Transfer free energies of some ions from water to dimethylsulfoxide-water and urea-water mixtures

The standard free energies of transfer (G _t ^o ) of some electrolytes from water to aqueous mixtures of dimethylsulfoxide (DMSO) and of urea have been split into the contribution from individual ions by use of the reference electrolyte Ph ₄ AsBPh ₄ (RE), where Ph=phenyl. For each of the solvents, G _t ^o (Ph ₄ AsBPh ₄ ) was determined from the solubility products of the salts KBPh ₄ , Ph ₄ AsPi, and KPi, where Pi=picrate ion. The observed G _t ^o (i) values for the individual ions are strikingly different from the corresponding values obtained by the simultaneous extrapolation (SE) procedure reported earlier.