Oleum Styracis. Storaxbl. - Essence de Styrax.
Origin. The oriental storax, Liquidambar orientate, Mill. (Ger. Styraxbaum, family Hamamelidaceee), which resembles the plane and which attains a height of 30 m., is indigenous to the southern part of Asia Minor. In its cortical tissues the tree secretes a fragrant balsam which congeals to a resin-like mass when exposed to the air. It is obtained by boiling the bark with water and subsequent expression. This product constitutes the styrax liquidus of commerce. This is a tough, dirty gray or greenish-gray, resinous mass of a peculiar aromatic odor and a sharp, spicy taste.
Upon distillation with water, storax yields 0,5 p.c. of a volatile oil; when high tension steam is used, 1 p.c. and more.
Properties. Storax oil is a bright yellow to dark brown liquid with a pleasant odor. According to the style of distillation employed it varies greatly in character. If the hydrocarbons predominate, the oil is lighter than water. The presence of a larger percentage of alcohols and cinnamic acid esters causes it to sink in water. Hence the specific gravity fluctuates between 0,89 and 1,06; aD - 38° to +0°30'; nD20o1,53950 to 1,56528; A. V. 0,5 to 33; E. V. 0,5 to 130; soluble in 1 vol. of 70 p.c. alcohol, the addition of from 2 to 5 vol. generally causing opalescence; soluble in all proportions of 80 p.c. alcohol, but in this case also the dilute solution mostly shows opalescence. Oils with a higher ester-number are less readily soluble.
Composition. The peculiar odor of storax oil which reminds one somewhat of paraffin oil is due to its styrene1) content.
Styrene or phenylethylene C6H6CH:Ch2 boils at 146°, is optically inactive and can be identified by its dibromide C6H5-Chbr-CH2Br which melts at 74°. (Comp. vol. I, p. 281).
According to van 't Hoff2), the optical rotation of oil of storax is due to the presence of a substance C10H16O or C10H18O called styrocamphene.
1) E. Simon, Liebigs Annalen 31 (1839), 265. 2) Berl. Berichte 9 (1876), 5.
Upon distillation of the storax, a part of the more or less volatile cinnamic acid esters, viz., of ethyl1), benzyl2), phenyl-propyl, and of cinnamyl alcohols (styracin), also their alcoholic components, principally phenylpropyl alcohol and cinnamyl alcohol, further vanillin3) pass over in part into the oil.
An investigation of storax by A. Tschirch and L. van Itallie4) verified the statements made by von Miller and by K. Dieterich.
From an oil of storax bark H. von Soden and W. Rojahn5) isolated naphthalene (m. p. 79°).
Adulteration. Two oils that had been greatly adulterated have been examined by Schimmel& Co.0) They possessed the following properties:
1. d15o1,0986; aD - 1°55'; nD20o1,56149; A.V.0,5; E.V. 239,9; soluble in 2 vol. of 80 p.c. alcohol forming an opalescent solution.
2. d15o0,8731; aD +19°20'; nD20oJ,47763; A.V. 0,1; E.V.5,0; soluble in 5 to 6 vol. of 90 p.c. alcohol to a turbid solution.
The first oil was suspicious because of its high specific gravity and the high ester value at once indicated adulteration. A more careful examination revealed the fact that the oil was nothing more nor less than benzyl benzoate perfumed with styrene. When fractionated under 4 mm. pressure it yielded 5 p.c. of a first fraction that distilled over between 35 and 40°, whereas 90 p.c. of the oil came over between 156 and 157°. The latter showed the constants of benzyl benzoate; d15o1,1246; nD20o1,57000; congealing point +18,1°; E.V. 262,3.
The second oil had a very low specific gravity; the index of refraction was too low and the dextro-rotation correspondingly too high. The suspicion that this oil also was adulterated was confirmed by its boiling temperatures. Upon fractionation about 45 p.c. passed over between 156 and 160° (757 mm.). This fraction consisted of a-pinene (d15o0,8668; aD+21°33'; nD20° 1.47225; m.p. of pinene nitrolbenzylamine 121,5°). Inasmuch as this hydrocarbon has heretofore not been found in storax oil and since larger amounts thereof cannot be contained in genuine oil it follows without doubt that the oil in question was grossly adulterated with turpentine oil.
1) W. von Miller, Liebig's Annalen 18S (1877), 184.
2) A. Laubenheimer, ibidem 164 (1872), 289.
3) K. Dieterich, Pharm. Zentralh. 37 (1896), 425.
4) Arch, der Pharm. 239 (1901), 506. 5) Pharm. Ztg. 47 (1902), 779.
6) Report of Schimmel & Co. April 1910, 101.