Correlating the physical–chemical properties of phthalate esters using the ‘three solubilityʹ approach

A quantitative structure-property relationship (QSPR) method for the correlation of physical–chemical properties and partition coefficients, namely the ‘three solubilityʹ approach, is described and applied to a group of 22 phthalate esters. The solubilities or ‘apparent–solubilitiesʹ of these substances in the liquid state are compiled and correlated against Le Bas molar volume in the three primary media of air, water and octanol. From these solubilities the air–water (KAW), octanol–water (KOW) and octanol–air (KOA) partition coefficients are deduced. Estimated solubilities in water and octanol–water partition coefficients are shown to compare favourably with more recent accurate measurements. A set of selected values is presented, with error limits, which is recommended for use in modelling and assessment studies. Some environmental implications are discussed of the large range in property values for this series.