Guaiacol

Guaiacol is a naturally occurring organic compound with the formula C6H4(OH)(OCH3). This colourless aromatic oil is 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.

Preparation
Guaiacol is synthesized by the di-methylation of catechol followed by selective mono-demethylation.
 * C6H4(OH)2 +  2 (CH3O)2SO2  →  C6H4(OCH3)2  +  2 HO(CH3O)SO2


 * C6H4(OCH3)2 +  C2H5SNa   →  C6H4(OCH3)(OH)

Uses
Guaiacol is used medicinally as an expectorant, antiseptic, and local anesthetic. Guaiacol is also used in the preparation of eugenol and vanillin.