Cyclohexanone

Not to be confused with Cyclexanone.

Cyclohexanone

Skeletal formula of cyclohexanone Skeletal formula of cyclohexanone Ball-and-stick model of cyclohexanone Ball-and-stick model of cyclohexanone
Skeletal formula viewed side-on, showing the non-planar conformation Skeletal formula viewed side-on, showing the non-planar conformation Ball-and-stick model of cyclohexanone viewed side-on, showing the non-planar conformation Ball-and-stick model of cyclohexanone viewed side-on, showing the non-planar conformation
Names
Preferred IUPAC name Cyclohexanone
Other names oxocyclohexane, pimelic ketone, ketohexamethylene, cyclohexyl ketone, ketocyclohexane, hexanon, Hydrol-O, Sextone, K, Anone
Identifiers
CAS Number	108-94-1 checkY
3D model (JSmol)	Interactive image
ChEBI	CHEBI:17854 checkY
ChEMBL	ChEMBL18850 checkY
ChemSpider	7679 checkY
DrugBank	DB02060 checkY
ECHA InfoCard
EC Number	203-631-1
E number
KEGG	C00414 checkY
PubChem CID	7967
UNII	5QOR3YM052 checkY
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/C6H10O/c7-6-4-2-1-3-5-6/h1-5H2 checkY Key: JHIVVAPYMSGYDF-UHFFFAOYSA-N checkY InChI=1/C6H10O/c7-6-4-2-1-3-5-6/h1-5H2 Key: JHIVVAPYMSGYDF-UHFFFAOYAY
SMILES C1CCC(=O)CC1
Properties
Chemical formula	C6H10O
Molar mass	98.15 g/mol
Appearance	Colorless liquid
Odor	Peppermint or acetone-like
Density	0.9478 g/mL, liquid
Melting point	−47 °C (−53 °F; 226 K)
Boiling point	155.65 °C (312.17 °F; 428.80 K)
Solubility in water	8.6 g/100 mL (20 °C)
Solubility in all organic solvents	Miscible
log P	0.81
Vapor pressure	5 mmHg (20 °C)
Magnetic susceptibility (χ)	−62.04·10−6 cm3/mol
Refractive index (nD)	1.447
Viscosity	2.02 cP at 25 °C
Thermochemistry
Std molar entropy (S⦵298)	+229.03 J·K−1·mol−1
Std enthalpy of formation (ΔfH⦵298)	−270.7 kJ·mol−1
Std enthalpy of combustion (ΔcH⦵298)	−3519.3 kJ·mol−1
Hazards
GHS labelling:
Pictograms	GHS02: FlammableGHS05: CorrosiveGHS07: Exclamation mark
Signal word	Danger
Hazard statements	H226, H302, H305, H312, H315, H318, H332
Precautionary statements	P280, P305+P351+P338
NFPA 704 (fire diamond)	1 2 0
Flash point	44 °C (111 °F; 317 K)
Autoignition temperature	420 °C (788 °F; 693 K)
Explosive limits	1.1–9.4%
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1200 mg/kg (cat, orally); 2362 mg/kg (rat, orally)
LC50 (median concentration)	8000 ppm (rat, 4 hr)
LCLo (lowest published)	4706 ppm (mouse, 1.5 hr)
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 50 ppm (200 mg/m3)
REL (Recommended)	TWA 25 ppm (100 mg/m3) [skin]
IDLH (Immediate danger)	700 ppm
Related compounds
Related ketones	Cyclopentanone, cycloheptanone
Related compounds	Cyclohexanol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). checkY verify (what is checkY☒N ?) Infobox references

Cyclohexanone is the organic compound with the formula (CH₂)₅CO. The molecule consists of six-carbon cyclic molecule with a ketone functional group. This colorless oily liquid has a sweet odor reminiscent of benzaldehyde. Over time, samples of cyclohexanone assume a pale yellow color.

Cyclohexanone is slightly soluble in water and miscible with common organic solvents. Millions of tonnes are produced annually, mainly as a precursor to nylon.

History and synthesis

The compound was discovered by Edmund Drechsel in 1888 among the products of AC electrolysis of slightly acidified water solutions of phenol. He named it hydrophenoketone and correctly suggested that phenol was first hydrogenated by electrolytic hydrogen to cyclohexanol, which he wasn't able to isolate, and then oxidized by electrolytic oxygen.

Laboratory synthesis

Cyclohexanone can be prepared from cyclohexanol by oxidation with chromium trioxide (Jones oxidation). An alternative method utilizes the safer and more readily available oxidant sodium hypochlorite.

Industrial production

Cyclohexanone is produced by the oxidation of cyclohexane in air, typically using cobalt catalysts:

C₆H₁₂ + O₂ → (CH₂)₅CO + H₂O

This process forms cyclohexanol as a by-product, and this mixture, called "KA Oil" for ketone-alcohol oil, is the main feedstock for the production of adipic acid. The oxidation involves radicals and the hydroperoxide C₆H₁₁O₂H as an intermediate. In some cases, purified cyclohexanol, obtained by hydration of cyclohexene, is the precursor. Alternatively, cyclohexanone can be produced by the partial hydrogenation of phenol:

C₆H₅OH + 2 H₂ → (CH₂)₅CO

This process can also be adjusted to favor the formation of cyclohexanol.

ExxonMobil developed a process in which benzene is hydroalkylated to cyclohexylbenzene. This latter product is oxidized to a hydroperoxide and then cleaved into phenol and cyclohexanone. Therefore, this newer process without producing the acetone by-product appears attractive and is similar to the cumene process as a hydroperoxide is formed and then decomposed to yield two key products.

Uses

The great majority of cyclohexanone is consumed in the production of precursors to Nylon 6,6 and Nylon 6. About half of the world's supply is converted to adipic acid, one of two precursors for nylon 6,6. For this application, the KA oil (see above) is oxidized with nitric acid. The other half of the cyclohexanone supply is converted to cyclohexanone oxime. In the presence of sulfuric acid catalyst, the oxime rearranges to caprolactam, a precursor to nylon 6:

File:Caprolactam Synth.png

Other reactions

In addition to the large scale reactions conducted in service of the polymer industry, many reactions have been developed for cyclohexanone.

In the presence of light, it undergoes alpha-chlorination to give 2-chlorocyclohexanone. It forms a trimethylsilylenol ether upon treatment with trimethylsilylchloride in the presence of base.

It forms an enamine with pyrrolidine.

Self condensation of cyclohexanone gives cyclohexenylcyclohexanone. The latter undergoes dehydrogenation to give 2-phenylphenol.

Treatment with nitrosyl chloride and ethanol in sulfur dioxide gives the oximinecarboxylic ester:

(CH₂)₅CO + C₂H₅OH + NOCl → HON=CH(CH₂)₄CO₂C₂H₅ + HCl

Illicit use

Cyclohexanone has been used in the illicit production of phencyclidine and its analogs and is often subject to purchase restrictions, such as being listed on the Special Surveillance List in the US.

Safety

Like cyclohexanol, cyclohexanone is not carcinogenic and is moderately toxic, with a TLV of 25 ppm for the vapor. It is an irritant.