The constitution of pilocarpine. Pt. V. Conversion of isopilocarpine into pilocarpine / by H.A.D. Jowett.
- Jowett, Hooper Albert Dickinson, 1870-1936.
- Date:
- [1905]
Licence: Attribution 4.0 International (CC BY 4.0)
Credit: The constitution of pilocarpine. Pt. V. Conversion of isopilocarpine into pilocarpine / by H.A.D. Jowett. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![A quantity of pure isopilocarpine nitrate (m. p. 159°; [a]D + 35-7°) was recrystallised from alcohol, and the mother liquors evaporated to a small bulk. The crystals which separated from the mother liquor melted at 159°, thus proving the homogeneity of the salt. Fifty grams of the nitrate first mentioned were converted into the base, dissolved in alcohol, 30 grams of potassium hydroxide in alcoholic solution added, and the whole heated on a water-bath in a reflux apparatus for 3 hours. The base was regenerated and converted into the nitrate, which was then fractionally crystallised. The first fraction (40 grams) melted at 159°, and had [a]D + 36-2°. It was therefore pure isopilocarpine nitrate. From the mother liquors, two crops of crystals were obtained, both of which melted at 144° and had [a]D + 58'7°. As the melting point of these two crops of crystals was not altered by recrystallisation, they were converted into the hydrochloride and then crystallised from absolute alcohol. After three recrystallisations, a product was obtained melting at 201°, and a determination of its specific rotation in water gave aD + 1°44'; i = 2dcm. ; c = 09336; [a]D + 92‘8°. Pilocarpine hydrochloride melts at 204° and has [a]D + 91-7°. In order to finally prove the identity of this substance with pilocarpine, the hydrochloride was converted into the nitrate. The nitrate melted at 177—178°, and the melting point was unchanged when mixed with an equal quantity of pilocarpine nitrate. The first fraction obtained in the experiment was recrystallised, and then treated in the same manner with alcoholic potash, and a small quantity of pilocarpine nitrate (m. p. 176°) isolated from the resulting product. It was therefore absolutely proved that pure isopilocarpine nitrate, like pilocarpine nitrate, is converted by the action of alcoholic potash into an equilibrium mixture consisting chiefly of isopilocarpine with a small percentage of pilocarpine. This experiment therefore affords further evidence that pilocarpine and isopilocarpine are not structural isomerides but stereoisomerides. The Wellcome Chemical Research Laboratories, London, E.C. ft, CLAY AND SONS, LTD., BREAD ST. HILL, E. C., AND Bl'XGAY, SUFFOLK,](https://iiif.wellcomecollection.org/image/b22401799_0009.jp2/full/800%2C/0/default.jpg)
