What Are Terpenes?


Terpenes belong to a class of compounds known as aromatic hydrocarbons, and they are made up of chains of linked isoprene units. Isoprene is an abundant naturally occurring molecule with the chemical formula C₅H₈, and terpenes are formed by two or more linked isoprene units. Thus, monoterpenes (C₁₀H₁₆) are formed of two isoprene units, diterpenes (C₂₀H₃₂) from four, triterpenes (C₃₀H₄₈) from six, and so on.  Terpenes are a major component of many plant resins, cannabis being no exception. Most terpenes are strong smelling and often serve the purpose of attracting pollinators or repelling predators. Furthermore, it is thought that certain tree species release terpenes, which react with atmospheric compounds to produce aerosols, which in turn encourage water vapor to form clouds. During hot weather, these trees release higher levels of terpenes, doubling cloud cover and providing a strong cooling effect.

Terpenes Found in Cannabis

Some notable terpenes contained within the cannabis plant include d-limonene, myrcene, pinene, camphene, sabinene (all monoterpenes), squalene (a triterpene), and α-humulene and caryophyllene (both sesquiterpenes, which are made up of three isoprene units and have the chemical formula C₁₅H₂₄). According to one source, cannabis contains 58 monoterpenes and 38 sesquiterpenes. Many related compounds known as terpenoids are also contained within cannabis (such as linalool and geraniol, and even cannabinoids themselves); however, for purposes of simplicity, we will focus only on the true terpenes.