Aromatic Hydrocarbons—Benzene and Other Alkylbenzenes

Benzene and its alkyl derivatives are monocyclic aromatic compounds (arenes). The compounds are of considerable economic importance as industrial raw materials, solvents, and components of innumerable commercial and consumer products. The aromatics differ vastly in chemical, physical, and biologic characteristics from the aliphatic and alicyclic hydrocarbons. The aromatics are more toxic to humans and other mammals; of prime importance are (1) the hematopoietic toxicity of benzene resulting in aplastic anemia in humans and other mammalian species, (2) benzene-induced leukemia in humans, and (3) the cerebellar lesions and loss of central nervous system (CNS) integrative functions in “glue sniffers” exposed to high levels of toluene. The simplest single-ring aromatic hydrocarbon compound is benzene, the nonsubstituted ring system. When one methyl group is attached to the ring, toluene is formed, and with two attached methyl groups, xylene is formed. Xylene occurs in three isomeric forms. The hemimellitines and mesitylenes possess three methyl groups, durene four, and the penta- and hexamethylbenzenes, five and six methyl groups, respectively. Other industrially important compounds are ethylbenzene and isopropylbenzene or cumene. Keywords: Aromatic hydrocarbons; benzene; alkylbenzenes; Environmental impact