Studies On The Selective Oxidation Of Organic Compound Catalyzed By 8-quinolinolato Vanadium, Iron And Manganese Complexes

Oxidation of cyclohexane, sulfoxidation of sulfides and epoxidation of cyclohexene are all important reactions in organic synthesis, because their products are very important fine chemical intermediates. Many kinds of catalysts, especially the transition metal complexes, have been applied widely to these selective oxidation reactions. Aqueous hydrogen peroxide is a particularly attractive oxidant since it is cheap, environmentally friendly, easy to handle and produces only water as a byproduct, which reduces purification requirements. So for industrial applications, the development of oxidation reaction with H2O2 using cheap metal complexes as catalysts is significant. This thesis is focused on the study about the selective oxidation of cyclohexene, cyclohexane and sulfides with H2O2 catalyzed by 8-quinolinolato Mn(Ⅲ), Fe(Ⅲ), and oxobis(8-quinolinolato)V(Ⅳ) complexes, respectively, and the major results are summarized as follows:1) A series of Oxobis(8-quinolinolato)V(Ⅳ) complexes were synthesized and characterized by FT-IR, UV-Vis, TG-DSC. The oxidation of cyclohexane was employed to assess the catalytic performances of these catalysts. The effects of various parameters and different ligand on this oxidation process were also investigated. When we used 0.4 mol% 5-Cl-Q2OVⅣas catalyst in acetonitrile at 75℃, n(substrate):n(H2O2)=1:1, the best results could be obtained in total yield of 20% of cyclohexanol and cyclohexanone for the oxidation of cyclohexane. The proposed reaction mechanism and interfnediate species were also studied by UV-Vis.2) A series of 8-quinolinolato iron(Ⅲ) complexes (Q3FeⅢ) were synthesized and characterized by FT-IR, UV-Vis, and chemical analysis methods. After a series of tests, we found that 8-quinolinolato iron could efficiently catalyze the oxidation of thioanisole with H2O2 in the absence of solvent under mild conditions. The effect of various parameters such as the reaction temperature, reaction time, catalyst's amount, and oxidant concentration were also studied. Based on the stepwise overlay of UV-vis spectra for the reaction mixture, we proposed a reasonable mechanism for this reaction:Q3FeⅢinteracts with H2O2 to form a Q3FeⅢ-OOH with a pendant hydroxyl group through opening one of the Fe-O bonds. Then, that specie may undergo a heterolytic cleavage of its O-OH bond to generate high-valent Q3FeⅣ=O intermediates. Finally, the intermediates may directly oxidize thioanisole to the oxidation products and simultaneously give the regenerated catalyst.3) We designed and synthesized a series of 8-quinolinolato manganese(Ⅲ) complexes supported on the cellulose tribenzoate. The influences of the substrate concentration and the volume ratio for solvent on the oxidation of cyclohexene were studied. The results show that these Q3MnⅢcomplexes can be supported on the cellulose tribenzoate well. Furthmore, these supported catalysts are very efficient for oxidation of cyclohexene as well as those Q3MnⅢcomplexes. The workup is simple and the catalyst can be recycled for several times.