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

Potentiometric determination of dissociation constants of xanthic acids

V. Hejl and F. Pechar

Geologisches Institut der Tschechoslowakischen Akademie der Wissenschaften, Prag

Abstract: The dissocn. consts. and pH of xanthic acids were studied in relation to their structural formulas. These exptl. values, Kd × 104, of ethyl, propyl butyl, n-amyl, n-hexyl, n-heptyl, and n-octylxanthic acids (I) were calcd. from a modified Cook-Nixon equation (CA 44: 6229a): 34.0 ± 2, 8.52 ± 0.01, 5.3 ± 0.2, 3.6 ± 0.3, 2.6 ± 0.2, 2.4 ± 0.3, and 1.7 ± 0.3, resp. As the mol. wts. of the I are increased, the dissocn. consts. decrease. The increase of CH2 groups in the mol. of I affects directly the decrease of the dissocn. const., which graphically can be expressed by a hyperbola. The equation is: log(Kdt × 104) = a0 + a1x-1, where Kdt is the theoretical dissocn. const., x the no. CH2 groups plus 1, and a0 and a1 are coeffs. The definitive equation for the calcn. of the dissocn. const. is: log(Kdt × 104) = -0.134681 + 3.321683x-1. For the detn. of the dissocn. consts., dil. aq. solns. were applied because of their higher stability.

Full paper in Portable Document Format: 214a261.pdf (in Czech)

Chemical Papers 21 (4) 261–266 (1967)