Pilocarpine and the alkaloids of jaborandi leaves / by Hooper Albert Dickinson Jowett.

  • Jowett, H. A. D. (Hooper Albert Dickinson)
Date:
[1900?]
Catalogue details

Licence: In copyright

Credit: Pilocarpine and the alkaloids of jaborandi leaves / by Hooper Albert Dickinson Jowett. Source: Wellcome Collection.

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    under those circumstances to extract an appreciable quantity of the bases. Pilocarpine nitrate was dissolved in water, excess of soda added, and the liquid extracted four times with chloroform, 52 8 per cent, of the base being thus removed. The alkaline liquid was now rendered acid, excess of ammonia added, and the rest of the alkaloid extracted by shaking once with chloroform. Petit and Polonowsky’s statement therefore requires modification. When the base is set free with caustic soda, it is extracted slowly and incompletely by chloroform; ammonia should, therefore, always be used. Specific Rotation of Pilocarpine. Petit and Polonowsky found the specific rotation of the base to be + 106°, Poehl having previously obtained the value [a]D +101 0 . But although aware of the fact that the base retains the last traces of solvent with great avidity, they do not indicate how this difficulty was overcome. In the following experiments, after the rotation had been taken, a known quantity of the liquid (for example, 4 or 5 c.c.) was placed in a tared dish, exactly neutralised with very dilute aqueous nitric acid, and evaporated to dryness in a vacuum desiccator. In this way, from the amount of nitrate found, the concentration of the solution used can be calculated. The following results were obtained : aD = +10° Z = 0-5 dcm.; c = 19’83 ; [a]o= +100'8 aD = +14-3°; l = l dcm. ; c —14*188 ; [a]D= +100-8° aD= + 2-1° ; l = 2’l dcm. ; c = 1-0641 ; [a]D= +100° Mean of three determinations, [a]D= + 100-5.° Petit and Polonowsky have shown that caustic alkali affects the rotation of pilocarpine in a peculiar manner, and explain this by sup¬ posing that the base is the anhydride of an acid with a lower rotation : on treatment with caustic soda, the salt is formed which gives the rota¬ tion of the acid. They boiled pilocarpine with excess of caustic soda, then titrated back with decinormal acid, so that there was exactly a molecule of caustic soda present to each molecule of pilocarpine, and, on examining the resulting solution, found that the specific rotation had fallen to +23-8°. In the same paper, however, they point out that pilocarpine is converted into isopilocarpine by boiling with caustic soda, and as the latter has a lower rotation than the former, their experiment is invalid. To ascertain the effect of alkali, mixtures of pilocarpine and caustic soda in varying proportions were made, one being kept for a month, whilst another was treated with hot caustic soda. The following results were obtained :