Synthesis of SO3H functionalized ionic liquids and their applacation

In 2002, SO3H functionalized ionic liquids have been firstly reported by Forbes.[1] This series of functional ionic liquids offered a new possibility for developing environmentally friendly acidic catalysts because it combined the advantages of liquid acids and solid acids: they have uniform acid sites, they are water and air stable, they can be asily separated from the reaction and reused.[2] Furthermore, they have been screened as solvent/catalysts for several classical acid-promoted organic reactions, e.g. alcohol dehydrodimerization and Fischer esterification. [3] However, SO3H-functionalized ionic liquids are still new to the scientific and industrial community and the interests have been increasing dramatically in recent years. We have reported alkylation of phenols by using SO3H- functionalized ionic liquids as catalysts. [4] In a typical experiment, for the synthesis of SO3H functionalized ionic liquids (e.g. [mimC3SO3H][X]). 1,3-propane sultone was mixed with methanol, then 1-methylimidazole was added dropwise under ice bath for 1h, and the reaction (run 40℃ for 1h). After solidification, the product (zwitterions) was washed with methanol and dried under vacuum (120℃, 133Pa) for 8h. A stoichiometric amount of acid(HX) was added to the precursor zwitterions. The mixture was stirred for 8 h at 80℃ to form the ionic liquid. The product phase was separated, and then washed repeatedly with ethyl acetate to remove the impurities, and dried in vacuum at 120℃, 133Pa for 8 h. Fig. 1 Synthesis of SO3H functionalized ionic liquids A series of SO3H functionalized ionic liquids will be tested in esterification, alkylation, etc. Their application potentials will be explored to reach on optimum performance between high yield from homogeneous catalyst and easy separation behavior from heterogeneous catalyst