Bwambok David K, Marwani Hadi M, Fernand Vivian E, Fakayode Sayo O, Lowry Mark, Negulescu Ioan, Strongin Robert M, Warner Isiah M
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, USA.
Chirality. 2008 Feb;20(2):151-8. doi: 10.1002/chir.20517.
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 degrees 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.
我们报道了基于氨基酸酯的手性离子液体的合成与表征，这些离子液体由L-和D-丙氨酸叔丁酯氯化物衍生而来。合成过程是通过市售的L-和D-丙氨酸叔丁酯氯化物与多种抗衡离子（如双（三氟甲烷）磺酰亚胺锂、硝酸银、乳酸银和四氟硼酸银）之间的阴离子复分解反应来完成的。圆二色光谱中相反符号的谱带证实获得了两种对映体形式。L-和D-丙氨酸叔丁酯双（三氟甲烷）磺酰亚胺在室温下为液体，有趣的是，它们表现出最高的热稳定性（高达263℃）。此外，这些离子液体表现出对映体识别能力，通过使用液态（19）F核磁共振（NMR）和荧光光谱拆分外消旋莫舍尔钠盐信号得以证明。L-和D-丙氨酸叔丁酯氯化物与硝酸根、乳酸根和四氟硼酸根阴离子形成固体盐。这说明了之前观察到的离子液体合成的可调性，即根据阴离子的变化产生具有不同性质的离子液体。
