Guaiacol (GCL)

Guaiacol is a naturally occurring organic compound with the formula C6H4(OH)(OCH3), discovered by Ascanio Sobrero. Although it is biosynthesized by a variety of organisms, this yellowish 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. Guaiacol carbonate is known as duotal, the phosphate as phosphatol, the phosphite as guaiaco-phosphal.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.