Guaiacol

Phenols & Ethers Flavors & Fragrances Pharma

Guaiacol (2-methoxyphenol, o-methoxyphenol, methylcatechol, o-hydroxyanisole) is the monomethyl ether of catechol, a colorless to pale yellow oily liquid or low-melting crystal at room temperature with a characteristic smoky, spicy, and herbal aroma. It is a widely used phenol-ether fine chemical with combined preservative, antibacterial, and fixative functions. The product is slightly soluble in water, readily soluble in ethanol, ether, chloroform, and sodium hydroxide solution, with a melting point of 26-29℃ and a boiling point of 204-206℃, and can meet both food-grade and pharmaceutical-grade standards.

Guaiacol can be prepared by reacting catechol with a methylating agent such as dimethyl sulfate under alkaline conditions, or by diazotization and hydrolysis of o-anisidine; it also occurs naturally in wood tar and guaiac resin and can be obtained by extraction and separation. The phenolic hydroxyl group is weakly acidic and can undergo salt formation, etherification, and esterification; the methoxy group acts as an ortho/para director for electrophilic substitution on the ring, providing a convenient route for constructing various polysubstituted benzene-ring derivatives. The product readily oxidizes and discolors in air and must be stored sealed away from light.

Applications: Key intermediate for vanillin and eugenol synthesis; pharmaceutical expectorant intermediate.