Eucalyptol.

C₁₀H₁₈O = 154.144.
Synonyms.—Cineol; Cajuputol.

Eucalyptol, C₁₀H₁₈O, is obtained chiefly from oil of eucalyptus, but also occurs in oil of cajuput and other oils. It is official in the U.S.P. It occurs as a colourless liquid with a characteristic aromatic camphoraceous odour, and a pungent, spicy, and cooling taste. Specific gravity, 0.930 (0.925 at 25°). Boiling-point, 176° to 177°. Refractive index, 1.4559. Optically inactive. When placed in a freezing mixture it solidifies to a mass of colourless crystals, which, when pure, melt again at -1°. It forms a solid compound with resorcin, and yields characteristic loose addition products with bromine, hydrochloric acid, hydrobromic acid and phosphoric acid. If a portion be shaken with an equal volume of sodium hydroxide solution it should not decrease in bulk; its alcoholic solution should be neutral to test paper, and should not assume a brownish or violet colour on the addition of a drop of ferric chloride solution (absence of phenols). If 1 mil of phosphoric acid be gradually added to 1 mil of eucalyptol placed in a freezing mixture, a solid white crystalline mass of cineol-phosphoric acid should be obtained, from which cineol should separate on the addition of warm water. A less pure substance obtained by simple fractionation of oil of eucalyptus is also sold as eucalyptol. This will not solidify entirely on cooling to about -5°. It has a specific gravity from 0.90 to 0.915, and is optically active. Eucalyptol should be preserved in well-stoppered bottles, protected from the light.

Miscible in all proportions with alcohol, carbon bisulphide, and glacial acetic acid.

Action and Uses.—Eucalyptol has a similar action to that of oil of eucalyptus, to which it is to be preferred, both for internal administration and for inhalation. For internal use capsules are prepared, containing 6 or 12 centimils (0.06 or 0.12 milliliters) (1 or 2 minims). Inhaled from hot water or from an oro-nasal inhaler, it is less irritating, and in the latter method more completely volatilisable, than oil of eucalyptus. Oily spray solutions contain from 1 part in 30 to 1 in 16, with liquid paraffin.

Dose.—½ to 3 decimils (0.05 to 0.3 milliliters) (1 to 5 minims).

PREPARATIONS.

Nebula Eucalyptolis Composita, B.P.C.—COMPOUND EUCALYPTOL SPRAY. Syn.—Nebulol Thymolis Composita.

Eucalyptol, 8; camphor, 2; menthol, 2; thymol, 0.11; liquid paraffin, to 100.

Parogenum Eucalyptolis, B.P.C.—EUCALYPTOL PAROGEN. Syn.—Eucalyptol Vasoliment. 1 in 5.

An antiseptic and mildly rubefacient application for use in chronic rheumatic affections.

Pastillus Eucalyptolis, B.P.C.—EUCALYPTOL PASTILLE. ½ minim.

Pastillus Eucalyptolis et Cocainae, B.P.C.—EUCALYPTOL AND COCAINE PASTILLE.

Eucalyptol, ½ minim; cocaine hydrochloride, 1/20 grain.

The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.