Synthesis Of Chiral Ionic Liquids From Amino Acids

Because of their unique physical and chemical properties, room temperature ionic liquids(RTILs) are now expected to be an alternative to conventional volatility solvents for organic reactions.Recently, design and synthesis of RTILs with controllable physical and chemical properties or even specific functions has been developed for specifically requirements. Combine chiral with ionic liquids is an important way of the function of ionic liquids. People focused on the synthesis of chiral ionic liquids(CILs) for their particularly potential applications to chiral discrimination, including asymmetric synthesis and chiral catalysis. But up to now,most of CILs are derived from chiral cations, only part of them derived from chiral anions.In this paper, a series of chiral ionic liquids([emim][I-Ala],[emim][I-Val]) composed of 1-ethyl-3-methylimidazolium cation([emim]) and chiral anions derived from natural amino acids modified with perfluorobutylsulfonyl groups were synthesized through the acid-base reaction.Three chiral anions: N-perfluoroethyl- sufonyl alanine ethyl ester([I-Ala]) and N-perfluoroethylsufonyl valine ethyl ester([I-Val]) and N-perfluoroethylsufonyl leucine ethyl ester([I-Leu]) were synthesized from amino acids through esterification and sulfonylation. A new method was builded to synthesize these CILs through improving the condition of reactions. The optical activity of CILs were also detected.The results of experiment showed amino acid methyl esters could react easily with perfluorobutylsulfonyl fluoride without any solvents and catalyzer in low temperature. Product could be separated easily from reaction system using a simple method as there were only two reagent in the reaction system. All of the CILs synthesized in this paper could be used in chiral synthesis as they had low melting point and optical activity.