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 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	906737
ChEBI	CHEBI:36404 ;
ChEMBL	ChEMBL16396 ;
ChemSpider	7788 ;
ECHA InfoCard	100.003.462
EC Number	203-807-8;
Gmelin Reference	1659
PubChem CID	8079;
RTECS number	GW2500000;
UNII	12L0P8F7GN ;
CompTox Dashboard (EPA)	DTXSID9038717 ;
	InChI InChI=1S/C6H10/c1-2-4-6-5-3-1/h1-2H,3-6H2 Key: HGCIXCUEYOPUTN-UHFFFAOYSA-N ; 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)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 300 ppm (1015 mg/m3)
REL (Recommended)	TWA 300 ppm (1015 mg/m3)
IDLH (Immediate danger)	2000 ppm
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). verify (what is ?) Infobox references

Cyclohexene is a hydrocarbon with the formula (CH₂)₄C₂H₂. It is an example of 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.

References

^ ^a ^b ^c NIOSH Pocket Guide to Chemical Hazards. "#0167". National Institute for Occupational Safety and Health (NIOSH).
^ "Cyclohexene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ 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.
^ US 9771313, Narisawa, Naoki & Tanaka, Katsutoshi, "Cyclohexanol, method for producing cyclohexanol, and method for producing adipic acid", published 26 Sep 2017
^ G. H. Coleman, H. F. Johnstone (1925). "Cyclohexene". Organic Syntheses. 5: 33. doi:10.15227/orgsyn.005.0033.
^ B. B. Corson, V. N. Ipatieff (1939). "Cyclohexylbenzene". Organic Syntheses. 19: 36. doi:10.15227/orgsyn.019.0036.
^ 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.
^ 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.
^ 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.
^ H. R. Snyder, L. A. Brooks (1932). "1,2-Dibromocyclohexane". Organic Syntheses. 12: 26. doi:10.15227/orgsyn.012.0026.
^ 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

[PGCH-1] 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] 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.

[acs_phenol-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.

[Ullmann-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.

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