29.1.4—Systematic nomenclature of simple aromatic

For one benzene ring with simple substituents, name the ring parent and assign numbers that give the set of substituent locants the lowest possible value; list prefixes alphabetically when required.

The principal functional group can determine the parent name, such as benzoic acid or phenol. Start numbering at that group, then choose the direction that minimises the remaining locants.

A nitro group opposite the carboxylic acid is 4-nitrobenzoic acid. Three bromines on phenol at the 2, 4 and 6 positions give 2,4,6-tribromophenol.

Do not number a substituted benzene as if it were a straight chain, and do not choose the direction that merely gives the first substituent a small number while making the full locant set larger.