Synthesis of Ethylene Glycol Via Two-Step Method Catalyzed by Ionic Liquid

Ethylene glycol (EG) is an important chemical in organic chemistry, which can serve as antifreeze agents, brake fluids, and the starting stock for the manufacture of polyurethanes and poly(ethylene glycol)s. Its current manufacture method is direct hydration of ethylene oxide (EO) without any catalyst (Scheme 1, A), which has the disadvantages of critical reaction conditions, low selectivity (90%), a large excess amount of water (20¨C25 mol of water per mol of EO), and intensive energy consumption. (Scheme 1 Synthesis of ethylene glycol with different methods) Due to the advantages of high EG selectivity (100%), low water demand (1-1.5 mol of water per mol of EC), and the mild reaction conditions, hydrolysis of ethylene carbonate (EC) to produce EG (Scheme 1, B) has much potential to substrate for direct hydration method in industry. In addition, ionic liquids (ILs) can play some roles in developing environmental friendly process since the synthesis of EC can smoothly proceed in the presence of ILs. Herein, a clean process for the synthesis of EG catalyzed by ionic liquid has been investigated. The total process was divided into two steps: synthesis of EC, and hydrolysis of EC. From Figure 1a-b, it can be seen that the catalyst is stable in both activity and selectivity for the synthesis of EC and EG after using 260 h. (Figure 1 Results via reaction time) Key words: Ethylene glycol, Ionic liquid, Ethylene carbonate, Synthesis Acknowledgments This work was supported by the National Science Fund of China for Distinguished Young Scholar (20625618); National 863 Program of China (2006AA06Z317) and National Natural Science Foundation of China (20603040 and 20436050).