Cyclohexene

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Cyclohexene
Olefine am Beispiel von Cycloalken-v2.svg
Cyclohexene for highscool.svg
Cyclohexene-conformation-2D-skeletal.png
Cyclohexen.png
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
ChemSpider
ECHA InfoCard 100.003.462
EC Number 203-807-8
RTECS number GW2500000
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R-phrases (outdated) R11, R19, R21/22
S-phrases (outdated) S16, S23, S24, S25, S33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
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., gasoline) Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored 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):
1946 mg/kg (oral, rat)
13,196 ppm (mouse, 2 hr)[2]
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 300 ppm (1015 mg/m3)[1]
REL (Recommended)
TWA 300 ppm (1015 mg/m3)[1]
IDLH (Immediate danger)
2000 ppm[1]
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

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.

Production and uses[edit]

Cyclohexene is produced by the partial hydrogenation of benzene, a process developed by the Asahi Chemical company.[citation needed] It is converted to cyclohexanol, which is dehydrogenated to give cyclohexanone, a precursor to caprolactam.[3] Cyclohexene is also a precursor to adipic acid, maleic acid, dicyclohexyladipate, and cyclohexene oxide. Furthermore, it is used as a solvent.

Laboratory experiments[edit]

Synthesis[edit]

A common experiment for beginning organic chemistry students[citation needed] is the acid-catalyzed dehydration of cyclohexanol with distillative removal of the resulting cyclohexene from the reaction mixture:

Cyclohexensynthese1.svg
Cyclohexensynthese2.svg

Oxidative cleavage[edit]

A green chemistry experiment is the oxidative cleavage of cyclohexene to form adipic acid. Hydrogen peroxide is used as the oxidant, in the presence of a tungsten catalyst.[4]

Structure[edit]

Cyclohexene is most stable in a half-chair conformation,[5] 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[edit]

External links[edit]

References[edit]

  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 and Health. National Institute for Occupational Safety and Health (NIOSH). 
  3. ^ Michael T. Musser "Cyclohexanol and Cyclohexanone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.doi:10.1002/14356007.a08_217
  4. ^ 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. 
  5. ^ 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.