Study On The Phase Transfer Catalytic Epoxidation Of Cyclohexene Oxidized By H₂O₂

This dissertation was financially supported by Henan Province Elitist Innovation Fund. In this work, H2O2 with ample supply in China was used as oxidant in the epoxidation of cyclohexene. And we mainly carried out the following aspects of research works:1. A series of quaternary ammonium salts of heteropolyacids with different effective number of C atoms have been synthesized from olybdophphosphoric HPA or phosphorictungtic HPA with Keggin structure and different quaternary ammonium. These quaternary ammonium salts of heteropolyacids were characterized by IR and elemental analysis and proved to keep the Keggin structure of heteropolyanion.2. These quaternary ammonium salts of heteropolyacids with different structure were used in the catalytic decomposition of H2O2 upon the Mo(VI) or W(VI) active components. It showed that the catalytic decomposition reactions of H2O2 were all of zero-order, and the conversion of H2O2 was lower than 4% in most cases.3. These quaternary ammonium salts of heteropolyacids were used in the catalytic epoxidation of cyclohexene oxidized by H2O2 to study their catalytic properties. It showed that the conversion of H2O2 was near to 100% and the selectivity was high as 80%.4. The key factors influencing the epoxidation were also studied, such as reaction time, temperature, mole ratio between cyclohexene and H2O2, the kinds and amount of catalysts, of cocatalyst, and those of solvent. To study the interaction among these factors, orthognol technique was used twice to optimize the reaction conditions. And the optimal synthesis conditions were detailed as: n(C6H10) : n(H2O2)=2.2 : 1 (based on 0.04 mol of H2O2) , temperature 35 C , reaction time 1.5 h; the best catalyst and cocatalyst were [(CH3)2(C18H37)(CH2Ph)N]3PW12O40 and quaternary ammonium salt B respectively, and with the amount of 0.96 g and 0.55 g in turn; solvent of chloroform 35 mL.The points of this work were listed as follows:1. The green oxidant H2O2 is used in this work with the reductive production of H2O. So there is no baneful materials to release and it can be ascribed to a kind of green progresss.2. The epoxidation was carried out by PTC, which solved parts of the technical problems, i.e. the hydrolyzation of epoxycyclohexane when oxidized by aqueous H202.3. A series of quaternary ammonium salts of heteropolyacids catalysts (including Mo series and W series) with different effective C atoms were systematically studied in the epoxidation of cyclohexene. And the difference in effective C atoms was used to explain the different catalytic properties among all catalysts, which was also used to guide the design and study of the relation between configurations and properties of these catalysts.