Highly Efficient Dehydration of Ethyl Acetate using Strong Hydrophilic Ionic Liquids

Ethyl acetate (EA) is a widely used solvent and raw material in chemical and pharmaceutical industries. The removal of the low water content (<2%) in EA is difficult using the conventional separation method. The strong hydrophilicity of ionic liquids (ILs) can provide a new opportunity for highly efficient EA dehydration, and the water can be easily removed through liquid–liquid extraction. In this work, several kinds of hydrophilic ILs with the carboxylate group for EA dehydration were designed and prepared. The liquid–liquid equilibrium of ILs with EA–water was measured. Among the ILs, 1-ethyl-3-methyl-imidazolium acetate ([C2mim]OAc) showed the best extraction performance for EA dehydration. The water removal efficiency was 99% by single-stage extraction. The partition coefficient of water was 711.26, and the selectivity of water to EA was 2.64 × 104. After three stages of extraction, the water content of EA was as low as 84 ppm. Hydrogen bonding played an important role in the dehydration of EA with [C2mim]OAc, as determined from quantum chemical calculations.