Cyclohexane

Cyclohexane

Names
Preferred IUPAC name Cyclohexane
Other names Hexanaphthene
Identifiers
CAS Number	110-82-7 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:29005 Y
ChEMBL	ChEMBL15980 Y
ChemSpider	7787 Y
DrugBank	DB03561 Y
ECHA InfoCard	100.003.461
KEGG	C11249 Y
PubChem	8078
UNII	48K5MKG32S Y
InChI InChI=1S/C6H12/c1-2-4-6-5-3-1/h1-6H2 Y Key: XDTMQSROBMDMFD-UHFFFAOYSA-N Y InChI=1/C6H12/c1-2-4-6-5-3-1/h1-6H2 Key: XDTMQSROBMDMFD-UHFFFAOYAZ
SMILES C1CCCCC1
Properties
Chemical formula	C6H12
Molar mass	84.16 g·mol−1
Appearance	Colorless liquid
Odor	Sweet, gasoline-like
Density	0.7781 g/mL, liquid
Melting point	6.47 °C (43.65 °F; 279.62 K)
Boiling point	80.74 °C (177.33 °F; 353.89 K)
Solubility in water	Immiscible
Solubility	Soluble in ether, alcohol, acetone Miscible with olive oil
Vapor pressure	78 mmHg (20 °C)
Magnetic susceptibility (χ)	-68.13·10−6 cm3/mol
Refractive index (nD)	1.42662
Viscosity	1.02 cP at 17 °C
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-156 kJ/mol
Std enthalpy of combustion (ΔcHo298)	-3920 kJ/mol
Hazards
Safety data sheet	See: data page
EU classification (DSD)	F Xn N
R-phrases	R11, R38, R65, R67, R50/53
S-phrases	(S2), S9, S16, S25, S33, S60, S61, S62
NFPA 704	3 1 0
Flash point	−20 °C (−4 °F; 253 K)
Autoignition temperature	245 °C (473 °F; 518 K)
Explosive limits	1.3%-8%
Lethal dose or concentration (LD, LC):
LD50 (median dose)	12705 mg/kg (rat, oral) 813 mg/kg (mouse, oral)
LCLo (lowest published)	17,142 ppm (mouse, 2 hr) 26,600 ppm (rabbit, 1 hr)
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 300 ppm (1050 mg/m3)
REL (Recommended)	TWA 300 ppm (1050 mg/m3)
IDLH (Immediate danger)	1300 ppm
Related compounds
Related cycloalkanes	Cyclopentane Cycloheptane
Related compounds	Cyclohexene Benzene
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Cyclohexane is a cycloalkane with the molecular formula C₆H₁₂ (abbreviated to Cy). Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used).

On an industrial scale, cyclohexane is produced by hydrogenation of benzene. Producers of cyclohexane accounts for approximately 11.4% of global demand for benzene. The reaction is highly exothermic, with ΔH(500 K) = 216.37 kJ/mol). Dehydrogenation commenced noticeably above 300 °C, reflecting the favorable entropy for dehydrogenation.

Unlike benzene, cyclohexane is not easily obtained from natural resources such as coal. For this reason, early investigators synthesized their cyclohexane samples.

Surprisingly their cyclohexanes boiled higher by 10°C than either hexahydrobenzene or hexanaphtene but this riddle was solved in 1895 by Markovnikov, N.M. Kishner, and Nikolay Zelinsky when they reassigned "hexahydrobenzene" and "hexanaphtene" as methylcyclopentane, the result of an unexpected rearrangement reaction.

In 1894 Baeyer synthesized cyclohexane starting with a Dieckmann condensation of pimelic acid followed by multiple reductions:

In the same year E. Haworth and W.H. Perkin Jr. (1860–1929) prepared it via a Wurtz reaction of 1,6-dibromohexane.

Cyclohexane is rather unreactive, being a non-polar, hydrophobic hydrocarbon. It reacts with superacids, such as HF + SbF₅, which will lead to cracking. Substituted cyclohexanes, however, may be reactive under a variety of conditions, many of which are important in organic chemistry.