Studys On Catalytic Application Of Vanadium Compound In Olefin Oxidation With Hydrogen Peroxide

The oxidation product of alkene is a kind of organic raw material and intermediate with very wide use , which is applied extensively in chemical industry. Hydrogen peroxide, as a green oxidant, has been attracted much attentions because water is the sole expected byproduct. However, the inherent oxidative activity and stability of hydrogen peroxide is relatively lower. Therefore, it has been of interest to find environmentally acceptable catalysts, which can activate its oxidative performances efficiently. In this thesis, oxidation of alkene includingβ-pinene, cyclohexene andβ-ionone were investigated catalyzed by vanadium pentoxide or organically caboxylate oxovanadium prepared from vanadium pentoxide using hydrogen peroxide as a oxidantOxidation ofβ-pinene catalyzed by vanadium pentoxide was carried out using aqueous hydrogen peroxide as a oxidant. The influences of conditon, such as reaction temperature, reaction time, catalyst amount, solvent amount, concentration of H₂O₂ and H₂O₂ amount, on the reaction were investigated. The optimal reaction conditions were: V（acetone） : V（β-pinene） = 4, m（V₂O₅）: m（β-pinene） = 1%, n（H₂O₂）: n（β-pinene） = 2, T=30℃and t=24 h. when reacted under this conditions, conversion ofβ-pinene reached up to 34% and nopinone、pinocarvone、myrtenal and carveol were obtained as the major products, the total selectivity 71 %. It is proposed that the oxidation of p-pinene catalyzed by vanadium peroxide involves a reversible V⁵⁺/V⁴⁺species redox cycle and the solvent acetone played a role as an oxygen transfer reagent.A series of organically caboxylate oxovanadium oxidation prepareded from vanadium pentoxide were used to catalyze oxidation of p-pinene. The influences of conditon, such as catalyst, catalyst amount, H₂O₂ amount, solvent amount and H₂O, on the reaction were investigated. The results showed that benzoic acid oxovanadium has better catalytic acitvity under mild conditions. Under the condition of V（acetone） : V（β-pinene） = 4, m[VO（PhCOO）₂] = 0.180 g, n（H₂O₂）: n（β-pinene） = 2, T = 30℃and t = 24 h, the conversion ofβ-pinene can reach up to 56% and selectivity of major products, nopinone and vebenone, were 78.33%. It seemed that VO（PhCOO）₂ can efficiently improve utilization percentage of H₂O₂.Oxidation of cyclohexene andβ-ionone with aqueous hydrogen peroxide as a oxidant catalyzed by citric acid oxovanadium, which was also synthesized form vanadium pentoxide, was successfully carried out under mild conditions. The reaction conditions, namely catalyst amount, reaction temperature, H₂O₂ amount, solvent amount and reaction time were investigated. The optimal reaction conditions were obtained :1. V（acetone） : V（cyclohexene） = 4, m（[VO（cit）]₂） : m （cyclohexene） = 110: 1,n（H₂O₂）: n（cyclohexene） = 3,T = 30℃, 24h. Under the optimal conditions, conversion of cyclohexene could reach up to 60% and selectivity of major products, cyclohexene-2-one and cyclohexene-2-ol, were 89.87 %. It is considered that because aqueous hydrogen peroxide （50%） is acidic solution, it promotes the hydrolysis of cyclohexene and the hydrogen bonds between organically caboxylate oxovanadium and H₂O₂ decrease the decomposing rate of H₂O₂.2. V（acetonitrile）: V（β-ionone） = 4, m（[VO（cit）]₂）: m （β-ionone） = 1%, n（H₂O₂） : n（β-ionone） = 4, T=50℃and t=24 h, conversion ofβ-ionone reached up to 58% and selectivity of major products, dihydroactinidiolide and 4-oxo-β-ionone, were 95.79%.