What Is Guaiacol?
Guaiacol is a type of phenol with a methoxy group, whose molecular formula is C7H8O2.
It is also called 2-hydroxyanisole, methylcatechol, and o-methoxyphenol. It is also described as guaiacol or guaiacol.
Guaiacol is a natural flavor compound produced by wine aged in oak barrels. Guaiacol and 2,4,6-trichloroanisole are said to be responsible for cork rot in wine.
Uses of Guaiacol
Guaiacol is the main ingredient of creosote. Creosote is a mixture of phenols produced by distilling wood tar obtained from beech plants.
It has bactericidal and antiseptic properties and is used as an internal medicine for various types of diarrhea, intestinal fermentation, and food poisoning. It also has expectorant and antitussive effects and is used as a remedy for chronic bronchitis.
It can also be used as a synthetic raw material for fragrances due to its distinctive aromatic odor. It is also used as a regulator of vanillin, the raw material for the aroma of vanilla.
Properties of Guaiacol
Guaiacol has a melting point of 28°C and a boiling point of 204-206°C. It has a characteristic odor and is a colorless to light yellow liquid or colorless crystalline solid. It is somewhat insoluble in water and miscible in methanol and ethanol.
Because of its toxic and irritating properties, accidental contact with the mucous membranes of the mouth requires immediate rinsing. The lethal dose for adults is 3-10 g.
Guaiacol has a methoxy group at the 2-position of phenol and is also called 2-methoxyphenol. Its molecular weight is 124.13 and its specific formula is 2-CH3OC6H4OH.
Other Information on Guaiacol
1. Synthesis of Guaiacol
Guaiacol was first isolated by Otto Paul Unverdorben in 1826. Guaiacol can be synthesized by methylating o-catechol with potassium carbonate and dimethyl sulfate.
Guaiacol can be prepared in the laboratory in a variety of ways. Guaiacol is produced by the two-step hydrolysis of o-Anisidine, derived from anisole, via a diazonium derivative. Guaiacol can also be synthesized by the dimethylation of catechol and selective monodemethylation.
2. Reaction of Guaiacol
Guaiacol derived from biomass is a useful precursor for synthesizing a wide variety of compounds as “green fuels”. For example, it is used to quantify peroxidase.
Peroxidase is an enzyme that can oxidatively cleave the peroxide structure into two hydroxyl groups. In the presence of hydrogen peroxide, peroxidase produces tetraguaiacol. Tetraguaiacol is a colored compound that can be quantified by absorbance at 420-470 nm.
3. Structural Isomers of Guaiacol
The structural isomers of guaiacol that differ in the position of the substituent are 3-methoxyphenol and 4-methoxyphenol. 3-methoxyphenol has a methoxy group in position 3, while 4-methoxyphenol has a methoxy group in position 4.
3-Methoxyphenol is also called m-methoxyphenol, m-guaiacol, m-hydroxyanisole, 3-hydroxyanisole, resorcinol monomethyl ether
Mekinol, 4-hydroxyanisole, and para-guaiacol are other names for 4-methoxyphenol.