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)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.462
EC Number
  • 203-807-8
RTECS number
  • GW2500000
UNII
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)
insoluble 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
Safety data sheet External MSDS
R-phrases (outdated) R11, R19, R21/22
S-phrases (outdated) S16, S23, S24, S25, S33
NFPA 704 (fire diamond)
Flammability code 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. gasolineHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
1
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):
1946 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]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Production and uses

Cyclohexene is produced by the partial hydrogenation of benzene, a process developed by the Asahi Chemical company.[3]

Reactions and uses

Benzene is converted to cyclohexylbenzene by acid-catalyzed alkylation with cyclohexene. Cyclohexylbenzene is a precursor to both phenol and cyclohexanone.[4]

Hydration of cyclohexene gives cyclohexanol, which can be dehydrogenated to give cyclohexanone, a precursor to caprolactam.[5]

The oxidative cleavage of cyclohexene gives adipic acid. Hydrogen peroxide is used as the oxidant, in the presence of a tungsten catalyst.[6]

Cyclohexene is also a precursor to maleic acid, dicyclohexyladipate, and cyclohexene oxide. Furthermore, it is used as a solvent.

Structure

Cyclohexene is most stable in a half-chair conformation,[7] 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
  • International Chemical Safety Card 1054
  • NIOSH Pocket Guide to Chemical Hazards. "#0167". National Institute for Occupational Safety and Health (NIOSH).
  • Material Safety Data Sheet for cyclohexene
  • Safety MSDS data
  • Reaction of Cyclohexene with Bromine and Potassium Permanganate
  • Cyclohexene synthesis
  • Data sheet at inchem.org

References
  1. "Cyclohexene". Immediately Dangerous to Life and 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. , Narisawa, Naoki & Katsutoshi Tanaka, "Cyclohexanol, method for producing cyclohexanol, and method for producing adipic acid"
  4. Plotkin, Jeffrey S. (2016-03-21). "What's New in Phenol Production?". American Chemical Society. Retrieved 2018-01-02.
  5. Musser, Michael T. (2005). "Cyclohexanol and Cyclohexanone". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_217.
  6. 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. doi:10.1021/ed077p1627.
  7. 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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