TROPINE (Tropanol), one of the simpler chemical products into which the poisonous alkaloid atropine (q.v.) is converted by the action of acids or alkalis. Tropine is also poisonous but no longer retains the property of dilating the pupil of the eye. It crystallises in colourless plates melting at 63° C and boiling at 229° C. It is very hygroscopic and readily soluble in water. It is a strongly basic substance forming crystalline salts with acids. When warmed with sodium in amyl alcoholic solution, tropine is transformed into a stereoisomeride, melting at 108° C, and boiling at 240° C, identical with the pseudo-tropine (4/-tropine) obtained from the alkaloid tropa-cocaine with hydrochloric acid.
The chemical constitution of tropine, is revealed by the following reactions. With chromic acid it is oxidised succes sively to tropinone and tropinic acid.
Tropinone (Tropanone) has been synthesised from succindial dehyde, calcium acetonedicarboxylate and methylamine (R. Rob
inson, 1917), whereas tropinic acid by exhaustive methylation fur nishes an unsaturated dicarboxylic acid reducible to n-pimelic acid, CO211. 5. On dehydration with fuming hydrochloric acid tropine yields the oily base tropidine (tropene), an unsaturated compound combin ing with hydrogen halides and reducible to hydrotropidine which is also an oil. The relationships of tropine to its oxidation and de hydration products are shown in the following graphic formulae :— Other organic acids can take the place of tropic acid in this condensation with tropine, and the products, the acyltropines, are termed tropeines. Certain of these possess the mydriatic action exhibited by atropine. (G. T. M.)