Alphatransfarnesene

Alpha‑trans‑farnesene is a sesquiterpene hydrocarbon with the formula C15H24. It is a clear, colorless liquid that readily vaporises and is characterised by a sweet, floral odour. The compound is one member of the farnesene family, which also includes the more common cis‑ and trans‑α‑farnesene isomers. Chemically, the molecule consists of a 15‑carbon chain containing three conjugated double bonds.

The compound is produced naturally in many higher plants, most notably in apple trees, pine species, apple–scented ornamental plants, as well as in tea, basil and other aromatic herbs. In flowers and fruits it serves as a volatile organic compound (VOC) involved in pollinator attraction and in plant–plant communication. Additionally, alpha‑trans‑farnesene has been documented as an antifeedant for certain insect herbivores and as an allergen for sensitive individuals.

Biosynthetically, alpha‑trans‑farnesene is derived from farnesyl pyrophosphate (FPP) via the action of a specific α‑farnesene synthase enzyme. The enantiomeric form is produced by the rotation around the C9–C10 bond, giving the thermodynamically stable trans configuration. Once released into the atmosphere, the compound can undergo rapid oxidation, forming a range of terpene‑derived derivatives.

The chemical’s commercial uses include application as a flavour or fragrance additive in cosmetics, food, and perfumery. Its insecticidal and repellent properties have prompted research into its potential as a biopesticide and for bio‑insect deterrent formulations. Because of its volatile nature, it is also studied in atmospheric chemistry and as a source of renewable terpene feedstock for industrial uses.