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Guaiacol

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Guaiacol
File:Guaiacol 3D.png
Names
IUPAC name 2-methoxyphenol
Other names o-Methoxyphenol; Methylcatechol
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.786 Edit this at Wikidata
KEGG
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C7H8O2/c1-9-7-5-3-2-4-6(7)8/h2-5,8H,1H3Key: LHGVFZTZFXWLCP-UHFFFAOYSA-N
  • InChI=1/C7H8O2/c1-9-7-5-3-2-4-6(7)8/h2-5,8H,1H3Key: LHGVFZTZFXWLCP-UHFFFAOYAI
SMILES
  • COc1ccccc1O
Properties
Chemical formula C7H8O2
Molar mass 124.14 g/mol
Density 1.112 g/cm, liquid
1.129 g/cm, crystals
Melting point 28 °C (82 °F; 301 K)
Boiling point 204-206 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Guaiacol is a naturally occurring organic compound with the formula C6H4(OH)(OCH3). Although it is biosynthesized by a variety of organisms, this colorless aromatic oil is usually derived from guaiacum or wood creosote. Samples darken upon exposure to air and light. Guaiacol is present in wood smoke, resulting from the pyrolysis of lignin. The compound contributes to the flavor of many compounds, e.g. roasted coffee.

Preparation

In industry, guaiacol is produced by methylation of catechol, e.g. using potash and dimethyl sulfate:

C6H4(OH)2 + (CH3O)2SO2 → C6H4(OH)(OCH3) + HO(CH3O)SO2

Laboratory methods

Guaiacol can be prepared by diverse routes in the laboratory. 2-Aminoanisole, derived in two steps from anisole, can be hydrolyzed via its diazonium derivative. Guaiacol can be synthesized by the dimethylation of catechol followed by selective mono-demethylation.

C6H4(OCH3)2 + C2H5SNa → C6H4(OCH3)(ONa) + C2H5SCH3

Uses

Guaiacol is a precursor to various flavorants such as eugenol and vanillin. Its derivatives are used medicinally as an expectorant, antiseptic, and local anesthetic. It also can be used as a dye in chemical reactions, as oxygen will turn guaiacol from colorless to brown.

Related compounds

Guaiacol carbonate is known as duotal, the phosphate as phosphatol, the phosphite as guaiaco-phosphal (phosphotal is a mixture of the phosphites of creosote phenols). The valerianic ester of guaiacol is known as geosote, the benzoic as benzosol, the salicylic as guaiacolsalol, while the glycerin ether is the drug guaifenesin. The related derivative, dimethoxybenzene or veratrole, is also useful. In preparation of food by smoking, guaiacol is the main chemical responsible for the smoky taste, whereas syringol is responsible for the smoky aroma.

Guaiacol is used as an inducer in Biochemical transformation. It has powerful effect on the fungi culture to incite them for producing the enzyme in their liquid or agar culture.

Safety

Methoxyphenols are potential biomarkers of biomass smoke exposure, e.g. from inhalation of woodsmoke. Dietary sources of methoxyphenols overwhelm the contribution from inhalational exposures to woodsmoke.

Locust pheromone

Guaiacol is produced in the gut of locusts, Schistocerca gregaria, by the breakdown of plant material. This process is undertaken by the gut bacterium Pantoea (Enterobacter) agglomerans. Guaiacol is one of the main components of the pheromones that cause locust swarming.

References

  1. Merck Index, 13th Edition, 4568.
  2. Chemindustry list of synonyms for guaiacol
  3. See for example, Duffey, S. S.; Aldrich, J. R.; Blum, M. S. (1977). "Biosynthesis of phenol and guaiacol by the hemipteran Leptoglossus phyllopus". Comparative Biochemistry and Physiology, Part B: Biochemistry & Molecular Biology. 56 (2B): 101–102. doi:10.1016/0305-0491(77)90029-3.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Dorfner, R; Ferge, T; Kettrup, A; Zimmermann, R; Yeretzian, C (2003). "Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry". Journal of agricultural and food chemistry. 51 (19): 5768–5773. doi:10.1021/jf0341767. ISSN 0021-8561. PMID 12952431. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  5. Helmut Fiege, Heinz-Werner Voges, Toshikazu Hamamoto, Sumio Umemura, Tadao Iwata, Hisaya Miki, Yasuhiro Fujita, Hans-Josef Buysch, Dorothea Garbe, Wilfried Paulus "Phenol Derivatives" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a19_313
  6. R. N. Mirrington and G. I. Feutrill (1988). "Orcinol Monomethyl Ether". Organic Syntheses; Collected Volumes, vol. 6, p. 859.
  7. C. F. H. Allen and J. W. Gates, Jr. (1955). "o-Eugenol". Organic Syntheses; Collected Volumes, vol. 3, p. 418.
  8. Esposito, Lawrence J. (1997). "Vanillin". Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition. Vol. 24. New York: John Wiley & Sons. pp. 812–825. {{cite encyclopedia}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  9. JBC Journal of Biological Chemistry
  10. PNAS, National Academy of Sciences of the United States of America
  11. CRITICAL REVIEW OF THE HEALTH EFFECTS OF WOODSMOKE
  12. Nature, Pheromones: Exploitation of gut bacteria in the locust
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