The action of the cinchona and certain other alkaloids in bird malaria. Pt. 2 / by G.A.H. Buttle, T.A. Henry and J.W. Trevan.

  • Buttle, G. A. H. (Gladwin Albert Hurst), 1899-1983.
Date:
[1934]
Catalogue details

Licence: Public Domain Mark

Credit: The action of the cinchona and certain other alkaloids in bird malaria. Pt. 2 / by G.A.H. Buttle, T.A. Henry and J.W. Trevan. Source: Wellcome Collection.

    20/22 (page 430)
    an ethyl group, under standard, quantitative conditions, as proof of the absence of dihydro-bases and (b) constancy of optical rotation of the base and its salts, when expressed on a uniform basis and taken under standard conditions. The chief effects of this purification are to remove quinine from “cinchonidine ” and quinidine from “cinchonine,” and to eliminate large quantities of dihydro- bases from what have hitherto been commonly regarded as pure cinchonine and pure quinidine. From the pure primary alkaloids the corresponding dihydro- bases have been made by catalytic hydrogenation. The chief constants of the eight pure alkaloids so prepared are recorded in Tables III and IV. Though numerous determinations of the specific rotations of the cinchona alkaloids are recorded, they are for such varied concentrations and solvents, that it is not practicable to use them for comparative purposes. The authors have however repeated their determinations for the dihydrobromides of all eight alkaloids, under the conditions used by Emde in order to establish a more exact comparison with the results of that author. These comparative results are given in Table II. \ Table II. Specific rotations of dihydrobromides of cinchona alkaloids. [a]/, recorded by c (anhydrous ( \ Present Base Salt used salt) Solvent Emde authors Quinine B.2HBr, 3H20 3-5194 Water -181-04°* - 184-4 Dihydroquinine B. 2HBr, 3HaO 3-902 Water -152-7 -153-2 Cinchonidine B.2HBr, 2HaO 4-2575 Water - 112-5 - 111-4 Dihydrocinchonidine B. 2HBr, 2H20 2-0828 Water - 91-9 - 90-6 Quinidine B.2HBr, 3H20 3-6163 Water + 209-5 to + 210-7 + 219-2 Dihydroquinidine B. 2HBr, 3H20 3-6628| Water + 196 + 197-5 + HBr Cinchonine B.2HBr 4-2355 Water + 163-2 + 166-6 Dihydrocinchonine B.2HBr 5-0233 Water + 142 + 143-1 • 950 * Emde gives [a]^ - 183-6° for c 3-9363. f Average of 7 determinations: c = 3-6491 to 3-6836 and [a]^ °’J7 = 193-2 to 197-6°. It will be seen that the two sets of figures are in good agreement so far as cinchonidine and the four dihydro-bases are concerned, the differences ranging from 0-5 to 1-5, which are not greater than might be expected from two workers, making observations on the same substance. With quinine the difference amounts to 3-36°. Emde purified his quinine, first as the acid sulphate and finally as the dihydrobromide and there can be no doubt as to its purity. It is suggested that his lower specific rotation may be due to incomplete drying. Thus, he describes quinine dihydrobromide as a dihydrate, but the present authors found that the loss on drying at 120° in vacuo in seven samples varied from 10-12 to 10-86 % (average 10-37 %). The loss calculated for a trihydrate is 10-0 % and for a dihydrate 6-9 %. In the case of cinchonine the difference is 3-4°. In this instance the salt is anhydrous and the higher figure now recorded is doubtless due to the complete elimination of dihydro cinchonine. Assuming this, the lower figure recorded by Emde corresponds to a cinchonine containing 14-3 % of dihydrocinchonine, which is close to the figure 15-1 % now found (p. 437) for commercial cinchonine after re crystallisation from alcohol until free from quinidine. The figures for quinidine show the largest difference 8-5 to 9-7°. Emde found quinidine dihydrobromide to be a dihydrate whereas the present authors found