Cyclohexanol is the

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

with the formula HOCH(CH₂)₅. The molecule is related to cyclohexane by replacement of one hydrogen atom by a hydroxyl group. This compound exists as a

deliquescent Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...

colorless solid with a camphor-like odor, which, when very pure, melts near room temperature. Billions of kilograms are produced annually, mainly as a precursor to

nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from pe ...

.Michael Tuttle Musser "Cyclohexanol and Cyclohexanone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.

Production

Cyclohexanol is produced by the

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

of cyclohexane in air, typically using cobalt

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

s: :C₆H₁₂ + 1/2 O₂ → C₆H₁₁OH This process co-forms cyclohexanone, and this mixture ("KA oil" for ketone-alcohol oil) is the main feedstock for the production of

adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula (CH2)4(COOH)2. From an industrial perspective, it is the most important dicarboxylic acid: about 2.5 billion kilograms of this white crystalline powder are produced annuall ...

. The oxidation involves radicals and the intermediacy of the hydroperoxide C₆H₁₁O₂H. Alternatively, cyclohexanol can be produced by the

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organ ...

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

: :C₆H₅OH + 3 H₂ → C₆H₁₁OH This process can also be adjusted to favor the formation of cyclohexanone.

Basic reactions

Cyclohexanol undergoes the main reactions expected for a

secondary alcohol In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...

. Oxidation gives cyclohexanone, which is converted on a large scale in industry to the

oxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted ...

, a precursor to caprolactam. As a laboratory exercise, this oxidation can be effected with

chromic acid The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixtu ...

Esterification In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

affords the commercially useful derivatives dicyclohexyladipate and dicyclohexylphthalate, which are used as

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticiz ...

s. Heating in the presence of acid catalysts converts cyclohexanol to cyclohexene.

Structure

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

plastic crystal A plastic crystal is a crystal composed of weakly interacting molecules that possess some orientational or conformational degree of freedom. The name plastic crystal refers to the mechanical softness of such phases: they resemble waxes and are easil ...

Applications

As indicated above, cyclohexanol is an important feedstock in the polymer industry, firstly as a precursor to

s, but also to various

plasticizers A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plastic ...

. Small amounts are used as a

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

Safety

Cyclohexanol is moderately toxic: the TLV for the vapor for 8 h is 50 ppm. The IDLH concentration is set at 400 ppm, based on studies on the acute oral toxicity in animals. Few studies have been done on its

carcinogenicity A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...

, but one study on rats found it to have co-carcinogenic effects.
Lucrecia Márquez-Rosado, Cristina Trejo-Solís 2, María del Pilar Cabrales-Romero, Evelia Arce-Popoca, Adolfo Sierra-Santoyo, Leticia Alemán-Lazarini, Samia Fatel-Fazenda, Claudia E. Carrasco-Legleu, Saúl Villa-Treviño, "Co-carcinogenic effect of cyclohexanol on the development of preneoplastic lesions in a rat hepatocarcinogenesis model", ''Molecular Carcinogenesis'', Vol. 46, No. 7, Pages 524 - 533, March 2007.

References

{{Chemical agents Cyclohexyl compounds Cycloalkanols Nerve agent precursors