Terpinene

Terpinene refers to a group of monoterpene hydrocarbons with the molecular formula C10H16. They are isomeric hydrocarbons derived from the p-menthane (cymene) skeleton and are distinguished by two carbon–carbon double bonds in different positions. The principal isomers are alpha-terpinene, beta-terpinene, gamma-terpinene, and delta-terpinene. These compounds occur naturally in many essential oils and contribute to the characteristic aromas of citrus, herbs, and pine resins. Alpha- and gamma-terpinene are among the more abundant terpinene isomers found in essential oils such as orange, cumin, and oregano oils, while beta- and delta-terpinene also appear in various plant sources.

In terms of chemistry, terpenes of this class are unsaturated hydrocarbons and volatile liquids at room temperature. They can be oxidized or hydroxylated to form oxygenated derivatives such as terpineols and related compounds, which are often used as fragrance ingredients or scent notes. Terpinene and its oxygenated products serve as intermediates in the biosynthesis and industrial production of a broad range of terpenoids.

Applications include use as fragrance and flavor components, in perfumery and cosmetics, and as intermediates in the synthesis of other monoterpenes. Safety profiles are generally guided by typical essential-oil constituents; concentrations and regulatory status vary by jurisdiction.