Skip to Content


« Back to Glossary Index

**History and Discovery of Benzene:**
– Benzene derives from gum benzoin and has been known since ancient times.
– Benzene was first isolated by Michael Faraday in 1825.
– Eilhard Mitscherlich and Charles Blachford Mansfield made significant contributions to benzene’s discovery.
– The term ‘aromatic’ was first applied to benzene by Hofmann in 1855.
– Benzene was detected in deep space in 1997.

**Chemical Structure and Properties of Benzene:**
– Proposed benzene structures by Couper, Loschmidt, and Kekulé.
– Benzene has a boiling point of 80.1°C and specific solubility characteristics.
– It is classified as an aromatic hydrocarbon due to its cyclic pi bonds.
– Benzene’s stability and planar structure contribute to its aromatic properties.
– X-ray diffraction reveals the equal length of all carbon-carbon bonds in benzene.

**Applications and Uses of Benzene:**
– Ludwig Roselius popularized benzene for decaffeinating coffee.
– Benzene was used in various consumer products but its use has been limited due to toxicity.
– Benzene was a by-product of coke production before World War II.
– Post-war, benzene production shifted to petroleum due to increased demand.
– Today, most benzene is sourced from the petrochemical industry.

**Benzene Derivatives and Production Methods:**
– Important compounds like phenol, toluene, and aniline are derived from benzene.
– Biphenyl and fused aromatic hydrocarbons are formed by linking benzene rings.
– Production involves catalytic reforming, toluene hydrodealkylation, and toluene disproportionation.
– Toluene hydrodealkylation and steam cracking are processes used in benzene production.
– Catalytic reformates played a significant role in U.S. benzene production in the late 20th century.

**Toxicity and Health Concerns of Benzene:**
– Benzene is a known carcinogen and volatile organic compound.
– Its toxicity limits its use in consumer items.
– Benzene’s explosive limits and autoignition temperature are important safety considerations.
– Benzene’s presence in petroleum and coal raises health and environmental concerns.
– Understanding the health risks associated with benzene is crucial for its safe handling and use.

Benzene (Wikipedia)

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

Benzene molecule
Space-filling model
Skeletal formula detail of benzene.
Skeletal formula detail of benzene.
Benzene ball-and-stick model
Benzene ball-and-stick model
Ball and stick model
Sample of benzene
Benzene at room temperature
Preferred IUPAC name
Other names
Benzol (historic/German)
Phenylene hydride
Cyclohexa-1,3,5-triene; 1,3,5-Cyclohexatriene (theoretical resonance isomers)
[6]Annulene (not recommended)
Phene (historic)
3D model (JSmol)
ECHA InfoCard 100.000.685 Edit this at Wikidata
EC Number
  • 200-753-7
RTECS number
  • CY1400000
  • InChI=1S/C6H6/c1-2-4-6-5-3-1/h1-6H checkY
  • c1ccccc1
Molar mass 78.114 g·mol−1
Appearance Colorless liquid
Odor sweet aromatic
Density 0.8765(20) g/cm3
Melting point 5.53 °C (41.95 °F; 278.68 K)
Boiling point 80.1 °C (176.2 °F; 353.2 K)
1.53 g/L (0 °C)
1.81 g/L (9 °C)
1.79 g/L (15 °C)
1.84 g/L (30 °C)
2.26 g/L (61 °C)
3.94 g/L (100 °C)
21.7 g/kg (200 °C, 6.5 MPa)
17.8 g/kg (200 °C, 40 MPa)
Solubility Soluble in alcohol, CHCl3, CCl4, diethyl ether, acetone, acetic acid
Solubility in ethanediol 5.83 g/100 g (20 °C)
6.61 g/100 g (40 °C)
7.61 g/100 g (60 °C)
Solubility in ethanol 20 °C, solution in ethanol:
1.2 mL/L (20% v/v)
Solubility in acetone 20 °C, solution in acetone:
7.69 mL/L (38.46% v/v)
49.4 mL/L (62.5% v/v)
Solubility in diethylene glycol 52 g/100 g (20 °C)
log P 2.13
Vapor pressure 12.7 kPa (25 °C)
24.4 kPa (40 °C)
181 kPa (100 °C)
Conjugate acid Benzenium
Conjugate base Benzenide
UV-vismax) 255 nm
−54.8·10−6 cm3/mol
1.5011 (20 °C)
1.4948 (30 °C)
Viscosity 0.7528 cP (10 °C)
0.6076 cP (25 °C)
0.4965 cP (40 °C)
0.3075 cP (80 °C)
Trigonal planar
0 D
134.8 J/mol·K
173.26 J/mol·K
48.7 kJ/mol
-3267.6 kJ/mol
Occupational safety and health (OHS/OSH):
Main hazards
potential occupational carcinogen, flammable
GHS labelling:
GHS02: FlammableGHS06: ToxicGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
H225, H302, H304, H305, H315, H319, H340, H350, H372, H410
P201, P210, P301+P310, P305+P351+P338, P308+P313, P331
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
Flash point −11.63 °C (11.07 °F; 261.52 K)
497.78 °C (928.00 °F; 770.93 K)
Explosive limits 1.2–7.8%
Lethal dose or concentration (LD, LC):
930 mg/kg (rat, oral)
44,000 ppm (rabbit, 30 min)
44,923 ppm (dog)
52,308 ppm (cat)
20,000 ppm (human, 5 min)
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1 ppm, ST 5 ppm
REL (Recommended)
Ca TWA 0.1 ppm ST 1 ppm
IDLH (Immediate danger)
500 ppm
Safety data sheet (SDS) HMDB
Related compounds
Related compounds
Dewar benzene(isomer)
Supplementary data page
Benzene (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structures, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items because of its toxicity. Benzene is a volatile organic compound.

Benzene is classified as a carcinogen.[1]

« Back to Glossary Index