Cyclohexene

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.

Cyclohexene
Names
Preferred IUPAC name
Cyclohexene
Other names
Tetrahydrobenzene, 1,2,3,4-Tetrahydrobenzene, Benzenetetrahydride, Cyclohex-1-ene, Hexanaphthylene, UN 2256
Identifiers
3D model (JSmol)
906737
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.462
EC Number
  • 203-807-8
1659
RTECS number
  • GW2500000
UNII
  • InChI=1S/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2 checkY
    Key: HGCIXCUEYOPUTN-UHFFFAOYSA-N checkY
  • InChI=1/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2
    Key: HGCIXCUEYOPUTN-UHFFFAOYAQ
  • C1CCC=CC1
Properties
C6H10
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
1.4465
Hazards
GHS labelling:
GHS02: FlammableGHS06: ToxicGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Danger
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)
NFPA 704 four-colored diamond
1
3
0
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)[1]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 300 ppm (1015 mg/m3)[2]
REL (Recommended)
 TWA 300 ppm (1015 mg/m3)[2]
IDLH (Immediate danger)
 2000 ppm[2]
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).
checkY verify (what is checkY☒N ?)
Infobox references

Production and uses

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 uses

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]

Structure

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 also

References
  1. "Cyclohexene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  2. NIOSH Pocket Guide to Chemical Hazards. "#0167". 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.
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