Print version ISSN 0100-4042
On-line version ISSN 1678-7064
MOREIRA, Ícaro de Sousa; PARENTE, Letícia Tarquinio de Sousa and FRANCO, Douglas Wagner. The acid-base properties of 4,4'-dithiodipyridine. Quím. Nova [online]. 1998, vol.21, n.5, pp.545-550. ISSN 0100-4042. http://dx.doi.org/10.1590/S0100-40421998000500002.
Despite the importance of the 4,4'-dithiodipyridine as an electrode modifier on the protein electrochemical studies and as a remarkable bridged-ligand on conducting electronic density in binuclear mixed valence complexes, there is no data available in the literature concerning acid-base behavior of this compound. Aiming to afford such information we undertook the ionization equilibrium study of this ligand. Although two acid species, DTDPH+ and DTDPH2+ have been detected in solution, only the diacid-form was possible to be isolated as a perclorate salt DTDPH2(ClO4)2. The ionization constants for the two step equilibrium processes (pKa1=2.70 and pKa2=4.80) were determined by using the spectrophotometric technique and aqueous solutions of CF3COONa, m=0,1 mol.L-1 .
Keywords : 4,4'-dithiodipyridine; equilibrium study; ionization constants.