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.<ref>Template:RubberBible86th</ref> 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.<ref name=Ullmann>Michael Tuttle Musser "Cyclohexanol and Cyclohexanone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.</ref>

Production

Cyclohexanol is produced by the oxidation of cyclohexane in air, typically using cobalt catalysts:<ref name=Ullmann/>

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.

Basic reactions

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.<ref name=Ullmann/><ref>Template:Cite journal</ref>

Structure

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

Applications

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.

Safety

Cyclohexanol is moderately toxic: the Threshold Limit Value for the vapor for 8 h is 50 ppm.<ref name=Ullmann/> The IDLH concentration is set at 400 ppm, based on studies on the acute oral toxicity in animals.<ref>CDC - NIOSH Pocket Guide to Chemical Hazards</ref> Few studies have been done on its carcinogenicity, but one study on rats found it to have co-carcinogenic effects.<ref>[1] 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.</ref>

References

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