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Benzene

Athanor · official

C6H6 · 78.11 g/mol

Also called benzol, phenyl, cyclohexatriene

Open in Athanor
The structure of Benzene
Drawn from its SMILES with RDKit310
FlammableHarmful or irritantHealth hazardDangerHighly Flammable liquid and vapor · May be fatal if swallowed and enters airways · Causes skin irritation · Causes serious eye irritation · May cause genetic defects · May cause cancer

Names and identifiers

IUPAC name
benzene
Synonyms
benzol, phenyl, cyclohexatriene
+ 37 more

Cyclohexatriene, benzole, Pyrobenzole, Benzine, Coal naphtha, Pyrobenzol, Benzen, Phene, Phenyl hydride, Mineral naphtha, Benzolene, Bicarburet of hydrogen, Motor benzol, Benzeen, Benzolo, Fenzen, (6)Annulene, [6]Annulene, Nitration benzene, Benzol 90, NCI-C55276, 1,3,5-cyclohexatriene, Benzine (Obs.), Rcra waste number U019, Benzin (Obs.), Benzinum, DTXSID3039242, CHEBI:16716, AI3-00808, NSC-67315, DTXCID20135, J64922108F, NSC67315, RefChem:6619, HEADACHE INSOMNIA, 200-753-7, Benzin

Molecular formula
C6H6
Empirical formula
CH
Molecular weight
78.11 g/mol
Exact mass
78.04695
CAS number
71-43-2
PubChem CID
241
Canonical SMILES
C1=CC=CC=C1
Isomeric SMILES
C1=CC=CC=C1
InChI
InChI=1S/C6H6/c1-2-4-6-5-3-1/h1-6H
InChIKey
UHOVQNZJYSORNB-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity
Appearance
Colorless to light-yellow liquid [Note: A solid below 42 degrees F][6]
7 values

From Hazardous Substances Data Bank (HSDB), the most authoritative source here.

ValueAs writtenSource
–Benzene appears as a clear colorless liquid with a petroleum-like odor. Flash point less than 0 °F. Less dense than water and slightly soluble in water. Hence floats on water. Vapors are heavier than air.[1] CAMEO Chemicals
–CBI; Gas Vapor; Liquid; Gas Vapor; Liquid[2] EPA Chemical Data Reporting (CDR)
–COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR.[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–Highly flammable colorless to light-yellow liquid with a petroleum-like odor.[4] Occupational Safety and Health Administration (OSHA)
–Colorless to light-yellow liquid with an aromatic odor. [Note: A solid below 42 °F.][5] The National Institute for Occupational Safety and Health (NIOSH)
–Clear, colorless to light yellow liquid at room temperature. Benzene is a solid below 42°F (5.6°C).[5] The National Institute for Occupational Safety and Health (NIOSH)
–shownColorless to light-yellow liquid [Note: A solid below 42 degrees F][6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Odor
Aromatic odor[6]
2 values

From Hazardous Substances Data Bank (HSDB), the most authoritative source here.

ValueAs writtenSource
–shownAromatic odor[6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
–Gasoline-like odor; rather pleasant aromatic odor. Odor threshold = 4.68 ppm.[6] Hazardous Substances Data Bank (HSDB)cites Sax, N.I. Dangerous Properties of Industrial Materials. 6th ed. New York, NY: Van Nostrand Reinhold, 1984., p. 152
Melting point
5.49 °C[7]
5 values

5 of 5 sources agree on it (most common value).

ValueAs writtenSource
5.5 °C41.9 °F (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
6 °C6 °C[3] ILO-WHO International Chemical Safety Cards (ICSCs)
5.5 °C41.9 °F[4] Occupational Safety and Health Administration (OSHA)
5.5 °Cshown5.49 °C[7] PAC Chemical Database, U.S. Department of Energy
6 °C42 °F[5] The National Institute for Occupational Safety and Health (NIOSH)
Boiling point
80.09 °C @760 [mmHg][7]
5 values

5 of 5 sources agree on it (most common value).

ValueAs writtenSource
80.1 °C176.2 °F at 760 mmHg (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
80 °C80 °C[3] ILO-WHO International Chemical Safety Cards (ICSCs)
80.1 °C176.2 °F[4] Occupational Safety and Health Administration (OSHA)
80.1 °Cshown80.09 °C @760 [mm Hg][7] PAC Chemical Database, U.S. Department of Energy
80 °C176 °F[5] The National Institute for Occupational Safety and Health (NIOSH)
Density
0.8765 @ 20°C[7]
5 values

5 of 5 sources agree on it (most common value).

ValueAs writtenSource
–0.879 at 68 °F (USCG, 1999) - Less dense than water[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–Relative density (water = 1): 0.88[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–0.88[4] Occupational Safety and Health Administration (OSHA)
–shown0.8765 @ 20°C[7] PAC Chemical Database, U.S. Department of Energy
–0.88[5] The National Institute for Occupational Safety and Health (NIOSH)

3 more values were reported but failed the checks (unreadable or out of range), so they are not shown.

Solubility in water
Solubility in water, g/100ml at 25 °C: 0.18[3]
4 values

From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.

ValueAs writtenSource
–1 to 5 mg/mL at 64 °F (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–In water, 1.79X10+3 mg/L at 25 °C[6] Hazardous Substances Data Bank (HSDB)cites May WE et al; J Chem Ref Data 28: 197-0200 (1983)
–shownSolubility in water, g/100ml at 25 °C: 0.18[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–0.07%[5] The National Institute for Occupational Safety and Health (NIOSH)
log P
2.13[3]
2 values

2 of 2 sources agree on it (most common value).

ValueAs writtenSource
–log Kow = 2.13[6] Hazardous Substances Data Bank (HSDB)cites Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 18
–shown2.13[3] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure
Vapor pressure, kPa at 20 °C: 10[3]
5 values

3 of 4 sources agree on it (most common value).

ValueAs writtenSource
60 mmHg60 mmHg at 59 °F[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
76 mmHg76 mmHg at 68 °F (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
94.8 mmHg94.8 mm Hg at 25 °C[6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989., p. 361
75 mmHgshownVapor pressure, kPa at 20 °C: 10[3] ILO-WHO International Chemical Safety Cards (ICSCs)
75 mmHg75 [mm Hg] @20 °C[7] PAC Chemical Database, U.S. Department of Energy

2 more values were reported but failed the checks (unreadable or out of range), so they are not shown.

Flash point
-11.0 °C (12.2 °F) (Closed cup)[6]
5 values

5 of 5 sources agree on it (most common value).

ValueAs writtenSource
−11 °C12 °F (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
−11.0 °Cshown-11.0 °C (12.2 °F) (Closed cup)[6] Hazardous Substances Data Bank (HSDB)cites Sigma-Aldrich; Material Safety Data Sheet for Benzene. Product Number: 12540, Version 5.2 (Revision Date 06/23/2014). Available from, as of October 9, 2014: https://www.sigmaaldrich.com/safety-center.html
−11 °C-11 °C c.c.[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−11 °C12 °F[4] Occupational Safety and Health Administration (OSHA)
−11 °C12 °F[5] The National Institute for Occupational Safety and Health (NIOSH)
Autoignition temperature
498 °C[3]
3 values

2 of 3 sources agree on it (most common value).

ValueAs writtenSource
592 °C1097 °F (USCG, 1999)[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
498 °C928 °F (498 °C)[6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-18
498 °Cshown498 °C[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms
6
Rings
1
Aromatic rings
1
Fraction sp³ carbons (Fsp3)
0
H-bond donors
0
H-bond acceptors
0
Rotatable bonds
0
TPSA (Ų)
0
Formal charge
0
XLogP3
2.1 PubChem
Complexity
15 PubChem
Stereocenters
None
Double-bond geometry
None specified
Point group
D6h of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C92.26%
  • H7.74%

Isotope pattern

100%78.0476.6%79.05080.054

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
1.69 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-2.13 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
1 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 78.11
  • log P ≤ 5 (Crippen): 1.69
  • H-bond donors ≤ 5: 0
  • H-bond acceptors ≤ 10: 0

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Harmonized EU classification (CLP Annex VI). Source [8].

  • Flammable
  • Harmful or irritant
  • Health hazard
310
NFPA 704[6]
  • H225Highly Flammable liquid and vapor
  • H304May be fatal if swallowed and enters airways
  • H315Causes skin irritation
  • H319Causes serious eye irritation
  • H340May cause genetic defects
  • H350May cause cancer

Precautionary statements: P203, P210, P233, P240, P241, P242, P243, P260, P264, P264+P265, P270, P280, P301+P316, P302+P352, P303+P361+P353, P305+P351+P338, P318, P319, P321, P331, P332+P317, P337+P317, P362+P364, P370+P378, P403+P235, P405, P501

View all classifications (4)
  • [8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH225, H304, H315, H319, H340, H350
  • [9] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 0.1% (2 of 1934) of reports.
  • [9] European Chemicals Agency (ECHA) · 1,934 reports · DangerH225, H304, H315, H319, H340, H350, H372, H412
  • [6] Hazardous Substances Data Bank (HSDB) · DangerH225, H304, H315, H319, H340, H350, H401

Exposure limits

  • PEL-TWA (8-Hour Time Weighted Average): 1 ppm[4]
  • PEL-STEL (Short Term Exposure Limit): 5 ppm[4]
  • PEL: [1910.1028] TWA 1 ppm ST 5 ppm See Appendix F[5]
  • REL-TWA (Time Weighted Average): 0.1 ppm[4]
  • REL: Ca TWA 0.1 ppm ST 1 ppm See Appendix A[5]
  • TLV: 0.5 ppm as TWA; 2.5 ppm as STEL; (skin); A1 (confirmed human carcinogen); BEI issued.[3]

First aid

  • Eyes: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. Immediately transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. Skin: Immediately flood affected skin with water while removing and isolating all contaminated clothing.[1]
  • General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[10]
  • (General first aid procedures) Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: Soap wash immediately - If this chemical contacts the skin, immediately wash the contaminated skin with soap and water.[5]
  • Fresh air, rest. Refer for medical attention.[3]

Storage

  • Fireproof. Separated from food and feedstuffs, oxidants and halogens. Store in an area without drain or sewer access.[3]
  • Precautions FOR "carcinogens": Storage site should be as close as practicable to lab in which carcinogens are to be used, so that only small quantities required for ... Expt need to be carried. Carcinogens should be kept in only one section of cupboard, an explosion-proof refrigerator or freezer (depending on chemicophysical properties ...) that bears appropriate label. An inventory ... Should be kept, showing quantity of carcinogen & date it was acquired ... Facilities for dispensing ... Should be contiguous to storage area. (chemical Carcinogens)[6]
  • Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.[6]

Incompatibilities

  • Reacts violently with iodine pentafluoride.[6]
  • Hydrogenation of benzene to cyclohexane was effected in a fixed bed reactor at 210-230 °C, but a fall in conversion was apparent. Increasing the bed temp by 10 °C & the hydrogen flow led to a large increase in reaction rate which the interbed cooling coils could not handle, & an exotherm to 280 °C developed, with a hot spot around 600 °C which bulged the reactor wall.[6]
  • Benzene ... Ignites in contact with (iodine heptafluoride) gas ...[6]
  • Dioxygenyl tetrafluoroborate is a very powerful oxidant, addition of a small particle to small samples of benzene ... At ambient temp ... (caused) ignition.[6]

Safety data sheets on the supplier’s page: Aladdin Scientific, CATO Research Chemicals Inc., Sigma-Aldrich.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
  2. [2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
  3. [3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  4. [4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
  5. [5]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
  6. [6]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
  7. [7]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
  8. [8]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
  9. [9]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  10. [10]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
  11. [11]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
  12. [12]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  13. [13]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  14. [14]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  15. [15]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
  16. [16]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
  17. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  18. ·Literature on PubChem

Data last updated 2026-10-14.