Volume 1

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

  • Lewkowitsch, J. (Julius), 1857-1913.
Date:
1904
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.

    24/454 (page 4)
    In nature apparently only the triglycerides occur; the mono- glycerides and diglycerides are, as a rule, not met with in freshly prepared fats. True, Reimer and JFill 1 have found in old rape oil the diglyceride of erueic acid, C3H5(0. C22H410)2(0H), but this exception to the general rule is only an apparent one, as it is most likely that the rape oil in question had become rancid with formation of free erucic acid, whilst dierucin separated as a solid mass (see p. 26). The monoglycerides and diglycerides are obtained synthetically by the following two general methods. JBerthelot’s'2 method consists in heating together fatty acids with glycerol in a sealed tube. Inas- much as it is difficult to so control the reaction that only a mono- glyceride or a diglyceride be formed, it will be found more convenient to employ the following method : — Mix equivalent quantities of a-monochlorhydrin in the case of monoglycerides and a-dichlor- hydrin or /I-dibromhydrin in the case of diglycerides with the finely powdered sodium salts of the fatty acids (Romburgli,3 Guth 4), and heat the mixture. The sodium chloride formed separates at the bottom of the vessel. The glyceride is then extracted with ether, and filtered over charcoal. (See Appendix.) Monoglyeerides According to the position which the fatty acid radicle occupies in the molecule, two isomeric monoglycerides are possible, as explained by the following formulae, in which R denotes the fatty acid radicle :— 0. R 0.H C;,H5 0 . H or C3Hs 0 . R O.H O.H The compounds corresponding to the first formula will be denoted as a-compounds. The following monoglycerides have been prepared hitherto:— Monoformin, C3H5(0. CHO)(OH)2, is obtained by heating mono- chlorhydrin with sodium formate to 160° C. It is also formed when oxalic acid is heated together with glycerol to 190° C. Mono- formin boils in vacuo at 165° C. Monoacetin,5 C:iH.(0. C2H30)(0H)2, is obtained together with diacetin and triacetin on heating anhydrous glycerin with glacial acetic acid. It is a thick liquid, easily soluble in water and alcohol, very sparingly soluble in ether, and almost insoluble in benzene. Monoacetin is very hygroscopic; its specific gravity is 1‘2212 at 15° C. (water of 15° C. = 1). It boils without decomposition at 130°-132° C. under a pressure of 2-3 mm. At higher pressures it is decomposed. 1 Berichtc, 1S86, 3320. 2 Ckiirde organiquc fundee sur la synthise. Paris, 1860, vol. ii. 3 Recueii des Travaux chimiques des Pays Bas, 1882, 186. 4 Xeit.f. Biologic, 14, 78. 5 Geitel, Journ. ]>ralct. Chew. 1897 (55), 422, 425.