[415] The Old Vegetable Neurotics.
[416] Munk, Versuche über die Wirkung des Cryptopins, Berlin, 1873. Sippell, Beiträge zur Kentniss des Cryptopins, Marburg, 1874.
§ 377. Rhœadine (C21H21NO6).—Rhœadine was separated from Papaver rhœas by Hesse, and has also been found in Papaver somniferum and in opium. Rhœadine is in the form of small anhydrous tasteless prisms, melting at 230° and partly subliming. In a vacuum sublimation is almost complete, and at a much lower temperature. It is a very insoluble substance, and is scarcely dissolved, when crystalline, by water, alcohol, ether, chloroform, benzene, and solutions of the fixed or volatile alkalies. When in an amorphous state it is rather soluble in ether, and may be dissolved out of any substance by treating with dilute acetic acid, and neutralising by ammonia, and shaking up with ether before the precipitate becomes crystalline. Rhœadine is easily recognised by its striking a red colour with hydrochloric acid. Either spontaneously or on gentle warming, the colour is produced—one part of rhœadine will colour in this way 10,000 parts of acid water blue or purple-red, 200,000 rose-red, and 800,000 pale red. The reaction depends on a splitting up of the rhœadine into a colourless substance, rhœadin, and a red colouring-matter. Rhœadine is not poisonous.
§ 378. Pseudomorphine (C17H19NO4).—Pseudomorphine was discovered by Pelletier and Thiboumery in 1835. As precipitated by ammonia out of the hot solution, pseudomorphine falls as a white crystalline precipitate; but if the solution is cold, the precipitate is gelatinous. It possesses no taste, and has no action on vegetable colours. On heating, it decomposes and then melts. It dissolves easily in caustic alkalies and in milk of lime, but is insoluble in all the ordinary alcoholic and ethereal solvents, as well as in diluted sulphuric acid. The most soluble salt is the hydrochlorate (C17H19NO4HCl + H2O), and that requires 70 parts of water at 20° for solution. Various salts, such as the sulphate, oxalate, &c., may be prepared from the hydrochlorate by double decomposition. Concentrated sulphuric acid dissolves pseudomorphine gradually, with the production of an olive-green colour.
§ 379. Opianine (C66H72N4O21).—Opianine crystallises in colourless, glittering ortho-rhombic needles. Ammonia precipitates it from its solution in hydrochloric acid as a fine white powder. It is without odour, and has a bitter taste. It is a strong base, and is soluble in cold, but slightly soluble in boiling water. It is also but little soluble in boiling alcohol.
An alcoholic solution of the alkaloid gives a voluminous precipitate with mercuric chloride; after standing a little time, the precipitate becomes crystalline, the crystals being in the shape of fine needles. They have the following composition—C66H72N4O21, 2HCl, 2HgCl—and are with difficulty soluble in water or alcohol.
Opianine, administered to cats in doses of ·145 grm., produces complex symptoms—e.g., dilated pupils, foaming at the mouth, uncertain gait, paralysis of the hinder extremities, and stupor—but the alkaloid is rare, and few experiments have been made with it.
§ 380. Apomorphine (C17H19NO3).—Apomorphine is a derivative of morphine, and is readily prepared by saponifying morphine by heating it with dilute hydrochloric acid in sealed tubes. The result is apomorphine hydrochloride, the morphine losing one molecule of water, according to the equation C17H19NO3 = C17H17NO2 + H2O.