Study On Catalytic Styrene Oxidation By Iron Corroles

As catalysts, iron corroles complexes have potential applications in many organic reactions. So far, the reports about iron corrole catalytic oxidation reactions are rare, and the reaction mechanisms are ambiguous.In the field of catalytic oxidation reaction, iodosylbenzene(Ph IO), m-chloroperbenzoic acid(m-CPBA), and tert-butyl hydroperoxide(TBHP) can be employed as an oxygen source, reaction also involves various organic substrates. It was found that substrate and oxidant have great influence on catalytic oxidation. Four iron(IV) corroles that differ in their electronic environments based on meso-substitution by pentafluorophenyl and phenyl groups were synthesized and characterized. Their effects on the activity of catalytic oxidation of styrene in different systems(solvent、oxidant、axial ligand) was investigated. The corresponding reaction mechanisms were discussed. The main content of this work is as follows:1. Four meso-substituted iron(IV) corroles having different number of pentafluorophenyl or phenyl groups and corresponding iron corrole complexes were synthesized and characterized by spectroscopic techniques(UV-visible, mass spectrometry and nuclear magnetic resonance). Uv-vis spectrum experimental results indicated that the iron corrole maintain trivalent in DMF, while tetravalent oxidation state within 48 h in CH3 CN. The tetravalent iron corrole convert to trivalent iron corrole with time in DCM、DMAc and toluene other solventswithin 48 h. Four iron corrole complexes also exhibit different electrochemical properties DMF and CH3 CN.2. Catalytic oxidation activity by these iron corroles using different oxidants were studied in DMF and CH3 CN, respectively; The effect of axial ligand imidazole on the oxidation product distribution when usingdifferent oxidants in CH3 CN was also investigated. In CH3 CN, experiment results indicate that benzaldehyde is the major product using TBHP, the more electron deficient iron corrole exhibit the higher catalytic activity. Styrene epoxide is major product when use m-CPBA as oxidant in CH3 CN, and the less electron deficient iron corrole exhibit the higher catalytic activity. When the oxidant is Ph IO, the major product is Styrene epoxide, the catalytic activity order is: F0C-Fe>F15C-Fe>F5C-Fe>F10C-Fe. While when the oxidant is Hydrogen peroxide(H2O2) or oxone: H3K5O18S4(KHSO5 is the active ingredient, molar ratio of KHSO5 : KHSO4 : K2SO4 is 2 : 1 : 1), iron corrole hardly catalyze oxidation styrene.The study also indicated that the axial coordination of F15C-Fe by imidazole gives 1:2 complexes and the association constants is large. Also, axial ligandimidazole has different effect on the oxidation product distribution when using different oxidants.3. In DMF, the catalytic activity order for the four iron corrole is the same as the order in CH3 CN in the presence of m-CPBA,but the overall catalytic activity is lower than that of CH3 CN. When the oxidant is KHSO5, iron corrole can catalyze oxidation styrene in spite of the yields aren’t high, that differs in CH3 CN. The differences for catalytic activity in different reactive systems suggest the catalytic mechanism depend on the reactive system.