Aromatic Hydrocarbons
Aromatic hydrocarbons (also called arenes), despite their name, often (but not necessarily always) have distinctive aromas (odors). In fact, the name is a traditional one, and these organic compounds are characterized by the presence of one or more benzene rings in the molecule. Benzene, and all the larger arenes, has a characteristic planar structure forced on them by the electronic requirements of the six (or more) π electrons. When named as substituents on other structural units, the aromatic units are referred to as aryl substituents.
The aromatic hydrocarbon group contains not only benzene but also derivatives such as toluene (C6H5CH3), the isomeric dimethyl benzene derivatives (CH3C6H4CH3), which are used as solvents, as well as in the synthesis of drugs, dyes, and plastics.
