12. Anise ketone. According to Tardy1), staranise oil con-tains a substance C6H4<H J,n „H (b.p. 263; d 1,095) which he designated anise ketone (acetone anisique), the oxime of which melts at 72° and the semicarbazone at 182°. Anise ketone combines with bisulphite, and upon oxidation with faintly alkaline permanganate solution yields acetic acid and anisic acid.
1) Tardy, Etude analytique sur quelques essences du genre anisique. These Paris (1902), p. 22; Report of Schimmel & Co. October 1902, 79.
2) Report of Schimmel & Co. October 1895, 7.
3) Arch, der Pharm. 229 (1891), 86.
4) Report of Schimmel & Co. April 1910, 101.
13. The highest boiling fraction consists of a sesquiterpene: b. p. 272 to 275°; aD 501).
Two other substances should be mentioned which result upon exposure to air and which are always found in staranise oil as in every anethol-containing oil, viz., anisic aldehyde and anisic acid. The older the oil, the more it contains of these substances.
Properties. Staranise oil is a colorless or yellowish, strongly refractive liquid which congeals in the cold because of its anethol content. Its odor is anise-like and its taste intensely sweet. d20o0,98 to 0,99; aD slightly la?vogyrate to - 2°, in isolated cases slightly dextrogyrate2) to + 0°36'; nD20o 1,553 to 1,556; congealing point +15 to +18°, mostly about +16°, in exceptional cases it drops to +14°3); soluble in 1,5 to 3 vol. and more of 90 p. c. alcohol.
Under certain conditions, more particularly when cooled slowly in sealed vessels, staranise oil can be cooled much below its congealing point without solidifying and it then acquires the property of remaining liquid for a long time. The congealing is usually started by some external stimulus, e. g. by a particle of dust or by some disturbance. It then takes place all the more quickly the more sub-cooled the oil was at the time. Most readily, however, such a sub-cooled oil is made to congeal by introducing a fragment of solid anethol or by scratching the inner wall of the container with a glass rod.
1) Foot noote 1, p. 385.
2) The dextro-rotation probably results from the admixture of the dextrogyrate leaf oils (see p. 390).
3) From time to time there appear in the market oils which, though they have a lower congealing point, are nevertheless unadulterated. The properties of five such oils were: d15° 0,988 to 0,998; aD+0o11 to +0°32'; cong.pt. + 8,75 to 13,75°; all soluble in 1,5 vol. of 90 p.c. alcohol. These oils, which are designated flower oils, are not distilled from the flowers as the name would indicate but from the unripe fruits. In order to facilitate the ripening of the remaining fruits, these are picked. Possibly these oils are nothing more or less than staranise leaf oils (see p. 390). It goes without saying that such "flower" oils are of inferior value and should be sold as staranise oil (Report of Schimmel & Co. October 1898, 42).
It is noteworthy that an oil which has been kept in half-filled bottles for a considerable time or which has been liquefied repeatedly in the presence of air, loses its capacity to congeal. This is due to the partial change of anethol to anisic aldehyde and anisic acid.
In order to distinguish staranise oil from anise oil, a color reaction1) with alcoholic hydrogen chloride has been recommended. However, it does not yield reliable results. With this reagent staranise oil is said to give a yellowish to brownish color, whereas anise oil is colored blue or red according to the degree of concentration of the hydrochloric acid.
Examination. For the detection of adulterations and in order to ascertain the presence of a normal anethol content, the determination of the specific gravity, solubility and congealing point are necessary.
Formerly adulterations were never observed. Occasionally, however, it occurs to the Chinese to add petroleum or some other mineral or fatty oil2). These cause a reduction of the specific gravity and congealing point. They also interfere with the solubility of the oil in 90 p. c. alcohol. Whereas a pure oil yields a perfect solution with 3 vol. of 90 p.c. alcohol which remains clear upon the addition of more alcohol, an oil adulterated with petroleum yields only turbid mixtures, from which drops of petroleum separate upon standing.
In order to isolate the petroleum, the oil is distilled with water vapor, the first fraction collected separately and treated with concentrated sulphuric acid, then with strong nitric acid. The volatile oil is destroyed when subjected to such treatment whereas the petroleum remains almost unchanged and can be recognized by its general behavior. High-boiling mineral oils are not volatile with water vapor, hence must be looked for in the residue.
1) Eykman, Mitteil. d. deutsch. Gesellsch. f. Natur- und Volkerkunde Ostasiens. 23 (1881). - ). C. Umney, Pharmaceutical Journ. III. 19 (1889), 647. - P. W. Squire, ibidem III. 24 (1893), 104. - Umney, ibidem III. 25 (1894/95), 947.
2) Report of Schimmel & Co. October 1912, 104.
In how far the properties of staranise oil are modified by an addition of from 5 to 10 p. c. of petroleum is indicated in the following table1):
Solubility in 90 p. c. alcohol
Pure oil .....................
1: 2,2 and more
The same with 5 % peThe same with 10 °/o petroleum ....
+ 16°,25 + 14°,75
not clearly soluble in 10 vol. of 90 p. c. alcohol
From the above data it becomes evident that the adulteration of staranise oil with petroleum is more readily recognized by means of the specific gravity and solubility than by the congealing point. Hence it should invariably be demanded that an oil respond to the requirements specified under "Properties" as regards its solubility and specific gravity, even though the congealing point be satisfactory.
Occasionally oils have been observed, the low anethol content of which seemed to indicate adulteration. It was supposed2) that a camphor oil fraction had been added. Comparative experiments3), however, revealed the fact that oils of the same properties as the suspected ones are obtained when normal staranise oil is deprived of part of its anethol by freezing.