Estimation of properties of dialkylorganophosphorus acidic extractants in two-phase liquid systems

The distribution, dimerization and dissociation constants of dialkylorganophosphorus acidic extractants XYP(O)OH affecting their behaviour in the two-phase liquid systems involving 'dry' solvents have been correlated with the properties of solutes and solvents in accordance with the Kamlet and Taft and Leggett models. It has been demonstrated that dialkyl derivatives of phosphoric, phosphonic and phosphinic acids could be regarded as members of the same family of acidic extractants. As a result, the distribution, dimerization and dissociation constants as well as the products of these constants can be estimated from the appropriate statistically valid correlations involving the molar intrinsic volumes and Kabatchnik constants of considered acids and solvatochromic parameters pi*, alpha and beta of 'dry' solvents. Both compared models are adequate for the analysis and estimation of equilibrium constants of dialkylorganosphosphorus acids; however, the Leggett model has been found as more convenient than the Kamlet and Taft model. (C) 2000 Elsevier Science B.V. All rights reserved.