Eucalyptol (U. S. P.)—Eucalyptol.
Related entry: Eucalyptus (U. S. P).—Eucalyptus
FORMULA: C10H18O. MOLECULAR WEIGHT: 153.66.
"A neutral body obtained from the volatile oil of Eucalyptus globulus, Labilladière, and of some other species of Eucalyptus (Nat. Ord.—Myrtaceae). Eucalyptol should be kept in well-stoppered bottles, in a cool place, protected from light"—(U. S. P.).
SYNONYMS: Cineol, Cajuputol.
Preparation and History.—In preparing the oil of eucalyptus from eucalyptus leaves, that portion distilling between 170° C. (338° F.) and 178° C. (352.4° F.), is called crude eucalyptol. It maybe purified by surrounding the crude eucalyptol by a refrigerating mixture, when eucalyptol separates in long, needle-like, colorless crystals. The crystals are then drained from their adherent oil, and the process of crystallizing is repeated several times. Eucalyptol may be obtained from other oils as well as from those of the various species of Eucalyptus (see Amer. Jour. Pharm., 1889, p.371). Thus it forms a constituent part of oils of cajuput and of rosemary, and is particularly abundant in the Oil of Santonica, from Artemisia pauciflora, Weber, which, in fact, is almost wholly composed of eucalyptol. Wallach and Brass, in 1884, prepared it from the latter oil by forming a crystalline compound with gaseous hydrochloric acid, pressing off the mother-liquor, liberating the eucalyptol with water, purifying with caustic potash in warm alcoholic solution, and finally drying and rectifying the oil. According to Schimmel's Report (April, 1891), eucalyptus oil from E. oleosa is also rich in eucalyptol, solidifying when put into a freezing mixture. Jahns, in 1885, found eucalyptol to possess the formula C10H18O, and to be identical with cineol, a substance obtained by Wallach and Brass, in 1884, from oleum cynae, and found in turn to be identical with cajuputol, from oil of cajuput.
In 1895, Mr. Scammell, in Adelaide (Australia), took out a patent for the preparation of eucalyptol from oil of eucalyptus, the process consisting in the formation of a crystalline compound of phosphoric acid with eucalyptol, decomposable afterward by water into its constituents (Pharm. Centralh., 1895, p. 419). A crystallizable acid may be produced by acting upon eucalyptol with nitric acid, while phosphoric anhydride (P2O5. converts it into eucalyptene (C10H18), and eucalyptolen.
Description and Tests.—"A colorless liquid, having a characteristic, aromatic, and distinctly camphoraceous odor, and a pungent, spicy, and cooling taste. Specific gravity, 0.930 at 15° C. (59° F.). Boiling point, 176° to 177° C. (348.8° to 350.6° F.). It is optically inactive (distinction from the oil of eucalyptus and many other volatile oils). When exposed to a temperature some degrees below 0° C. (32° F.), or placed in a freezing mixture, it solidifies to a mass of colorless, needle-shaped crystals, which liquefy at -1° C. (30.2° F.). Soluble, in all proportions, in alcohol, carbon disulphide, and glacial acetic acid. If a portion of eucalyptol be shaken with an equal volume of sodium hydrate T.S., it should not diminish in volume. Its alcoholic solution should be neutral to litmus paper, and should not assume a brownish or violet color on the addition of a drop of ferric chloride T.S. (absence of phenols)"—(U. S. P.).
Action, Medical Uses, and Dosage.—(Same as Eucalyptus, which see).