All these bodies can be prepared from choline; their relationship to choline can be readily gathered from the following structural formulæ:—
| Choline. | Neurine. | Betaine. | Muscarine. |
Choline is a syrup with an alkaline reaction. On boiling with water, it decomposes into glycol and trimethylamine. It gives, when oxidised, muscarine. It forms salts. The hydrochloride is soluble in water and absolute alcohol; neurine hydrochloride and betaine hydrochloride are but little soluble in absolute alcohol, therefore this property can be utilised for their separation from choline. The platinochloride is insoluble in absolute alcohol; it melts at 225° with effervescence, and contains 31·6 per cent. of platinum. The mercurochloride is soluble with difficulty even in hot water. The aurochloride (Au = 44·5 per cent.) is crystalline, and with difficulty soluble in cold water; but is soluble in hot water and in alcohol; melting-point 264° with decomposition.
Choline is only poisonous in large doses.
§ 675. Neurine (Trimethyl-vinyl-ammonium hydrate), C2H3N(CH3)3OH.—Neurine is one of the products of decomposition of choline. It is poisonous, and has been separated by Brieger and others from decomposing animal matters. In Brieger’s process, neurine, if present, will be for the most part in the mercuric chloride precipitate, and some portion will also be in the filtrate. The mercury precipitate is decomposed by SH2, the mercury sulphide filtered off, and the filtrate, concentrated, treated with absolute alcohol and then precipitated by platinum chloride. It is usually accompanied by choline; the platinochloride of choline is readily soluble in water, neurine platinochloride is soluble with difficulty; this property is taken advantage of, and the platinochloride crystallised from water until pure. Neurine has a strong alkaline reaction.
Neurine chloride, C5H12N.Cl, crystallises in fine needles. The platinochloride, (C5H12NCl)2PtCl4 (Pt = 33·6 per cent.), crystallises in octahedra. The salt is soluble with difficulty in hot water.
The aurochloride, C5H12NClAuCl3 (Au = 46·37 per cent.), forms flat prisms, which, according to Brieger, are soluble with difficulty in hot water.
Neurine is intensely poisonous, the symptoms being similar to those produced by muscarine.
Atropine is an antidote to neurine, relieving in suitable doses the effects, and even rendering animals temporarily immune against the toxic action of neurine.
When a fatal dose of neurine is injected into a frog there is in a short time paralysis of the extremities. The respiration stops first, and afterwards the heart, the latter in diastole.