Preparation and Applications in Organic Reactions of Polyethylene Glycol Functionalized Ionic Liquids

The ionic liquids have been widely applied in the organic synthesis as a new reaction medium or catalysts, because of their special properties and excellent solubility with organic and inorganic compounds. Recently, polyethylene glycol-functionalized ionic liquids have attracted much attention from the researchers engaging in organic synthesis. The polyethylene glycol-functionalized ionic liquids merged the physical and chemical properties of ionic liquids and polyethylene glycol, so it can be used as better solvent or reaction medium than that of ionic liquids or polyethylene glycol respectively. On the other hand, the polyethylene glycol-functionalized ionic liquids could be easily modified with different functional groups, which can change the corresponding electronic properties by the modification of their structure. All this will contribute greatly to improve the catalytic performance in polyethylene glycol-functionalized ionic liquids involved organic reactions. The previous progress showed that there are several merits for the application of polyethylene glycol ionic liquids in organic synthesis, not only improved the catalytic activity and selectivity of reaction, but also simplified the work-up, and facilitated the separation and reuse of traditional catalyst. The paper summarizes the synthesis of various polyethylene glycol functionalized ionic liquids, and focused on the recent applications of polyethylene glycol functionalized ionic liquids as new reaction medium, or catalyst in organic reaction, including addition reaction, condensation reaction, reduction reaction, esterification, nitration reaction, oxidation reaction, hydrolysis reaction, Heck reaction, Suzuki-Miyaura coupling reaction, etc.