Abstract

Benzene, C₆H₆, is a volatile, colorless, and flammable liquid aromatic hydrocarbon possessing a distinct, characteristic odor. Benzene is used as a chemical intermediate for the production of many important industrial compounds, such as styrene (polystyrene and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline (dyes), alkylbenzenes (detergents), and chlorobenzenes. These intermediates, in turn, supply numerous sectors of the chemical industry producing pharmaceuticals, specialty chemicals, plastics, resins, dyes, and pesticides. Benzene has also found limited application in medicine for the treatment of certain blood disorders, such as polycythemia and malignant lymphoma, and in veterinary medicine as a disinfectant. Benzene, along with other light high octane aromatic hydrocarbons such as toluene and xylene, is used as a component of motor gasoline. Benzene is no longer used in appreciable quantity as a solvent because of the health hazards associated with it. Since the 1950s, benzene production from petroleum feedstocks has been very successful and accounts for ~ 95% of all benzene obtained. Benzene is the simplest and most important member of the aromatic hydrocarbons. Petroleum-derived benzene is commercially produced by reforming and separation, thermal or catalytic dealkylation of toluene, and disproportionation. Benzene is also obtained from pyrolysis gasoline formed in the steam cracking of olefins. World capacity was 40 × 10⁶t as of Jan. 2000. Several different grades of benzene are commercially available. Benzene is classified as a flammable liquid and should be stored away from any potential source of ignition. Benzene is shipped by rail tank cars, trucks, barges, and tankers. Because of the flammability, toxicity, and volatility of benzene, transfers from one vessel to another are conducted in closed systems. Benzene should be handled only where adequate ventilation is provided; protective clothing and self-contained respirators are recommended. Benzene is classified as a hazardous waste. Benzene emissions and effluent streams from petroleum refineries or benzene processing plants are also subject to strict federal regulations.