Anethole (or trans-anethole) is an aromatic compound that accounts for the distinctive “licorice” flavor of anise, fennel, star anise, and anise myrtle. It may also be referred to as p-propenylanisole, anise camphor, isoestragole, or oil of aniseed. It is unrelated to glycyrrhizic acid, the compound which makes licorice taste sweet. The full chemical name is trans-1-methoxy-4-(prop-1-enyl)benzene. The chemical structure is shown at right. Chemically, an aromatic, unsaturated ether.

Anethole appears as white crystals at room temperature. Its melting point is 21 °C, and its boiling point is 234 °C. It has a chemical formula of C₁₀H₁₂O, and is closely related to estragole, an aromatic compound found in tarragon and basil.

Anethole is distinctly sweet as well as having its flavoring properties and is measured to be 13 times sweeter than sugar. It is perceived as being pleasant to the taste even at higher concentrations.

It is slightly toxic and may act as an irritant in large quantities. It can stimulate hepatic regeneration in rats, and can also produce spasmolytic activity in high doses. It is a chemical precursor for paramethoxyamphetamine (PMA), which has been sold as ecstasy resulting in several deaths.

• Anisole, the compound without the propenyl group
• Estragole, a double bond isomer

• Safety (MSDS) data for anethole
• Molecular Models from OUC: anethole
• Seattle Weely: Ask Dr. Food: All About Trans-Anethole

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