Synthesis and characterization of task-specific ionic liquids possessing two Bronsted acid sites

Task-specific ionic liquids possessing two Bronsted acid sites with -COOH, HSO4-, or H2PO4 groups have been designed, synthesized, and characterized. Under mild conditions and without any additional organic solvent, the esterification of isopropanol by chloroacetic acid could be carried out in these new task-specific ionic liquids. In comparison with most of acidic ionic liquids in current use, these ionic liquids are halogen free and more environmentally benign as media and catalysts.