Abstract: Some new amino acid ionic liquids (ILs) derived from Valine (Val) were studied using both experimental and theoretical methods. First, the Val fluoborate (ValBF4), Val hydrochloride (ValCl), Val nitrate (ValNO3), paratoluenesulfonic acid Val salt (ValTsO), Val sulfate (Val2SO4), and Val phosphate (Val3PO4) were synthesized with one-step microwave synthesis method, and their physicochemical properties, including the IR spectra, melting points, thermostability and optical rotation were studied experimentally. It was found that ValBF4 and ValPO4 have potential in further application for their low melting points (less than 100oC). By using the combination of n-heptane and thiophene as model gasoline, the physical desulfurization effect of ValNO3 was investigated. Quantum chemistry calculations were also performed and the theoretical results were used as the supplementation or explanation for experimental study. Geometry optimizations on the single molecules of the Val complexes in gas phase were performed with DFT B3LYP/6-311++G** method, and the vibration frequencies of each optimized molecule were analyzed at the same level method. The binding energies between ions were calculated and the natural bond analysis was also performed. It was found that the combination of experimental and theoretical methods can help us to explore such kind of system more deeply and can provide some new idea for further design of amino acid ionic liquids.

Key words: Valine, Ionic liquids, Microwave synthesis, Desulfurization, Density functional theory (DFT)