17.2 : Nomenclature of Aromatic Compounds with a Single Substituent

Benzene is the simplest aromatic hydrocarbon or arene. The IUPAC names for simple monosubstituted benzene derivatives are derived by adding the substituent's name as a prefix to the parent benzene. For example, halobenzene, where the halogen could be fluoro (F), chloro (Cl), bromo (Br), and iodo (I).

The naming of aromatic compounds also depends on the chain length of the alkyl group attached to the benzene ring. If the alkyl chain has six or fewer carbons, the compound is named alkyl-substituted benzene. For example, propylbenzene, where the alkyl group has three carbons.

However, if the alkyl chain has more than six carbons or contains other preferential functional groups, the compound is named a phenyl-substituted derivative. The substituent obtained from benzene is termed phenyl (Ph-), whereas that derived from toluene is benzyl (Bn-) groups. For example, 1-phenylheptane, where the alkyl chain has seven carbons,

1-phenyl-1-pentanone with a ketone functional group,

diphenyl ether, where the key functional group is ether,

and benzyl bromide derived from toluene.

In general, the substituents derived from arenes by loss of hydrogen are called aryls. Some of the simple monosubstituted benzene derivatives have acquired common names accepted by IUPAC nomenclature. For example, vinylbenzene is styrene, and isopropylbenzene is cumene. Benzaldehyde and Benzoic acid are other examples.