Recognition of Quebracho Bark.—G. Fraude recommends the following process: 5 grams of the bruised bark are boiled for about 5 minutes with 25 cc. of very light coal-benzin; the slightly colored liquid is filtered while hot and agitated with 10 cc. of dilute sulphuric acid; the aqueous solution is mixed with excess of ammonia, shaken with 10 cc. of ether, the etherial liquid evaporated in a test tube and the residue boiled with solution of perchloric acid. In place of the latter a little water and 3 or 4 drops of concentrated sulphuric acid are added to the residue, and afterwards a very minute quantity of potassium chlorate. In either case, after boiling for some time, a beautiful intense fuchsin-like color is obtained, due to the presence of aspidospermina.—Ber. Deutsch. Chem. Ges., 1881, p. 319.
Alkaloids of Quebracho Bark.—O. Hesse has satisfied himself that Wulfberg's assertion concerning the identity of Fraude's aspidospermina with Hesse's paytina is incorrect. Hesse has also isolated a second alkaloid, quebrachina, which has the composition C21H26N2O3, crystallizes in small, white, anhydrous prisms, melts at about 215°C. (uncorr.), undergoing partial decomposition, dissolves readily in hot, slightly in cold alcohol, and is sparingly soluble in ether. Its solution in pure sulphuric acid has a bluish color, becoming darker in a few hours, and in the presence of lead peroxide is of a magnificent blue. A similar blue color is produced by sulphuric acid in the presence of molybdic acid or of potassium bichromate. Boiled with perchloric acid solution a yellow-colored liquid is obtained. Though these reactions are similar to those of strychnia and curarina, Dr. Petzoldt found it to differ from them in its action upon frogs; however, 0.04 gram was sufficient to kill a small rabbit.
Quebrachina is a strong base. Its sulphate, (C21H26N2O3)2.H2SO4+8H2O, forms colorless short quadrangular prisms, which are freely soluble in alcohol and water. The hydrochlorate is in similar crystals, very sparingly soluble in cold, but readily so in hot water. The salts with other acids are likewise crystallizable and mostly sparingly soluble in water.
Of quebrachina 0.28 per cent. was obtained; of aspidospermina only 0.17 per cent. The new alkaloid, and three other alkaloids observed in quebracho bark, will be further investigated by the author.—Reprint from Ber. der Chem. Ges., 1880, p. 2308.