Protoveratrine, C32H51NO11, has been obtained by G. Salzberger[523] from powdered hellebore root, by the following process:—
[523] Arch. Pharm., ccxxviii. 462-483.
The powdered root is first freed from fatty and resinous matters by treatment with ether, and then the fat-free powder is exhausted with alcohol. The alcohol is evaporated off in a vacuum, the extract mixed with much acetic acid water, filtered from the insoluble residue, and treated with metaphosphoric acid; the voluminous precipitate contains much amorphous matter, with insoluble compounds of jervine and rubi-jervine. The precipitate is filtered off, and the filtrate treated with excess of ammonia and shaken up with ether. On separating the ether and distilling, protoveratrine crystallises out, and can be obtained pure by recrystallisation from strong alcohol.
Protoveratrine crystallises in four-sided plates, which melt with charring at 245° to 250°. The base is insoluble in water, benzene, and light petroleum; chloroform and boiling 96 per cent. alcohol dissolve it somewhat; cold ether scarcely touches it, boiling ether dissolves it a little.
Concentrated sulphuric acid dissolves the alkaloid slowly with the production of a greenish colour, which passes to cornflower blue, and, after some hours, becomes violet. Sulphuric acid and sugar gives a different colour to that produced by commercial veratrine. There is first a green colour which darkens into olive green, then becomes dirty green, and finally dark brown. When warmed with strong sulphuric, hydrochloric, or phosphoric acids, there is a strong odour of isobutyric acid developed. Dilute solutions of the salts are precipitated by ammonia, Nessler’s reagent, gold chloride, potassium mercury iodide, cadmium iodide, phosphotungstic acid, and picric acid; no precipitate is produced by tannin, platinum chloride, or mercuric chloride.
§ 471. Veratrine (C37H53NO11) is a crystallisable alkaloid, which is a powerful irritant of the sensory nerves of the mucous membrane, and excites violent sneezing. Treated with concentrated sulphuric acid, it dissolves with a yellow colour, deepening into orange, then into blood-red, and finally passing into carmine-red. If the freshly-prepared sulphuric acid solution is now treated with bromine water, a beautiful purple colour is produced. Concentrated hydrochloric acid dissolves veratrine without the production of colour, but, with careful warming, it becomes beautifully red. This reaction is very delicate, occurring with ·17 mgrm. On saponification veratrine yields veratric acid.
Veratric acid is procatechu-dimethylether acid, and has the constitutional formula,
