Cyclohexanol

Cyclohexanol[1]
Skeletal formula of cyclohexanol
Ball-and-stick model of the cyclohexanol molecule
Names
IUPAC name
Cyclohexanol
Other names
Cyclohexyl Alcohol,
hexahydrophenol,
hydrophenol,
hydroxycyclohexane,
Naxol
Hexalin
Hydralin
HOCy
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.003.301
EC Number 203-630-6
KEGG
RTECS number GV7875000
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 (pKa) 16
-73.40·10−6 cm3/mol
1.4641
Viscosity 41.07 mPa·s (30 °C)
Hazards
Main hazards Flammable, skin irritant
Reacts violently with oxidizing agents
Safety data sheet MSDS for cyclohexanol
R-phrases (outdated) R20 R22 R37 R38
S-phrases (outdated) S24 S25
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propaneHealth code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
4
3
0
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]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 50 ppm (200 mg/m3)[2]
REL (Recommended)
 TWA 50 ppm (200 mg/m3)[2]
IDLH (Immediate danger)
 400 ppm[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cyclohexanol is the organic compound with the formula HOCH(CH2)5. The molecule is related to cyclohexane ring 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. Billions of kilograms are produced annually, mainly as a precursor to nylon.[5]

Production

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

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. 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.[5]

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 somewhat toxic: the TLV 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.[6] Few studies have been done on its carcinogenicity, but one study on rats found it to have co-carcinogenic effects.[7]

References

  1. ↑ Merck Index, 11th Edition, 2731.
  2. 1 2 3 4 "NIOSH Pocket Guide to Chemical Hazards #0165". National Institute for Occupational Safety and Health (NIOSH).
  3. ↑ "Cyclohexanol". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. ↑ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  5. 1 2 3 4 Michael Tuttle Musser "Cyclohexanol and Cyclohexanone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
  6. ↑ CDC - NIOSH Pocket Guide to Chemical Hazards
  7. ↑ 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.
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