Guaiacol is an agent thought to have disinfectant properties and used as an expectorant. Guaiacol is produced when the lignin found in wood is burned, and it’s partly responsible for the flavour of smoke-preserved food such as bacon and fish, as well as peated whisky and roast coffee. Although guaiacol is the main chemical responsible for smoky tastes, wood smoke contains a wide range of compounds which can be condensed out to form ‘liquid smoke’, and used as a preservsative and flavor additive. Guaiacol can be found in some common household items like: Whisky, Kippers, Bacon, Hot Dogs, Coffee, Creosote & Couch Syrup.
Guaiacol is a precursor to various flavorants, such as eugenol & vanillin. An estimated 85% of the worlds supply of vanillin comes from guaiacol. The route entails condensation of glyoxylic acid with guaiacol to give mandelic acid, which is oxidized to produce a phenylglyoxylic acid. This acid undergoes a decarboxylation to afford vanillin.
Many plants synthesise guaiacol, and it’s often derived from plants of the genus Guaiacum. Insects such as locust, produce guaiacol in the gut to break down plant matter.
Its derivatives are used medicinally as an expectorant, antiseptic, and local anesthetic. Guaiacol is used in traditional dental pulp sedation, and has the property of inducing cell proliferation; guaiacol is a potent scavenger of reactive oxygen radicals and its radical scavenging activity may be associated with its effect on cell proliferation.