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Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties
Author(s) -
Bwambok David K.,
Marwani Hadi M.,
Fernand Vivian E.,
Fakayode Sayo O.,
Lowry Mark,
Negulescu Ioan,
Strongin Robert M.,
Warner Isiah M.
Publication year - 2008
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20517
Subject(s) - chemistry , ionic liquid , tetrafluoroborate , enantiomer , chirality (physics) , counterion , circular dichroism , nuclear magnetic resonance spectroscopy , chloride , inorganic chemistry , organic chemistry , stereochemistry , ion , catalysis , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L ‐ and D ‐alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L ‐ and D ‐alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L ‐ and D ‐alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263°C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state 19 F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L ‐ and D ‐alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion. Chirality, 2008. © 2007 Wiley‐Liss, Inc.