Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light and air because it forms peroxides.

Olefine am Beispiel von Cycloalken-v2.svg
Cyclohexene for highscool.svg
Preferred IUPAC name
Other names
Tetrahydrobenzene, 1,2,3,4-Tetrahydrobenzene, Benzenetetrahydride, Cyclohex-1-ene, Hexanaphthylene, UN 2256
3D model (JSmol)
ECHA InfoCard 100.003.462 Edit this at Wikidata
EC Number
  • 203-807-8
RTECS number
  • GW2500000
  • InChI=1S/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2 checkY
  • InChI=1/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2
  • C1CCC=CC1
Molar mass 82.143 g/mol
Appearance colorless liquid
Odor sweet
Density 0.8110 g/cm3
Melting point −103.5 °C (−154.3 °F; 169.7 K)
Boiling point 82.98 °C (181.36 °F; 356.13 K)
slightly soluble in water
Solubility miscible with organic solvents
Vapor pressure 8.93 kPa (20 °C)

11.9 kPa (25 °C)

0.022 mol·kg−1·bar−1
-57.5·10−6 cm3/mol
GHS labelling:
GHS02: FlammableGHS06: ToxicGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
H225, H302, H305, H311, H411
P210, P233, P240, P241, P242, P243, P264, P270, P273, P280, P301+P310, P301+P312, P302+P352, P303+P361+P353, P312, P322, P330, P331, P361, P363, P370+P378, P391, P403+P235, P405, P501
NFPA 704 (fire diamond)
Flash point −12 °C (10 °F; 261 K)
244 °C (471 °F; 517 K)
Explosive limits 0.8–5 %
Lethal dose or concentration (LD, LC):
1407 mg/kg (oral, rat)
13,196 ppm (mouse, 2 hr)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 300 ppm (1015 mg/m3)[1]
REL (Recommended)
TWA 300 ppm (1015 mg/m3)[1]
IDLH (Immediate danger)
2000 ppm[1]
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production and usesEdit

Cyclohexene is produced by the partial hydrogenation of benzene, a process developed by the Asahi Chemical company.[3] In the laboratory, it can be prepared by dehydration of cyclohexanol.[4]


Reactions and usesEdit

Benzene is converted to cyclohexylbenzene by acid-catalyzed alkylation with cyclohexene.[5] Cyclohexylbenzene is a precursor to both phenol and cyclohexanone.[6]

Hydration of cyclohexene gives cyclohexanol, which can be dehydrogenated to give cyclohexanone, a precursor to caprolactam.[7]

The oxidative cleavage of cyclohexene gives adipic acid. Hydrogen peroxide is used as the oxidant in the presence of a tungsten catalyst.[8] Bromination gives 1,2-dibromocyclohexane.[9]


Cyclohexene is most stable in a half-chair conformation,[10] unlike the preference for a chair form of cyclohexane. One basis for the cyclohexane conformational preference for a chair is that it allows each bond of the ring to adopt a staggered conformation. For cyclohexene, however, the alkene is planar, equivalent to an eclipsed conformation at that bond.

See alsoEdit


  1. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0167". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ "Cyclohexene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ US 9771313, Narisawa, Naoki & Tanaka, Katsutoshi, "Cyclohexanol, method for producing cyclohexanol, and method for producing adipic acid", published 26 Sep 2017 
  4. ^ G. H. Coleman, H. F. Johnstone (1925). "Cyclohexene". Organic Syntheses. 5: 33. doi:10.15227/orgsyn.005.0033.
  5. ^ B. B. Corson, V. N. Ipatieff (1939). "Cyclohexylbenzene". Organic Syntheses. 19: 36. doi:10.15227/orgsyn.019.0036.
  6. ^ Plotkin, Jeffrey S. (2016-03-21). "What's New in Phenol Production?". American Chemical Society. Archived from the original on 2019-10-27. Retrieved 2018-01-02.
  7. ^ Musser, Michael T. (2005). "Cyclohexanol and Cyclohexanone". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_217.
  8. ^ Reed, Scott M.; Hutchison, James E. (2000). "Green Chemistry in the Organic Teaching Laboratory: An Environmentally Benign Synthesis of Adipic Acid". J. Chem. Educ. 77 (12): 1627–1629. Bibcode:2000JChEd..77.1627R. doi:10.1021/ed077p1627.
  9. ^ H. R. Snyder, L. A. Brooks (1932). "1,2-Dibromocyclohexane". Organic Syntheses. 12: 26. doi:10.15227/orgsyn.012.0026.
  10. ^ Jensen, Frederick R.; Bushweller, C. Hackett (1969). "Conformational preferences and interconversion barriers in cyclohexene and derivatives". J. Am. Chem. Soc. 91 (21): 5774–5782. doi:10.1021/ja01049a013.

External linksEdit