Alloocimene is a volatile C10 monoterpene distinguished by its conjugated triene system, found in numerous essential oils and valued for its reactivity in polymer chemistry and potential antimicrobial roles. 

Chemical Structure and Isomers

Alloocimene (C₁₀H₁₆, MW 136.23), or 2,6-dimethyl-2,4,6-octatriene, features a linear chain with three conjugated double bonds and methyl substituents at positions 2 and 6, existing in cis/trans configurations such as (4E,6Z)-alloocimene. Its extended conjugation contributes to a sweet, floral odor and characteristic UV absorbance, with InChIKey GQVMHMFBVWSSPF-SOYUKNQTSA-N.

This molecular structure promotes polymerization and oxidative reactivity, often requiring stabilization using antioxidants such as hydroquinone.

Natural Sources and Synthesis

Alloocimene is naturally present in essential oils of various plants, including mints (e.g., Mentha citrata), bergamot, and conifer species. It is biosynthesized via the methylerythritol phosphate (MEP) pathway through the isomerization of geranyl pyrophosphate.

At the industrial level, alloocimene can be produced through flash pyrolysis or photochemical isomerization of α-pinene, followed by purification using fractional distillation under reduced pressure.