Nomenclature of Phenols

Phenols are the organic compounds containing a benzene ring bonded to a hydroxyl group. They are also known as carbolic acids. Thus, a phenol molecule consists of two parts one aryl group part and the other hydroxyl group part.

On the basis of the number of hydroxyl groups attached to the aryl group, it can be classified into mono-, di-, tri- or polyhydric phenols.

Nomenclature of Phenols

Earlier, most of the compounds with the same structural formula were known by different names depending on the regions where they were synthesized. This naming system was very trivial since it raised a lot of confusion. Finally, a common naming system enlisting standard rules was set up by IUPAC for the naming of compounds.

It is both a common name and an IUPAC name for the compounds containing a benzene ring attached to a hydroxyl group. Structurally phenols are the simplest hydroxy derivative of the benzene ring. IUPAC nomenclature of phenols follows a set of rules.

Also, Read: Phenolic Acid

Rules underlying the Nomenclature of Phenols

1. Locate the position of a hydroxyl group attached to the benzene ring.
2. Benzene rings attached to more than one hydroxyl group are labelled with the Greek numerical prefixes such as di, tri, tetra to denote the number of similar hydroxyl groups attached to the benzene ring. If two hydroxyl groups are attached to the adjacent carbon atoms of the benzene ring, it is named as benzene1,2-diol
3. In the case of substituted phenols, we start locating the positions of the other functional groups with respect to the position where the hydroxyl group is attached. For example, if a methyl group is attached at the fourth carbon atom with respect to the hydroxy group, the compound is named as, 4-Methyl phenol.

1. Depending on the position of substituted functional group with respect to the hydroxyl group, words like ortho (when the functional group is attached to the adjacent carbon atom), para (when the functional group is attached to the third carbon atom from the hydroxyl group), meta (when the functional group is attached to the second carbon atom from the hydroxyl group) are also used for the nomenclature of phenols.

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