The Synthesis Of Chiral Ionic Liquid And Their Application In Aldol Reaction

Ionic liquids(ILs) are organic molten salts with melting points close to or lower than room temperature comprised of cation and anion completely. In recent years, Ionic liquids(ILs) as green solvents have attracted increasing interest in the chemical community owing to their unique properties of favorable solubility, thermochemical stability, low volatility, low toxicity, wide range of liquid states, incombustibility, reusability, wide electrochemical window, adjustable acidity and so on. Nowadays ionic liquids are widely applied in the areas of organic synthesis, polymer chemistry, electrochemistry, analytical chemistry, material chemistry and separation technology. The synthesis and application of new or functionalized chiral ionic liquids have attracted considerable attention in view of the unique properties of ILs which can be designed easily, wide range of applications, low toxicity and low pollution. The synthesis of new chiral ionic liquids, started from natural amino acid, was discussed, and the performances of the prepared ILs as an new catalyst were evaluated by aldol reaction. The main studies are shown as follows:1. The synthesis of six kinds of chiral ionic liquids was achieved with good yields in three steps from natural amino acid, which underwent Boc protection of amino acid and amidation reaction and quaternization reaction. Finally, the new chiral ionic liquids with BF4-or PF6-as anion were obtained by using the anion exchange method, which is simple and environmental friendliness.2. Chiral ionic liquid b was prepared from proline and leucine via Boc protection of amino acid, amidation reaction, the reduction of esters, the halogenation of alcohols and quaternization reaction. The method has the advantages of cheap raw materials, high yields of each step and simple operation, etc. At the same time, we explored the synthesis methods of chiral ionic liquid a from natural amino acid.3. The study of aldol reaction with chiral catalyst b was done. The results of the study show:(1) it did not result in the formation of the desired condensation product. In contrast, the further dehydration product, α,β-unsaturated Ketone was obtained in high yield;(2) the highest yield of the reaction was obtained under free-solvent condition, up to90%;(3)the yield was not influenced by the increase of the mount of catalysts;(4) it was found that electronic effect on the reactions was very limited;(5) the ionic-liquid moiety can act as a phase tag to facilitate recycling and reuse of the catalyst.