Methyltrioxorhenium (MTO)-Catalyzed Epoxidation Of Olefins In Rhenium Ionic Liquids

MTO is widely acted as an organometallic catalysis with high catalytic activity and high selectivity, so it is an efficient catalyst for epoxidation of olefins. There was a system that MTO was catalyst, H₂O₂ or UHP was oxidant, CH₂Cl₂ and diethylether was organic solvent in traditional catalytic olefin epoxidation system. Although the system has a good yield, it has many disadvantages. For example, it is easy to generate vicinal diol, hard to separate reaction products, and will lead to environmental pollution. This study is aimed to overcome these problems by utilizing a highly active, environment-friendly reaction system—ionic liquids as a new alternative to conventional organic solvents.First of all, we has synthesized a series of Rhenium ionic liquids, and these kinds of ionic liquids have been characterize by IR, NMR, Raman etc, The results show theses ionic liquid are very pure.In the next place Rhenium ionic liquids can be as solvent as well as catalyst in epoxidation of cyclooctene. According to the results of orthogonal experiments, we can get the optimality conditions for epoxidation of olefins. The temperature is the most factor for epoxidation of cyclooctene. It can be better in the optimal temperature. There is no by-product in this system. Get the optimal conditions were: substrate was 1mmol, oxidant 2.5mmol, ionic liquid 0.6 mL, the temperature is 70℃.We also do the recycle ionic liquid in the best condition and then the results show that ionic liquid can be recycled. So this ionic liquid is better solvent.The last, To MTO as catalyst, UHP as oxidant, imidazole ionic liquid as a solvent of rhenium for styrene, 1-hexene, 1,4-cyclohexadiene catalytic epoxidation. According to the results of orthogonal experiments, we can get the optimality conditions for epoxidation of olefins. Optimal conditions:Styrene: The Catalyst is the most factor for epoxidation of Styrene. The ionic liquid is the least factor for epoxidation of Styrene. Under optimal conditions at room temperature, catalyst: substrate: oxidant = 2:100:250, that is, the substrate 1mmol, catalyst MTO 20μmol, oxidant UHP2.5mmol, solvent 0.6mL.1-hexene: The Catalyst is the most factor for epoxidation of 1-hexene. The oxidant is the second factor for epoxidation of 1-hexene. Under optimal conditions at room temperature, catalyst: substrate: oxidant = 2:100:200, that is, the substrate 1mmol, catalyst MTO 20μmol, oxidant UHP2.0mmol, solvent 0.6mL.1,4-cyclohexadiene: The Catalyst is the most factor for epoxidation of 1,4-cyclohexadiene. The ionic liquid is the least factor for epoxidation of 1,4-cyclohexadiene. Under optimal conditions at room temperature, catalyst: substrate: oxidant = 2:100:250, that is, the substrate 1mmol, catalyst MTO 20μmol, oxidant UHP2.5mmol, solvent 0.5mL.There are many advantages: high catalysis activity, easy to separate product, recycle this system as well as green environmental. There is no report that Rhenium ionic liquid for epoxidation of olefins at home and abroad.