Synthesis, Stability and Electrochemical Characterization of New Ionic Liquids Based on Asymmetrical Borates

众所周知，缺乏对称性会导致几乎相同物质的熔点下降。例如，在一个示例中，碳酸亚乙酯显示出约+36 ° C的熔点，而碳酸亚丙酯的液体范围延伸至约-49 ° C，尽管其摩尔质量较高，并且可以容易地过冷至约-80 ° C。因此，当与基于对称硼酸盐的已知离子液体（例如EMIBF 4）相比时，基于不对称硼酸盐的离子液体（IL）可以获得更大的液体范围。一些具有锂抗衡离子的不对称硼酸盐是已知的。但它们缺乏化学稳定性。交换反应需要对称和不对称硼酸盐的混合物。我们假设这种交换反应主要是由非常小的锂离子辅助的，并尝试合成一些不对称硼酸盐和惰性阳离子如咪唑离子的盐。我们的初步工作表明，我们的假设是正确的。合成了一类新的离子液体的第一个热稳定成员，四乙基铵二氟单[1，2-双（2-）-O，O <$]硼酸盐（1-）。因此，我们提出了一个项目，包括合成和电化学表征的新离子液体的基础上不对称硼酸盐与一个和二齿配体和阳离子的咪唑，锍和铵类型。此外，计划在中等温度下进行长期稳定性研究，其中通过NMR测量长期研究上述硼酸盐溶液的组成。

It is well known that lack of symmetry entails a drop in the fusion point of nearly equal substances. E.g., ethylene carbonate shows a fusion point of about +36°C whereas the liquid range of propylene carbonate extends to roughly -49°C despite its higher molar mass and may be easily supercooled to about -80°C. Thus larger liquid ranges may be obtained for ionic liquids (ILs) based on asymmetric borates when compared to known ILs which are based on symmetric borates such, e.g. EMIBF4. Some asymmetric borates with lithium counter ions are already known. However they show a lack of chemical stability. Exchange reactions entail mixtures of the symmetric and asymmetric borates. We have assumed that this exchange reaction is mainly assisted by the very small lithium ion and tried to synthesize some salts with asymmetric borates and inert cations such as imidazolium ions. Our promising preliminary work showed that our assumption is correct. The first thermally stable member of a new class of ILs was synthesised, tetraethylammoniumdifluoromono1, 2-oxalato(2-)-O,O¿]borate (1-). Therefore we propose a project including synthesis and electrochemical characterisation of new ILs based on asymmetric borates with one- and bidentate ligands and cations of imidazolium, sulfonium and ammonium types. In addition, a long time stability investigation is planned at moderate temperatures, where the composition of the solution of above mentioned borates is studied by NMR-measurements over a long period.