Guaiacol
Guaiacol[1] | |
---|---|
2-methoxyphenol | |
Other names o-Methoxyphenol; Methylcatechol[2] | |
style="background: #F8EABA; text-align: center;" colspan="2" | Identifiers | |
CAS number | 90-05-1 |
PubChem | 460 |
ChemSpider | 447 |
SMILES | Script error: No such module "collapsible list". |
style="background: #F8EABA; text-align: center;" colspan="2" | Properties | |
Molecular formula | C7H8O2 |
Molar mass | 124.14 g/mol |
Density | 1.112 g/cm3, liquid 1.129 g/cm3, crystals |
Melting point |
28 °C, 301 K, 82 °F |
Boiling point |
204-206 °C |
(what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Infobox references |
Guaiacol is a naturally occurring organic compound with the formula C6H4(OH)(OCH3). Although it is biosynthesized by a variety of organisms,[3] 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.[4]
Preparation
Guaiacol is produced industrially by methylation of catechol, e.g. using potash and dimethyl sulfate:[5]
- 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.[6]
- C6H4(OCH3)2 + C2H5SNa → C6H4(OCH3)(ONa) + C2H5SCH3
Uses
Guaiacol is a precursor to various flavorants such as eugenol[7] and vanillin.[8] 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).[citation needed] 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.
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. [9]
References
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de:Guajacol fr:Gaïacol it:Guaiacolo hu:Gvajakol nl:Guaiacol ja:グアイアコール pl:Gwajakol pt:Guaiacol ru:Гваякол
zh:愈创木酚- ↑ Merck Index, 13th Edition, 4568.
- ↑ Chemindustry list of synonyms for guaiacol
- ↑ 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.
- ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
- ↑ 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
- ↑ R. N. Mirrington and G. I. Feutrill (1988), "Orcinol Monomethyl Ether", Org. Synth.; Coll. Vol., 6: 859 Missing or empty
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(help) - ↑ C. F. H. Allen and J. W. Gates, Jr. (1955), "o-Eugenol", Org. Synth.; Coll. Vol., 3: 418 Missing or empty
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(help) - ↑ Esposito, Lawrence J.; K. Formanek, G. Kientz, F. Mauger, V. Maureaux, G. Robert, and F. Truchet (1997). "Vanillin". Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition. 24. New York: John Wiley & Sons. pp. 812–825.
- ↑ CRITICAL REVIEW OF THE HEALTH EFFECTS OF WOODSMOKE available at: http://ehs.sph.berkeley.edu/krsmith/publications/2005%20pubs/HC%20woodsmoke%20report%20Mar%2031%2005%20%28rev%29.pdf
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