Volume 1

Chemical technology and analysis of oils, fats and waxes / by J. Lewkowitsch.

  • Lewkowitsch, J. (Julius), 1857-1913.
Date:
1909
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Chemical technology and analysis of oils, fats and waxes / by J. Lewkowitsch. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    51/574 (page 27)
    Grim and Schacht1 prepared a fi-oleo-a-ydistearin by heating a-adistearin with an equal amount of oleic anhydride for six hours to 170° C. at a pressure of 20 to 25 mm., whilst a current of carbon dioxide was passed through the mass. This oleodistearin melted, shortly after being prepared, at 42° C. After being kept for one year it melted at 41° and at 55° C.; after solidification it melted at 42° C. Elaidodistearin, C3H5(0 . C18H330)(0 . C18H350)2, is obtained by the action of nitrous acid on oleodistearin (Henriques and Kiinne2). It melts at 61° C. Dioleostearin, C3H5(0 . C18H330)2(0. C18H350), has been stated by Partheil and Ferii6 to occur in human fat. The occurrence of a mixed glyceride of japanic and palmitic acids having the formula C3H5(C20H40[CO . 0]2)(0 . C16H310) in Japan wax is considered probable by Geitel and v. d. Want (see Yol. II. Chap. XIV. “Japan Wax”). Mixed glycerides containing the acid radicles of other organic acids, as also mixed glycerides containing acid radicles of inorganic acids, will be described under “ Glycerol,” as, with the exception of lecithin, they have hitherto not been met with in nature. Lecithin, however, must be looked upon as a mixed triglyceride, containing two fatty acid radicles and one acid radicle of phosphoric acid. On saponification it furnishes choline,4 glycerol, phosphoric acid, and fatty acids. Hence the following formula is generally ascribed to it: C3H5(OR)(OK). [O. P0(0H)(0 . CH2CH2N(CH3)3OH]. In the case of egg-yolk lecithin5 the fatty acids obtained on saponification contained 24 per cent of linolic, 28*5 per cent of palmitic, and 14*2 per cent of stearic acid (Cousin6). The above-given formula contains an asymmetric carbon atom, and, in agreement herewith, natural lecithin is optically active. A (commercial) preparation of egg-lecithin had [a]D = + 9*84 (P. Mayer1). Like tartaric acid, mandelic acid,8 etc., it is converted, on heating, into the racemic form, which was resolved (by means of steapsin) into its optically active stereoisomerides, inasmuch as lsevorotatory lecithin was isolated (P. Mayer1). This proves that the phosphoric acid radicle, which carries the choline group, is in the y-position. (The glycerol phosphoric acid, obtained at the same time, was also found to be optically active; Willstdtter and Liidecke 9). Lecithin occurs in egg-yolk and in many plant seeds, especially in those derived from the Leguminosce.10 For the commercial pre- 1 Berichte, 1907, 1782. 2 Ibid. 1899, 387. 3 Arch. d. Pliar. 1903, 545. 4 For the preparation of choline from lecithin cp. J. D. Riedel, German patent 193,449. 5 First prepared by A. Strecker (Liebig's Anndlen, 148, 80) ; cp. also Zuelzer, Hoppe-Seyler s Zeit. f. phys. Chemie, 27, 462. 6 Journ. Pharm. Chim. 1903, 102. 7 Biochemische Zeits. 1905, 39. 8 Lewkowitsch, Berichte, 1883, 2721. 9 Berichte, 1904, 3753. 10 Cp. Konig and Schluckebier, Zeit. f. Unters. Nahrg. u. Genussm. 1908, xv. 650. For the quantitative determination cp. G. Fendler, Apotlieker Zeit. 1905, No. 3 ; Riedel, ibid. 1905, 72.