Cyclohexene

Cyclohexene

Names
Preferred IUPAC name Cyclohexene
Other names Tetrahydrobenzene, 1,2,3,4-Tetrahydrobenzene, Benzenetetrahydride, Cyclohex-1-ene, Hexanaphthylene, UN 2256
Identifiers
CAS Number	110-83-8  Y
3D model (JSmol)	Interactive image
Beilstein Reference	906737
ChEBI	CHEBI:36404  Y
ChEMBL	ChEMBL16396  Y
ChemSpider	7788  Y
ECHA InfoCard	100.003.462
EC Number	203-807-8
Gmelin Reference	1659
PubChem CID	8079
RTECS number	GW2500000
UNII	12L0P8F7GN  Y
CompTox Dashboard (EPA)	DTXSID9038717
InChI InChI=1S/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2 Y Key: HGCIXCUEYOPUTN-UHFFFAOYSA-N Y InChI=1/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2 Key: HGCIXCUEYOPUTN-UHFFFAOYAQ
SMILES C1CCC=CC1
Properties
Chemical formula	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)
Solubility in water	slightly soluble in water
Solubility	miscible with organic solvents
Vapor pressure	8.93 kPa (20 °C) 11.9 kPa (25 °C)
Henry's law constant  (kH)	0.022 mol·kg−1·bar−1
Magnetic susceptibility (χ)	−57.5·10−6 cm3/mol
Refractive index (nD)	1.4465
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H302, H305, H311, H411
Precautionary statements	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)	1 3 0
Flash point	−12 °C (10 °F; 261 K)
Autoignition temperature	244 °C (471 °F; 517 K)
Explosive limits	0.8–5%
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1407 mg/kg (oral, rat)
LCLo (lowest published)	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). Y  verify  (what is  YN ?) Infobox references

Cyclohexene is a hydrocarbon with the formula (CH₂)₄C₂H₂. It is a cycloalkene. At room temperature, cyclohexene is a colorless liquid with a sharp odor. Among its uses, it is an intermediate in the commercial synthesis of nylon. ^[3]

Production and uses

Cyclohexene is produced by the partial hydrogenation of benzene, a process developed by the Asahi Chemical company. ^[4] The main product of the process is cyclohexane because cyclohexene is more easily hydrogenated than benzene.

In the laboratory, it can be prepared by dehydration of cyclohexanol. ^[5]

C₆H₁₁OH → C₆H₁₀ + H₂O

Reactions and uses

Benzene is converted to cyclohexylbenzene by acid-catalyzed alkylation with cyclohexene. ^[6] Cyclohexylbenzene is a precursor to both phenol and cyclohexanone. ^[7]

Hydration of cyclohexene gives cyclohexanol, which can be dehydrogenated to give cyclohexanone, a precursor to caprolactam. ^[8]

The oxidative cleavage of cyclohexene gives adipic acid. Hydrogen peroxide is used as the oxidant in the presence of a tungsten catalyst. ^[9]

1,5-Hexadiene is produced by ethenolysis of cyclohexene. Bromination gives 1,2-dibromocyclohexane. ^[10]

Structure

Cyclohexene is most stable in a half-chair conformation, ^[11] 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

• Diels-Alder reaction
• Cyclohexa-1,3-diene
• Cyclohexa-1,4-diene

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. Xie, Feng; Chen, Lihang; Cedeño Morales, Eder Moisés; Ullah, Saif; Fu, Yiwen; Thonhauser, Timo; Tan, Kui; Bao, Zongbi; Li, Jing (2024). "Complete separation of benzene-cyclohexene-cyclohexane mixtures via temperature-dependent molecular sieving by a flexible chain-like coordination polymer". Nature Communications. 15 (1): 2240. Bibcode:2024NatCo..15.2240X. doi:10.1038/s41467-024-46556-6. PMC   10933443 . PMID   38472202.
4. US 9771313,Narisawa, Naoki&Tanaka, Katsutoshi,"Cyclohexanol, method for producing cyclohexanol, and method for producing adipic acid",published 26 Sep 2017 
5. G. H. Coleman, H. F. Johnstone (1925). "Cyclohexene". Organic Syntheses. 5: 33. doi:10.15227/orgsyn.005.0033.
6. B. B. Corson, V. N. Ipatieff (1939). "Cyclohexylbenzene". Organic Syntheses. 19: 36. doi:10.15227/orgsyn.019.0036.
7. 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.
8. Musser, Michael T. (2005). "Cyclohexanol and Cyclohexanone". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_217. ISBN   978-3-527-30673-2.
9. 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.
10. H. R. Snyder, L. A. Brooks (1932). "1,2-Dibromocyclohexane". Organic Syntheses. 12: 26. doi:10.15227/orgsyn.012.0026.
11. 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 links

• 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