Kinetic study of the dissociation of Ba2+-C222 cryptate in binary dimethylsulfoxide-acetonitrile mixtures

The dissociation rates of the Ba2+-C222 cryptate in different dimethylsulfo xide-acetonitrile mixtures have been studied spectrophotometrically using m urexide as a suitable metallochromic indicator. The activation parameters E -a, Delta H double dagger and Delta S double dagger for the dissociation of the cryptate were determined from the temperature dependence of the dissoc iation rate constants (k(d)). The correlation of the dissociation rate cons tant with the stability constant (K-s) of the barium cryptate was investiga ted. There is a linear relationship between log K-s and the activation para meters E-a, Delta H double dagger and Delta S double dagger and the mole fr action of acetonitrile in the mixed solvent.