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.

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    LXXIX.—The Constitution of Pilocarpine. Part 1. By Hooper Albert Dickinson Jowett, D.Sc. In a previous communication (this vol., 494), it was shown that the constitutional formula previously proposed for pilocarpine by Hardy and Calmels must be abandoned, and an account was given of certain preliminary experiments on the constitution of isopilocarpine. Since then, Pinner and Kohlhammer (Ber., 1900, 33, 1424) have confirmed these conclusions, and have described several compounds of pilocar¬ pine with bromine, as well as a new crystalline product, bromocarpinic acid, C10H15O4N<jBr. The present paper contains a full account of the isolation and identification of the products formed by the oxida¬ tion of isopilocarpine with permanganate, and of the reactions of the base with soda lime, fused caustic potash, and methyl iodide. In attacking the problem of the constitution of pilocarpine, two difficulties are encountered, first, the remarkable stability of isopilo¬ carpine towards many reagents, for example, caustic potash or nitric acid, and secondly, the high price of the alkaloid, which renders it necessary to work with small quantities of material. Although it is not yet possible to propose a formula for the alkaloid, yet, from the results recorded in this paper, the existence of certain groups in the molecule can be shown to be highly probable. From the fact that isopilocarpine only with difficulty forms salts with metallic hydroxides, such as sodium, barium, and copper hydroxides, as well as from its behaviour towards hot alkali, it is legitimate to conclude that it contains a lactone group. In many reactions, the nitrogen is eliminated as ammonia and methylamine, and when isopilocarpine methiodide is treated with caustic potash, methylamine alone is formed. Di-alkyl derivatives of isopilocarpine could not be prepared, thus confirming Chastaing’s observation (Gompt. rend., 1885, 101, 507), and since methyl iodide may be supposed to act as an acid towards a base, it must be assumed that of the two nitrogen atoms, the one which confers the basic character on isopilo carpine is evolved as ammonia, whilst the other is split off as methyl¬ amine, and does not act as basic nitrogen. Herzig and Meyer (Monats., 1898, 19, 56) have stated that one methyl group is attached to a nitrogen atom, and since methylisopilocarpine cannot be further methylated, it must be inferred that the nitrogen atoms occur as !NH and IlST’CHg, the former being that to which the basic character of isopilocarpine is due. Further, the facts, that isopilocarpine is stable towards acids or alkalis and at high temperatures, and that when methylisopilocarpine