Analysis of liquid–liquid distribution constants of organophospohorus based extractants Original Research Article

Linear solvation energy relationships (LSER) analysis of distribution of organophosphorus based solutes between aqueous phase and organic solvents has been performed applying the Kamlet and Taft, as well as Leggett models of solvent effects. A correlation permitting the prediction of unknown and/or correction of uncertain values of Kabachnik induction constants from the structure of alkyl and alkoxyl substituents attached to phosphorus has been proposed. Dialkylorganophosphorus based acids in two-phase liquid systems are reasonably well described by the dependence of their dissociation and distribution constants on the ionic strength of the aqueous phase, the property parameters of solvents and structural properties of alkyl and alkoxyl substituents, respectively. The satisfactory results have also been obtained for the distribution constants of trialkylphosphine oxides influenced by the properties of solutes, solvents and ionic strength of the aqueous phase, respectively. The analysis of solvent effects upon the distribution constants of neutral esters of organophosphorus based acids has been performed for five solutes only, all of the low hydrophobicity, i.e. the first four members of homologous series of trialkyl esters of phosphoric acid and dimethyl methylphosphonate, respectively.