Catalytic Epoxidation Of Functionalized Olefins With30%H₂O₂

The epoxidation of alkenes has been an important subject, because epoxide compounds are very important intermediates in oil chemistry, organic synthesis, and fundamental chemistry. Now, there are two major routes to produce epoxides, one of which uses hypochlorous acid (or analogous compounds) as the oxidant, the other applies organic peracids. However, those agents are hazardous to the environment, so that researchers have attempted to seek new methods for the synthesis of epoxides. For example, aqueous hydrogen peroxide (30%) is a green oxidant for the epoxidation of alkenes, to produce water as the only byproduct.In this thesis, we concentrated researches on the conditions of epoxidation of alkenes under the assistance of nano-sized silica. Furthermore, the reaction conditions were properly optimized. It was observed that the addition of silica with a high BET surface area was generally beneficial to the epoxidation of alkenes with high conversions. For example, for the substrate of trans-2-hexenol, the conversions within4h were10.1mol%without silica and98.4mol%with silica, respectively. Also, some porous silica-based molecular sieves were used to catalyze the epoxidation of alkenes with30%H2O2to achieve good results comparable to the addition of silicon dioxide.Especially, the epoxidation of styrene with30%H2O2was carefully investigated. The reactions were run in a tightly-sealed autoclave and in an open two-necked flask. Also, the influences of reaction temperature, dosage of hydrogen peroxide, reaction time and various solvents were studied. The optimal conditions were temperature of60℃and molar ratio of hydrogen peroxide/styrene=1.3.