Identification

• Benzene is an organic compound made of hydrogen and carbon. It is colorless, has a distinctly sweet odor, and is very flammable.
  
  

Warning

• Benzene is a known carcinogen. Breathing benzene vapors in low levels can cause drowsiness, dizziness, elevated heart rate, headaches, tremors, and eventually unconsciousness. Breathing it in concentrated levels is lethal. Substantial benzene exposure damages the bone marrow, causing anemia, and in severe cases immune system damage or leukemia.
  
  

Function

• Benzene is a major industrial solvent, a precursor substance for the manufacture of plastics, synthetic rubber, certain dyes, certain types of glue, and some drugs. It is still sometimes used as an anti-knock additive in gasoline, although this has been generally discontinued because of the dangers of vaporized benzene. Before it was discovered to be carcinogenic, benzene was used to add scent to aftershave and decaffeinate coffee.
  
  

Considerations

• Although trace amounts of benzene come into being whenever a carbon-rich substance is partly burned (cigarette tobacco or forest fires, for example), most industrial benzene is made through a process called catalytic reforming. This mixes hydrocarbons with hydrogen gas at high temperature, producing compounds called aromatic hydrocarbons. These compounds include benzene, which is then distilled out of the mixture.
  
  

History

• Michael Faraday first isolated and discovered benzene in 1825. He observed the substance in the oily residue left over from the production of illuminating gas, and gave it the name "bicarburet of hydrogen." Further discoveries related to benzene and other aromatic hydrocarbons continued through the 19th Century.