Cyclohexanol

Names Preferred IUPAC name Other names Identifiers ChEBI ChEMBL ChemSpider DrugBank ECHA InfoCard 100.003.301 Edit this at Wikidata EC Number KEGG RTECS number UNII Properties C₆H₁₂O Molar mass 100.158 g/mol Appearance Colorless, viscous liquid.
Hygroscopic Odor camphor-like Density 0.9624 g/mL, liquid Melting point 25.93 °C (78.67 °F; 299.08 K) Boiling point 161.84 °C (323.31 °F; 434.99 K) 3.60 g/100 mL (20 °C)
4.3 g/100 mL (30 °C) Solubility soluble in ethanol, ethyl ether, acetone, chloroform
miscible with ethyl acetate, linseed oil, benzene Vapor pressure 1 mmHg (20°C)^[2] 4.40 x 10⁻⁶ atm-cu m/mol Acidity (pK_a) 16 -73.40·10⁻⁶ cm³/mol 1.4641 Viscosity 41.07 mPa·s (30 °C) Hazards Occupational safety and health (OHS/OSH): Flammable, skin irritant
Reacts violently with oxidizing agents GHS labelling: GHS07: Exclamation mark Warning H302, H315, H332, H335 P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P312, P321, P330, P332+P313, P362, P403+P233, P405, P501 NFPA 704 (fire diamond) Flash point 67 °C (153 °F; 340 K) 300 °C (572 °F; 573 K) Explosive limits 2.7-12% Lethal dose or concentration (LD, LC): 2060 mg/kg (oral, rat)
2200-2600 mg/kg (oral, rabbit)^[3] NIOSH (US health exposure limits): TWA 50 ppm (200 mg/m³)^[2] TWA 50 ppm (200 mg/m³)^[2] 400 ppm^[2] Safety data sheet (SDS) MSDS for cyclohexanol

Cyclohexanol is the organic compound with the formula HOCH(CH₂)₅. The molecule is related to cyclohexane by replacement of one hydrogen atom by a hydroxyl group.^[4] This compound exists as a deliquescent colorless solid with a camphor-like odor, which, when very pure, melts near room temperature. Millions of tonnes are produced annually, mainly as a precursor to nylon.^[5]

Cyclohexanol is produced by the oxidation of cyclohexane in air, typically using cobalt catalysts:^[5]

2 C₆H₁₂ + O₂ → 2 C₆H₁₁OH

This process coforms cyclohexanone, and this mixture ("KA oil" for ketone-alcohol oil) is the main feedstock for the production of adipic acid. The oxidation involves radicals and the intermediacy of the hydroperoxide C₆H₁₁O₂H. Alternatively, cyclohexanol can be produced by the hydrogenation of phenol:

C₆H₅OH + 3 H₂ → C₆H₁₁OH

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

Cyclohexanol undergoes the main reactions expected for a secondary alcohol. Oxidation gives cyclohexanone, which is converted on a large scale in industry to the oxime, a precursor to caprolactam. As a laboratory exercise, this oxidation can be effected with chromic acid. Esterification affords the commercially useful derivatives dicyclohexyladipate and dicyclohexylphthalate, which are used as plasticizers. Heating in the presence of acid catalysts converts cyclohexanol to cyclohexene.^{[5] [6]}

Cyclohexanol has at least two solid phases. One of them is a plastic crystal.

As indicated above, cyclohexanol is an important feedstock in the polymer industry, firstly as a precursor to nylons, but also to various plasticizers. Small amounts are used as a solvent.

Cyclohexanol is moderately toxic: the Threshold Limit Value for the vapor for 8 h is 50 ppm.^[5] The IDLH concentration is set at 400 ppm, based on studies on the acute oral toxicity in animals.^[7] Few studies have been done on its carcinogenicity, but one study on rats found it to have co-carcinogenic effects.^[8]