Modelling the behaviour of switchable-hydrophilicity solvents

A switchable-hydrophilicity solvent (SHS) is a solvent that in one state forms a biphasic mixture with water but can be reversibly switched to another state that is miscible with water. We describe a mathematical model of the behaviour of CO2-triggered SHS that narrows the search field for these solvents in terms of their basicity and hydrophilicity. By its predictive power, the mathematical model can assist in the optimization of processes using SHSs in terms of extrinsic parameters such as pressure and the relative volumes of solvent and water used. Models are presented for both a two-liquid system (consisting of the amine solvent and water) and a three-liquid system (consisting of the amine solvent, water, and 1-octanol). Partitioning data with toluene as the third component is also shown for comparison with 1-octanol.