ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The effect of tannin on complex ions in solutions of chromic salts

V. Kubelka

Research Institute of cellulose, Bratislava

Abstract: Tannin (I) in soln. of basic Cr sulfate enters into chromic complexes (II) and displaces SO₄, OH, and H₂O groups. In this reaction H₂SO₄ is set free and the active acidity of the liquor is increased. I replacing SO₄ groups in II is bound firmer than I replacing H₂O (cannot be titrated oxidometrically). In the reaction with hide of liquor contg. basic Cr sulfate and I, II is bound by the acidic groups of collagen and I by the basic groups. In the first case I is bound on collagen through II and in the second case II is bound on collagen through I. In semichrome leathers the tanning effects of Cr and I are not additive because these materials are bound on collagen not only 'side by side' but also 'over each other.'

Full paper in Portable Document Format: 73-4a225.pdf (in Czech)

Chemical Papers 7 (3-4) 225–246 (1953)