SelinfDB: A Database of Selectivity at Infinite Dilution for Liquid–Liquid Extraction

One of the most acute health and environmental concerns nowadays is 3Rs (Reduce, Reuse, and Recycle) of organic solvents. The existing technology used for solvent separation is either expensive or inefficient, particularly in the case of azeotrope separation. Ionic liquids (ILs) have already shown potential in liquid-liquid extraction of organic solvents due to their high structural variability. However, which IL will be efficient in a particular separation task is not always known, and experimental screening for selective ILs can be expensive and time-consuming. The preferable alternative is to use selectivity at infinite dilution (S-infinity). In this study, the database for S-infinity was developed by computationally processing activity coefficients at infinite dilution from free available sources. S-infinity was compared to experimental values of selectivity where possible, and the results show that there is an approximate to 80% chance that a "selective" IL, according to S-infinity, will be selective in liquid-liquid extraction. The results were analyzed with respect to the chemical classes of azeotrope components, showing quite a difference in S-infinity to selectivity translation. An example of structure-property analysis was given to illustrate the usefulness of the database for understanding the effects of the structure on S-infinity and design of new ILs for breaking particular two-component systems. The SQL database is freely available online and can be used for the intelligent search for better liquid-liquid extractants.