The relation between natural and synthetial glycerylphosphoric acids / by Frederick B. Power and Frank Tutin.

  • Frederick Belding Power
Date:
[1905]
Catalogue details

Licence: In copyright

Credit: The relation between natural and synthetial glycerylphosphoric acids / by Frederick B. Power and Frank Tutin. Source: Wellcome Collection.

    5/14 page 251
    In our investigation, it is shown that the above conclusion of Willstiitter and Liidecke is invalid, as it is evident that the condi¬ tions under which they prepared their synthetical glycerylphosphoric acid were such as are now known to afford some of the di-ester, CsHf)(OH)<^Q^>PO,OH (compare Carre, loc. cit.). The differences observed by them in the percentages of metal contained in the salts of the natural acid and in those of their synthetical acid do not, therefore, justify their assumption that the latter retained water when heated to the specified temperatures. Furthermore, the observation of Willstiitter and Liidecke that the glycerylphosphoric acid from lecithin possessed optical activity, although certainly proving the presence of the unsymmetrical acid in the preparation, does not necessarily exclude the possibility that some of the symmetrical acid was also present. Inasmuch as the natural acid has in no instance been prepared from a lecithin which was known to be a pure substance (compare Bergell, Ber., 1900, 33, 2584), no proof can as yet be adduced that it is not a mixture of the unsym¬ metrical and the symmetrical isomerides. The same possibility naturally exists with respect to the homogeneity of the synthetical acid, which, howrever, doubtless consists chiefly of the unsymmetrical isomeride. We shall endeavour to prepare both these isomerides in order to compare them, on the one hand with the completely racemised natural acid, and on the other hand with the acid obtained by the interaction of phosphoric acid and glycerol. Experimental. In order to determine and compare the characters of some of the salts of glycerylphosphoric acid, when prepared by definite methods, the following experiments were conducted., I. Twenty-five grams of glycerol and 30 grams of phosphoric acid (sp.gr. L70) were mixed, and heated together for 24 hours (in three periods of 8 hours each), in an oil-bath at 105—110°. The mixture was then added to an excess of milk of lime, the liquid filtered when cold, and the precipitate thoroughly washed with water. The combined filtrate and washings, after being deprived of the excess of lime by means of carbon dioxide, were divided into two portions, (a) and (b), which were evaporated to a small bulk, when some of the salt separated. (a) In one case, the calcium salt which had separated from the hot liquid was collected, and washed with a little hot water. IT 031 of the salt, dried at 125°, gave 0*2940 CaO. Ca= 19*04 percent. (b) In the other case, the calcium salt was completely precipitated
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