Licence: Public Domain Mark
Credit: The stereochemistry of hyoscine / by Harold King. Source: Wellcome Collection.
![for the present remain undecided. In this connexion, however, it is possibly significant that Wentzel [Dissertation, cited by Hesse, J. pr. Chem., 1901, [ii], 64, 274), by crystallising Z-hyoscine hydro- bromide from alcohol, obtained a lsevo-hyoscine hydrobromide of much higher rotatory power, namely, [a]D —32*9°, which fell, on keeping, to — 25'8°, the usually observed value. Hesse [ibid., 353) claims to have partly substantiated this observation. This enhanced value for the anhydrous Z-hyoscine hydrobromide gives a calculated value [a]D -f 24‘8° for the ^-a-bromo-7r-camphor- sulphonate, a value of the same order as that observed, [a]D -f 25'5°, for the labile bromocamphorsulphonate described above. The present author has obtained another Z-hyoscine bromo¬ camphorsulphonate, [a]D +17’9°, m. p. 200°, during the resolution of a weakly active hyoscine by means of a-bromo-7r-camphor- sulphonic acid. The amount of material was, however, only sufficient to prove the identity of the Z-hyoscine. It is not improb¬ able that the acid contained in this salt is an isomeric acid which was present as an impurity in the original ammonium a-bromo-7r- camphorsulphonate used. Experimental. Preparation of dl-apoHyoscine from \-Hyoscine. The method employed for preparing this base is a modification of that given by Willstatter and Hug [loc. cit.). Z-Hyoscine hydrobromide (3*87 grams) was converted into the base by the use of sodium hydrogen carbonate and chloroform. The chloroform-free base was warmed gently with 10 c.c. of thionyl chloride. The reaction proceeded smoothly, and, after keeping the product overnight, the thionyl chloride was distilled off under diminished pressure, and the last traces were removed by repeated extraction and evaporation with ether. The jS-chlorohydratropy3' oscine hydrochloride was dissolved in a little water, the solution rendered alkaline with sodium hydrogen carbonate, and the base thoroughly extracted with ether. Unlike Z-hyoscine, this chloro- substituted base could be readily extracted. The ethereal solution was evaporated to dryness, leaving a pale yellow oil, which immedi¬ ately became opalescent, and, on digesting on the water-bath with fresh ether, no longer dissolved, but commenced to crystallise at the edges. On keeping for two days, it had crystallised completely in rosettes of stout needles consisting of a_pohyoscine hydrochloride. A 2-5 per cent, aqueous solution was neutral to litmus, and when examined in a 2-dcm. tube proved to have no action on the plane of polarised light.](https://iiif.wellcomecollection.org/image/b30622086_0004.jp2/full/800%2C/0/default.jpg)
