Imidazolium dialkylphosphates - a class of versatile, halogen-free and hydrolytically stable ionic liquids

In this article a systematic and detailed study on the synthesis and the properties of dialkylphosphate ionic liquids is presented. This class of halogen-free ionic liquids is easily available in high quality and great variability by direct alkylation of nucleophiles, such as 1-methylimidazole, 1-ethylimidazole, 1-butylimidazole and 1-(2-methoxyethyl)-imidazole with different trialkylphosphates, such as trimethylphosphate, triethylphosphate or tributylphosphate. In general, these dialkylphosphate ionic liquids were found to display very attractive physicochemical properties with great technical potential, especially in low temperature (< 200 degrees C) applications with water present. For this specific application area, the materials described here clearly show superior properties compared with alkylsulfate ionic liquids due to their obviously much higher hydrolytic stability.