To extract apomorphine, the bases are precipitated by sodic bicarbonate, and the precipitate extracted by ether or chloroform, either of which solvents leaves morphine undissolved. The apomorphine is again converted into hydrochloride, and once more precipitated by sodic bicarbonate, and is lastly obtained as a snow-white substance, rapidly becoming green on exposure to the air. The mass dissolves with a beautiful green colour in water, and also in alcohol, whilst it colours ether purple-red, and chloroform violet.
A test for apomorphine is the following:—The chloride is dissolved in a little acetic acid and shaken with a crystal of potassic iodate (KIO3); this immediately turns red from liberated iodine on shaking it up with a little chloroform; on standing, the chloroform sinks to the bottom, and is coloured by the alkaloid a beautiful blue colour; on now carefully pouring a little CS2 on the surface of the liquid at the point of junction it is coloured amethyst owing to dissolved iodine, and apocodeine gives a similar reaction.
Apomorphine is the purest and most active emetic known: whether injected beneath the skin or taken by the mouth, the effect is the same—there is considerable depression, faintness, and then vomiting. The dose for an adult is about 6 mgrms. (·092 grain) subcutaneously administered.
§ 381. The reactions of some of the rarer alkaloids of opium with sulphuric acid and ferric chloride are as follows: none of them have at present any toxicological importance:—
TABLE SHOWING SOME OF THE REACTIONS OF THE RARER ALKALOIDS OF OPIUM.
| Alkaloid. | Formula. | Reaction with Warm Sulphuric Acid. | Reaction with Ferric Chloride. | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Codamine, | C20H25NO4 | - | Dirty red-violet colour, turning dark violet on the addition of HNO3. | - | Dark green. | ||||
| Landamine, | C20H25NO4 | ||||||||
| Landanosine, | C20H27NO4 | - | Dirty green to brownish-green. | - | No colour. | ||||
| Protapine, | C20H19NO5 | ||||||||
| Lanthopine, | C23H25NO4 | Dark brown or black. | No colour. | ||||||
| Hydrocotarnine, | C12H15NO3 | Dirty red-violet; not changed by trace of HNO3. | No colour. | ||||||
§ 382. Tritopine (C42H54N2O7).—This is a rare alkaloid that has been found in small quantities in opium. It is crystalline, separating in transparent prisms. Melting-point 182°. It is soluble in alcohol and chloroform, and slightly soluble in ether.[417]
[417] E. Kander, Arch. Pharm., 228, pp. 419-431.