New Chiral Ionic Liquids Based on Enantiopure Sulfate and Sulfonate Anions for Chiral Recognition

The synthesis of new chiral ionic liquids with chiral anions is described. Chiral sulfate anions were prepared from alcohols of the "chiral pool" in good yields. Subsequent ion metathesis resulted in new salts with tetrabutylphosphonium and 1-butyl-3-methylimidazolium (BMIM) cations. In addition, the synthesis of chiral sulfonate anions from (R)-phenylethylamine and formaldehyde-sodium hydrogen sulfate, or sodium vinyl sulfonate is shown, giving new Bronsted basic chiral ionic liquids. The potential of the new ionic liquids as chiral shift reagents was explored. It was possible to use, in addition to Mosher's acid and the Bronsted basic ionic liquids, also 2,2,2-trifluoro-1-phenylethanol with the chiral salts. The neutral alcohol was found to interact with the chiral anions by hydrogen bonding.