Abstract
The kinetics of ligand exchange reaction of mercury-aminopolycarboxylates (Hg-Y) with monothiodibenzoylmethane (SBB) is studied by solvent extraction method. EDDA, NTA, EDTA-OH, DPTA-OH, EDTA, methyl-EDTA, GEDTA and DTPA are used as aminopolycarboxylic acid. The reaction rate is determined by the measurements of the radioactivity of 203Hg in the aqueous phase. From the respective dependencies of the rate constant on the concentrations of hydrogen ion, SBB and Y, the formation of the mixed ligand complex was approved in the reaction mechanism. The values of the rate constants and stability constants of Hg-Y are found to be correlated each other with a few exceptions such as the cases of EDTA-OH and DPTA-OH, and the rate determining step is considered to be involved in the step of the dissociation of aminopolycarboxylic acid. The usefulness of the solvent extraction method for the kinetic study of complex formation was proved through the result presented here.
