Insights into Ionic Liquid/Aromatic Systems from NMR Spectroscopy: How Water Affects Solubility and Intermolecular Interactions

摘要

Abstract Hydrocarbon solubility and chemical interactions in ten imidazolium‐ and pyridinium‐based ionic liquids (ILs) with four different anions (thiocyanate [SCN] ? , dicyanamide [DCA] ? , tricyanomethanide [TCM] ? , and bis(trifuoromethylsulfonyl)imide [NTf 2 ] ? ) have been studied by 1 H and 13 C NMR spectroscopy. The anion structure has the main influence on the anion–aromatic chemical interaction strength; it is directly correlated to the NMR chemical shift deviations but not to the hydrocarbon solubility. The [TCM] ? anion shows the largest chemical shift deviations, but the [NTf 2 ] ? anion has the highest hydrocarbon solubility due to steric effects. Higher water contents decrease the hydrocarbon solubility in ILs. Ion‐water solvation mainly occurs until 1 mol water /mol IL with the saturation limit at 10 mol water /mol IL . Toluene‐ion interactions are stronger than water–ion interactions in [DCA] ? and [TCM] ? ‐based ILs, but they have a similar or even lower strength in [SCN] ? ‐based ILs.