Clove Leaf Oil

#### Clove Leaf Oil. From the whole leaves and twigs of the clove tree (see **Clove**** ****Bud**** ****Oil**, previous monograph), an essential oil is distilled in the clove growing areas of northeastern Madagascar. The distillation is a so-called "direct-fire" distillation and corresponds to a type of water-distillation. The stills are mostly of an extremely primitive kind. Almost inevitably a certain amount of clove stems are found among the leaves and twigs, but the stems will obviously appear only during and right after the clove bud harvest (there is only one bud harvest per year in Madagascar). It is estimated that, out of Madagascar's annual 1000 metric ton-production of clove oil, about 80% is derived from leaf material and 20% from clove stems. The oil is usually bulked, but lots of oil of high eugenol content, sold separately, may derive from distillation of "high- stem- content" material. Clove leaf oil is not produced outside of Madagascar, but production can be expected in the near future from the Comoro islands where extensive plantings of young clove trees (seedlings from Madagascar) are growing up since 1952. When crude and natural, **Clove Leaf Oil **is a dark brown, often violet- or purple-brown oil which may show some precipitate or cloudiness. Madagascan-French bulk-producers make an effort to strain and dehydrate the oil before it is exported, and they usually obtain oils with very high eugenol content. The crude oil is usually rectified (steam distilled or vacuum-distilled) in Europe or in the U.S.A. before it is used in perfumes or flavors. However, the major part of all clove leaf oil is used in the chemical industry for the isolation of eugenol of which the oil contains 82 to 88%. The oil also contains significant amounts of the sesquiterpene Caryphyllene which is isolated during the production of eugenol. **Caryophyllene **finds some use in perfumery, particularly in the reproduction of certain essential oils, e.g. cubeb oil, black pepper oil, etc. (skilful adulteration!). More recently, caryophyllene has been used as a starting material in the production of new and interesting perfume materials, e.g. certain related ketones, etc. Neither eugenol nor caryophyllene have yet been produced synthetically on a commercial scale. The odor of crude clove leaf oil is somewhat harsh, phenolic, only slightly sweet, with a "burnt" breadlike note, and distinctly different from the odor of eugenol, and different also from the odor of clove bud oil. Woodiness and dryness probably are the most typical notes of clove leaf oil. Rectified (sometimes called redistilled) clove leaf oil is pale yellow and clear; it smells sweeter than the crude oil, less harsh and burnt, but still somewhat dry-woody. The odor is much closer to that of eugenol. Rectified clove leaf oil may find use in all types of spicy perfumes, particularly in "low-cost" types and soap perfumes. In the case of the latter, however, the risk of discoloration at higher concentrations should be kept in mind. Alkali will produce a brown, iron and purple- violet discoloration in the presence of significant amounts of clove oils. On the other hand, only eugenol itself gives the typical spice odor. None of the non-phenolic derivatives (methyl eugenol, aceteugenol, etc.) will produce a similar spicyness in a perfume. Thus, there is no substitute for clove oil or eugenol, if the hydroxyl group (—OH group) is occupied or "inactivated" in the eugenol molecule. Accordingly, there are no stable white soaps containing significant amounts of eugenol or clove oil on the market. Spicy smelling soaps are usually colored dark amber or brown ("Windsor", etc.), whereby the discoloration is camouflaged. In flavor work, the clove bud oil and, occasionally, the absolute from clove buds are preferred since these products reproduce the true clove flavor to a higher degree, and they are far more than being merely "eugenol"-flavor materials. The **Minimum Perceptible of **clove leaf oil (crude) is only one-third of the figure for a high-grade clove bud oil. The flavor type of the crude leaf oil is, however, inacceptable for use in foods. It does not reproduce the flavor of the clove bud such as it is known by many consumers. The apparent power in the clove leaf oil flavor is probably derived from traces of lower aldehydes, furfural, etc. which are often present in essential oils from leaves and other green plant material. The isolated eugenol from clove leaf oil is used in pharmaceutical and dental preparations, in the synthesis of vanillin, for the production of eugenol derivatives, etc. Eugenol is not produced synthetically on a commercial scale, and clove leaf oil is the cheapest starting material for the isolation of this important aromatic chemical. The switch to "lignin-vanillin" during recent years has caused decrease in the clove leaf oil price, and the oil is now (in 1959/60) hardly profitable to produce. A series of devastating cyclones in March, 1959 on the Madagascan east coast destroyed portions of the clove plantations, and this caused a temporary increase in the price of the leaf oil. In respect to quantity produced, **Clove**** ****Leaf**** ****Oil**** **ranks among the 12 largest essential oils in the world.