INTERACTION OF DIVALENT METAL-IONS WITH D-GLUCONIC ACID IN THE SOLID-PHASE AND AQUEOUS-SOLUTION

The interaction of D-gluconic acid with Mn-II, Co-II, Ni-II, Cu-II, Cd -II, Hg-II and Pb-II has been investigated. Compounds of the type Mn(D -gluconate)(2) . 3H(2)O, Co(D-gluconate)(2) . 3H(2)O, Ni(D-gluconate)( 2) . 3H(2)O, Cu(D-gluconate)(2) . 3H(2)O, Cd(D-gluconate)(2), Hg(D-glu conate)OH and Pb(D-gluconate), have been isolated. These metal-sugar s alts were characterized by elemental, thermogravimetric analyses and F T-IR, UV-vis absorption, EPR and C-13 NMR spectroscopies. In addition, a quantitative study of the equilibria involved in the interaction of this sugar and the above mentioned metal ions in an aqueous medium wa s carried out by means of potentiometric measurements of the hydrogen ion concentrations at 20 degrees C and mu = 0.100 M (NaNO3). On the ba sis of spectroscopic studies, possible structures of these complex spe cies were discussed.