The same investigators also discovered the unstable compound C9H8On03h mentioned above, which results upon the addition of nitric acid to cinnamic aldehyde in the cold and which is characterized by its crystallization capacity.
Of other investigations of the same period those of Mulder3) and Bertagnini4) should be mentioned.
Bertagnini studied the addition products of the acid sulphites of alkalies to cinnamic aldehyde, the exact composition of which was later ascertained by F. Heusler5).
The properties and derivatives of cinnamic aldehyde have been described in Vol. I, p. 424.
1) Liebig's Annalen 7 (1833), 164.
2) Ann. de Chim. et Phys. 57 (1834), 305; Liebig's Annalen 12 (1834), 24; 13 (1835), 76; 14 (1835), 50.
3) Liebig's Annalen M (1840), 147. - Journ. f. prakt. Chem. 15 (1838), 307; 17 (1839), 303 and IS (1839), 385.
4) Liebig's Annalen 85 (1853), 271. 5) Berl. Berichte 24 (1891), 1805.
The "Cass/a stearoptene" is a crystalline substance which was discovered jointly by F. Rochleder, H. Hlasiwetz and R. Schwarz1). It is observed but rarely, separating from old oils. Its constitution was determined in 1895 by ). Bertram and R. Kursten2). The stearoptene that served as a basis for this investigation had separated from the last fractions in the rectification of a cassia oil. In the pure state it consists of well-developed six-sided yellow plates that melt at 45 to 46° and have a very persistent but not very pleasant odor. This substance is identical with methyl-ortho-cumaric aldehyde a substance that can be obtained synthetically by condensation of methyl salicylic aldehyde and acetaldehyde.
Cinnamyl acetate, which was discovered in 1889 by Schimmel & Co.3), is essential but exerts no favorable influence on either odor or taste of the cassia oil. It boils between.135 and 140° (11 mm.) and possesses a rather unpleasant odor and a grating taste.
In addition to this ester there appears to be present a small amount of another, viz., the acetate of phenylpropyl alcohol. Its presence has been inferred from the boiling point of an alcohol that accompanies the cinnamyl alcohol after saponification.
On account of the ease with which cinnamic aldehyde oxidizes, oil of cinnamon always contains cinnamic acid; however, the amount, about 1 p.c.4), is less than might be assumed from the changeability of the pure aldehyde.
1) Rochleder and Schwarz, Ber. d. Academ. d. Wissensch. zu Wien, mathem. phys. Kl., June 1850, 1. Ibidem vol. 12, 190 to 199; Pharm. Zentralbl., 1831, 46; 1854, 701.
2) Journ. f. prakt. Chem. II. 51 (1895), 316.
3) Schimmel's Bericht October 1889, 19.
4) Apparently the cinnamyl acetate acts as a preservative to a high degree. A very old cassia oil, containing 77,7 p.c. of aldehyde, was exposed or a year in a shallow dish, covered with perforated filter paper, in a place where warmth, light and air had free access. After the expiration of this time, the cinnamic acid content, which in the original oil had amounted to 0,7 p.c, had increased to 8,5 p.c. A real resinification had not taken place, for the distillation residue (see under Examination) was but little greater at the end of this period than at the beginning. Under like conditions, pure cinnamic aldehyde would soon have been changed to lumps of cinnamic acid. (Report of Schimmel & Co. October 1890, 16.)
Free cinnamic acid has the undesirable property of attacking the lead of the canisters in which the oil is shipped, thus imparting to the oil a decided lead content. A crystalline sediment observed by Hirschsohn1) in a cassia oil consisted of lead cin-namate. Following up this observation with the examination of 12 commercial oils, he found that 11 of these contained lead. The detection of the lead is accomplished by shaking a few drops of the oil with hydrogen sulphide water. According to the lead content the oil is colored red to black.
If cassia oil is used for medicinal or culinary purposes, the lead-free, rectified oil only should be used.
Adulterations and their Detection. Formerly cassia oil was adulterated only with fatty oils, cedarwood oil and gurjun balsam oil. The detection of these adulterants was very simple since they lowered the specific gravity and interfered with the solubility in 80 p.c. alcohol. Because of their decided laevorotation, cedar-wood oil and gurjun balsam oil could readily be detected by means of the polariscope. Less simple was the recognition of an adulteration, practiced extensively in Macao and Hongkong toward the close of the eighties. It consisted in the addition of colophony and petroleum. At first the Chinese may have used colophony only. But, inasmuch as larger additions of rosin made the oil too thick and also increased the specific gravity, this fault was corrected with the aid of petroleum. Since this mode of adulteration did not alter the specific gravity or, remarkable though it may seem, the solubility in 80 p.c. alcohol, it remained undetected for some time. Detection was brought about only when the additions of rosin gradually became too great. The commercial oils of that period had an exceedingly unpleasant odor, a dark brown color, and a thick, varnish-like consistence. The slightly sweetish taste soon gave way to a nauseating, persistent grating sensation in the mouth. Upon rectification with water vapor, as much as 40 p.c. of a hard resinous mass remained in the still. The distillate separated in the Florentine flask in two layers: one sank under water, the other floated. The latter consisted of petroleum, as was shown upon examination.
1) Pharm. Zeitschr. f. Russland 30 (1891), 790.
The desirability of being able to detect this mode of adulteration rapidly and on a small scale resulted in Schimmel & Co.'s distillation test'). It consists in distilling a weighed or measured amount of oil in a fractionating flask over a free flame and weighing the residue. The test is carried out in the following manner: Into a tared fractionating flask of 100 cc. capacity (Vol. I, p. 565, fig. 70), the exit tube of which is not too high, 50 g. of cassia oil are weighed. After the flask has been connected with a tube 1 m. long that serves as condenser, the contents are distilled over a Bunsen burner or alcohol lamp. At first some water passes over with a cracking noise, then the thermometer rises rapidly to 240° and the bulk of the oil distils over between 240 and 260°. The end of the distillation is indicated by the formation of white fumes that result from the decomposition of the residue. The thermometer then rises to 280 and 290°.