic acids are more stable than sulfenic and sulfinic acids and can be isolated and studied in their own right.

What are nomenclature of sulfenic, sulfinic and sulfonic acids?

Oxyacids derived from sulfur directly attached to an organic radical are named with the name of the hydrocarbon with the same number of carbons, ending in –sulfenic, –sulfinic and –sulfonic, respectively (IUPAC recommendation C-641.1).

When acting as substituents, the suffixessulfene, –sulfino and –sulfo, respectively, are used (IUPAC recommendation C-641.2).

2-pentanesulfenic acid - iupac nomenclature - molecule svg sketch
2-Pentanesulfenic acid
benzenesulfinic acid - iupac nomenclature - molecule svg sketch
Benzenesulfinic acid
4-methylbenzenesulfonic acid - iupac nomenclature - molecule svg sketch
4-Methylbenzenesulfonic acid

Some common names such as sulfanilic acid, naphthionic acid and taurine have been retained.

sulfanilic acid - iupac nomenclature - molecule svg sketch
Sulfanilic acid
naphthionic acid - iupac nomenclature - molecule svg sketch
Naphthionic acid
taurine - iupac nomenclature - molecule svg sketch
Taurine

Other examples

The sulfenic acid derived from ethanol is named “ethanethiolsulfenic acid.” Sulfinic acids are usually named by adding the suffix “-sulfinic acid” to the name of the parent compound.

For example, the sulfinic acid derived from ethanol is named “ethanethiolsulfinic acid.”

Sulfonic acids are usually named by adding the suffix “-sulfonic acid” to the name of the parent compound. For example, the sulfonic acid derived from ethanol is named “ethanethiolsulfonic acid.”

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