has role volatile organic compound benzene A six-carbon aromatic annulene in which each carbon atom donates one of its two 2p electrons into a delocalised π system. A toxic, flammable liquid byproduct of coal distillation, it is used as an industrial solvent. Benzene is a carcinogen that also damages bone marrow and the central nervous system. benzenes aromatic annulene non-polar solvent carcinogenic agent environmental contaminant