NMR spectroscopy in studies of new chiral ionic liquids

摘要

Chiral ionic liquids (CILs) were discussed as new potential media for enantioselec-tive organic synthesis, including enantioselective polymer synthesis. NMR spectra of new CILs, whose structures are shown in formulas (I) -(IV), were investigated in detail. In the case of H NMR analysis of those compounds two characteristic doublets were observed - diaslerotopic protons (AB spin system). In order to precisely determine the spectral position of each proton and carbon, but also to attribute in a detailed way the type of their signals, two-dimensional spectra were obtained. Additionally, ~1H NMR and ~(13)C NMR spectra indicated notable differences in the chemical shifts depending on the anion used. Comparing the differences between values of the chemical shifts, the anions, but also the quaternary ammonium salts, depending on the amine used, were ordered according to their increasing shielding capacities.