Vegetable Tanning by Arthur W
Sept., 1922 THE JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY 829 75-Jablonski and Einbeck, Ledntech. Rundschau, 13 (1921), 41. 82-Thomas, J. Am. Leather Chem. Assoc., 15 (1920), 221. 76-Schultz. J. Am. Leather Chem. Assoc., 15 (19201, 283. 83-Matos, Ibid., 16 (1920), 553. 77-Hart, Ibid., 16 (l920), 404. 84--Welwart, Chem. Ztg., 44 (1920), 719. 78--Hart, Ibid., 16 (1921), 159. SSHoffman, Bn., 63 (1920), 224. 79-Bunicke. Ibid., 16 (l921), 7. 86-Froboese, Z. Nahr.-Genussm., 41 (1921), 113. SO-Pickering, J. SOC.Leather Trades’ Chem., 89 (1920), 305. 87-Bogue, Chem. Met. Eng., 2s (1920), 6, 61, 105, 154, 197 81-Kern, J. Ind. Eng. Chem., 12 (1920), 785. Vegetable Tanning By Arthur W. Thomas CHEMICALLABORATORIES, COLUMBIA UNIVERSITY, New YORK,N. Y. HE NATURE of tannin has beenunder study by organic Nierenstein is also studying the constitution of the catechu chemists for many years, but the outstanding feature tannins. He has recently found3 that Paullinia tannin T of organic chemical investigation was the synthesis of from Paullinia cupunu seeds is a crystalline normal glucoside gallotannic acid (the tannin of oak galls) by Emil Fischer in consisting of 1 molecule of dextrose and 2 molecules of 1918,l which rendered all previous work practically obsolete. gambier-catechin-carboxylic acid, forming a depside. The study of the hydrolytic products of purified nut- K. Freudenberg, formerly associated with Fischer, is con- galls tannin showed that 1 molecule of glucose was combined tinuing that great master’s work on the tannins. He has with a number of molecules of gallic acid, and that gallo- shown4 that Hamameli tannin, which has been isolated in the tannic acid was-actually a pentadigalloyl glucose, with crystalline condition, yields on hydrolysis with tannase the formula gallic acid and an unidentified aldo-hexose in the proportions required for a digalloylhexose.
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