Phenethyl alcohol

Phenethyl alcohol, or 2-phenylethanol, is the organic compound that consists of a phenethyl group (C6H5CH2CH2) group attached to OH. It is a colourless liquid that is slightly soluble in water (2 ml/100 ml H2O), but miscible with most organic solvents. It occurs widely in nature, being found in a variety of essential oils. It has a pleasant floral odor.

Phenethyl alcohol[1]
Names
Preferred IUPAC name
2-Phenylethan-1-ol
Other names
2-Phenylethanol
Phenethyl alcohol
Benzyl carbinol
β-Hydroxyethylbenzene
Benzeneethanol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.415
UNII
Properties
C8H10O
Molar mass 122.16 g/mol
Odor Soft, like roses
Density 1.017 g/cm3
Melting point −27 °C (−17 °F; 246 K)
Boiling point 219 to 221 °C (426 to 430 °F; 492 to 494 K)
log P 1.36 [2]
Hazards
Safety data sheet JT Baker MSDS
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
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

Synthesis

Phenethyl alcohol is prepared commercially via two routes. Most common is the Friedel-Crafts reaction between benzene and ethylene oxide in the presence of aluminium trichloride.

C6H6 + CH2CH2O + AlCl3 → C6H5CH2CH2OAlCl2 + HCl

The reaction affords the aluminium alkoxide that is subsequently hydrolyzed to the desired product. The main side product is diphenylethane, which can be avoided by use of excess benzene. Hydrogenation of styrene oxide also affords phenethyl alcohol.[3]

Laboratory methods

Phenethyl alcohol can also be prepared by the reaction between phenylmagnesium bromide and ethylene oxide:

C6H5MgBr + CH2CH2O → C6H5CH2CH2OMgBr
C6H5CH2CH2OMgBr + H+ → C6H5CH2CH2OH

Phenethyl alcohol can also be produced by biotransformation from L-phenylalanine using immobilized yeast Saccharomyces cerevisiae.[4] It is also possible to produce phenethyl alcohol by the reduction of phenylacetic acid using sodium borohydride and iodine in THF. [5]

Occurrence and uses

Phenethyl alcohol is found in extract of rose, carnation, hyacinth, Aleppo pine, orange blossom, ylang-ylang, geranium, neroli, and champaca. It is also an autoantibiotic produced by the fungus Candida albicans [6]

It is therefore a common ingredient in flavors and perfumery, particularly when the odor of rose is desired.[3] It is used as an additive in cigarettes. It is also used as a preservative in soaps due to its stability in basic conditions. It is of interest due to its antimicrobial properties.

See also

References
  1. Merck Index (11th ed.). p. 7185.
  2. "Phenylethyl alcohol_msds".
  3. Fahlbusch, Karl-Georg; Hammerschmidt, Franz-Josef; Panten, Johannes; Pickenhagen, Wilhelm; Schatkowski, Dietmar; Bauer, Kurt; Garbe, Dorothea; Surburg, Horst (2003). "Flavors and Fragrances". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a11_141. ISBN 978-3-527-30673-2.
  4. Eshkol N, Sendovski M, Bahalul M, Katz-Ezov T, Kashi Y, Fishman A (2009). "Production of 2-phenylethanol from L-phenylalanine by a stress tolerant Saccharomyces cerevisiae strain" (PDF). Journal of Applied Microbiology. 106 (2): 534–542. doi:10.1111/j.1365-2672.2008.04023.x. PMID 19200319. Archived from the original (PDF) on 25 September 2013. Retrieved 29 April 2013.
  5. Kanth JV, Periasamy M (1991). "Selective Reduction of Carboxylic Acids into Alcohols Using NaBH and I2". Journal of Organic Chemistry. 56: 5964–5965.
  6. Lingappa, BT; Prasad, M; Lingappa, Y; Hunt, DF; Biemann, K (1969). "Phenethyl alcohol and tryptophol: Autoantibiotics produced by the fungus Candida albicans". Science. 163 (3863): 192–4. doi:10.1126/science.163.3863.192. PMID 5762768.
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