EUGENOL, an odoriferous principle, the chief constituent of oil of cloves, and occurring in many other essential oils. Structur ally it is allyl guaiacol, C10H12O2. It can be synthetically prepared by the reduction of coniferyl alcohol, which occurs in combination with glucose in the glucoside coni ferin, C16H22O8. It is a colourless oil boiling at 247° C, and having a spicy odour. By the action of alkalis it is converted into iso eugenol, which on oxidation yields vanillin, the odorous principle of vanilla (q.v.). This transformation of allyl phenols into propenyl phenols is very general. The amount of eugenol in oil of cloves can be estimated by acetylation in presence of pyridine or by absorption in normal potassium hydroxide solution in a cassia flask. Chavibetol, an isomeride of eugenol, occurs in the ethereal oil obtained from Piper betle.
The structural relations are :