The constitution of pilocarpine / by Hooper Albert Dickinson Jowett.

  • Jowett, H. A. D. (Hooper Albert Dickinson)
Date:
[1900-1905]
Catalogue details

Licence: In copyright

Credit: The constitution of pilocarpine / by Hooper Albert Dickinson Jowett. Source: Wellcome Collection.

    12/86 (page 581)
    pilocarpine, CnH1402N2Br25 is obtained as the first and principal pro¬ duct of the interaction of bromine and ^sopilocarpine at the ordinary- temperature. When the reaction is carried out in acetic acid solu¬ tion, small quantities of an acid, probably isopilocarpinic acid, C11H]604N2, are formed, together with a very small quantity of mono- bromoisopilocarpine, CnH1502N2Br. Dibronmsopilocarpine is a very feeble base, does not react with methyl iodide, and on reduction yields isopilocarpine quantitatively, identical in all respects with the parent base. On oxidation with permanganate, it yields methylamine, a little ammonia, pilopic acid, and a new crystalline acid, pilopinic acid, C8Hn04N. On further oxidation, the latter acid yields ammonia and pilopic acid. When bromine acts on wopilocarpine in aqueous solution at 100° in a sealed tube, two chief products are formed, dibromoisopilccarpinic acid, C11H1404N2Br2, and monobromoisopilocarpinic acid, CnH1504N2Br, the former being a well-defined, crystalline acid, whilst the latter has only been obtained as an impure oil. Both these acids, on reduction with zinc and glacial acetic acid, yield the same product, isopilocar- pinolactone, CnH1404N2. This substance, obtained in well-defined crystals, is a neutral lactone, and with barium hydroxide yields the barium salt of hydroxy^opilocarpinic acid. It possesses one re¬ markable character, namely, it is non-basic ; it can be recrystallised from hot dilute acids, and does not unite with methyl iodide even at 100°. When dibromowopilocarpinic acid is reduced in alcoholic solution with sodium amalgam, the molecule is broken down and pilopic acid is formed. Dibromopilocarpine has been further studied, and it has been found, contrary to the statements of Pinner and Kohlhammer (Ber., 1900, 33, 1424), who first prepared this substance, that, like its isomeride, dibromowopilocarpine, it is very feebly basic and does not unite with methyl iodide. On reduction, it yields pilocarpine quantitatively, identical in all respects with the parent base. Experiments made to prepare bromocarpinic acid, first de¬ scribed by the above-mentioned authors, proved unsuccessful, and the amorphous acids, obtained by the action of bromine on pilocar¬ pine at 100° in aqueous solution and in a sealed tube, yielded, on reduction, an amorphous acid which was certainly not carpinic acid, but probably pilocarpinic acid, C11H1604N2. In addition to the description, mode of preparation, &c., of the above-mentioned new substances, a number of experiments are re¬ corded, in many cases with negative results, but which have an important bearing on the constitution of the alkaloid. It is shown that ^sopilocarpine is unaffected by reducing agents such as sodium in boiling amyl alcoholic solution or concentrated hydriodic acid at 127°, and does not exhibit the characteristic