Benzene

Benzene is an important organic chemical compound with the chemical formula C₆H₆. The benzene molecule is composed of 6 carbon atoms joined in a ring with 1 hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.

Benzene is a natural constituent of crude oil and is one of the elementary petrochemicals. Because of the cyclic continuous pi bond between the carbon atoms, benzene is classed as an aromatic hydrocarbon, the second [n]-annulene ([6]-annulene. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell. It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced. Because benzene has a high octane number, it is an important component of gasoline.

Because benzene is a human carcinogen, most non-industrial applications have been limited.

Contents

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• 1History
  • 1.1Discovery
  • 1.2Ring formula
  • 1.3Nomenclature
  • 1.4Early applications
  • 1.5Occurrence
• 2Structure
• 3Benzene derivatives
• 4Production
  • 4.1Catalytic reforming
  • 4.2Toluene hydrodealkylation
  • 4.3Toluene disproportionation
  • 4.4Steam cracking
  • 4.5Other methods
• 5Uses
  • 5.1Component of gasoline
• 6Reactions
  • 6.1Sulfonation, chlorination, nitration
  • 6.2Hydrogenation
  • 6.3Metal complexes
• 7Health effects
• 8Exposure to benzene
  • 8.1Benzene exposure limits
  • 8.2Toxicology
    • 8.2.1Biomarkers of exposure
    • 8.2.2Biotransformations
    • 8.2.3Molecular toxicology
    • 8.2.4Biological oxidation and carcinogenic activity
  • 8.3Routes of exposure
    • 8.3.1Inhalation
      • 8.3.1.1Exposure through smoking
    • 8.3.2Exposure from soft drinks
    • 8.3.3Harbin, China
• 9See also
• 10References
• 11External links