Eucalyptus Citriodora Oil

#### Eucalyptus Citriodora. Although scarcely yet in the 100-tons-per-year class, the essential oil from the leaves of **Eucalyptus**** ****Citriodora**** **has become one of the most interesting eucalyptus oils. Like all other eucalyptus species, the citriodora is originally from Australia. The tree gives a very good and useful lumber and is therefore popular in the tropics. Today, it is cultivated—and also grows wild from old plantings—in Brazil, Belgian Congo, the Seychelles, the Union of South Africa, Southern Rhodesia, Tanganyika, Indonesia, Morocco, the U.S.S.R. and Guatemala. The aforementioned countries are listed approximately in order of importance as producers of the oil. Brazil has produced 50 to 80 metric tons per year lately, while Belgian Congo turns out 10 to 15 tons. However, the all-time low in citronella oil prices during 1958—1959 has been quite detrimental to the further development of citriodora distillation in the Belgian Congo and other areas. Brazil is a large country with sizeable needs for perfumery materials, and they can probably maintain their production for local consumption in perfumes and menthol-syntheses. Steam distilled on local, but often quite modern stills, the oil is a colorless to pale yellow, mobile liquid which has a strong and very fresh, rosy- citronella-like odor and a sweet, balsamic-floral dryout note. As a source of natural citronellal, it is unsurpassed. The very high content of this oil in the best of the Belgian Congo oils (up to 82% in natural oils), and the fact that the balance consists of foreruns of a pleasant odor (light monoterpenes) and short tail fractions of geranyl acetate, etc. makes isolation of a high-grade citronellal from this oil a very attractive operation. During the shortage of Fareastern citronella oils in the early 1950's, citriodora came into the limelight and its production increased tremendously. A large European company based their entire Brazilian menthol production upon locally distilled citriodora oil. By itself, eucalyptus citriodora oil is not much used in perfumery although it offers very attractive notes for low-cost soap perfumes, soap flakes, detergents, sprays, etc. This can be due to several facts: - the oil was "reserved" for many years for the menthol producers; 2) citronellal is not very stable in soaps or alkaline medium; 3) the really large soap manufacturers might hesitate to introduce this oil in their perfumes for detergents or soap flakes because they might be unable to get sufficient quantities of the oil (if it forms a major part of the fragrance, by weight). Furthermore, they generally try to avoid using large quantities of raw materials from countries over whose future development they have little or no "control"; 4) citriodora oil will, in many other cases, be only a minor ingredient in a soap perfume as a freshener, "lifter", etc. **Eucalyptus Citriodora Oil **also serves as a starting material for the production of certain acetone-condensation products; the isolated citronellal is further processed to an excellent grade of hydroxycitronellal. The citronellal can be reduced with hydrogen in the presence of a catalyst. Various "special rose-alcohols" are produced by similar methods. The 1960's will tell us about the future of citriodora oil, but it is obvious that Congo and Brazil producers are uninterested in producing, let alone exporting, this oil at the same price as Formosa citronella oil (1959 price fell below 8/— sh. engl. per kilo for oils of less than 45% aldehyde content!). This kind of competition is not exactly conducive towards improving the level of living among the native producers or the settlers in the growing areas. At the present price level, it is hardly possible to adulterate the essential oil of **Eucalyptus Citriodora **at all. Even "synthetic" citronellal (from American turpentine) would be too expensive to use as a "cutting" agent. Belgian Congo citriodora oils have usually shown the highest citronellal content (over 80% in oils from the Ituri district) and superior overall quality.