Isoeugenol is a phenylpropene, a propenyl-substituted quaiacol. A phenylpropanoid, it occurs in the essential oils of plants such as ylang-ylang (Cananga odorata). It can be synthesized from eugenol and had been used in the manufacture of vanillin. It may occur as either the cis (Z) or trans (E) isomer. Trans (E) isoeugenol is crystalline while cis (Z) isoeugenol is a liquid.