Licence: In copyright
Credit: The plant alkaloids / by Thomas Anderson Henry. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![Nicotine is miscible with water in all proportions below G0° and above 210°d On admixture of water with nicotine heat is evolved, and a dihydrate formed.*^ The salts are dextrorotatory, easily soluble in water, and do not crystallise easily ; the hydrochloride, B.HCI, has [ajo + 102-2° ; the sulphate, B2.H2SO4, [ajj, + 84-8°, and acetate, [a]o + 110-29°. When aqueous solutions of nicotine hydrochloride or sulphate are heated in sealed tubes at 180°-250° they become optically inactive.'^ The platinichloride is a yellow microcrystalline sub- stance of indefinite melting-point. The picrate, B. 2C6H2(N02)30H, forms short prisms, m.p. 218°, and is characteristic. Nicotine may be detected by the formation with aqueous solutions of mercuric chloride of a white crystalline precipitate, by the black precijjitate formed under similar conditions with potassium platinic iodide, and the crystalline periodide formed when sohitions of the base in ether are mixed with iodine dissolved in ether. The appearance and melting-point of the picrate are characteristic. These reactions are of importance as distinguishing nicotine from coniine, with which base the tobacco alkaloid is likely to be con- founded. Constitution. The presence of a pyridine nucleus in nicotine was established by Huber,^ Weidel,® and Laiblin,® who, using different oxidising agents, obtained from the base nicotinic acid (/3-pyridinecarboxylic acid). Further evidence of this was afforded by the ready formation of a hexahydronicotine by reduction of the base by sodium and amyl alcohol.’ The empirical formula of nicotine may therefore be extended thus, C5H4N.C5H10N, and most of the recent work has been devoted to the determination of the nature of the CgHjoN residue. The empirical composition of this group is identical with that of piperidine, and the behaviour of ^ Hudson, Zeit. phys. Chem. 1904, 47, 113. ^ Tsakalotos, Ball. Soc. chim. 1909 [iv], 5, 397. 3 Pictet and Rotschy, BericJite, 1900, 33, 2353. « Annalen, 1867, 141, 271. 6 Ibid. 1873, 165, 328. « Berichte, 1877, 10, 2136. ’ Liebricht, ibid. 1886, 19, 2587.](https://iiif.wellcomecollection.org/image/b2196189x_0054.jp2/full/800%2C/0/default.jpg)
