Synthesis, Characterization And Catalytic Properties Of Metalloporphyrins Catalysts Immobilized On Montmorillonite

In organic chemical industry, selective oxidation of olefins to epoxides, sulfides to sulfoxides or sulfones, alcohols to carbonyl compounds are very important oxidation steps. Metallporphyrins, as biomimetic catalyst of cytochrome P-450, have been demonstrated with excellent catalytic activity and selectivity in the oxidation of various substrates. But the main disadvantages of metallporphyrins catalysts are instability and the difficulty for the recovery of the catalysts from the homogeneous phase system. Therefore, immobilizing of metalloporphyrins into insoluble solid as heterogeneous catalysts is gathering much attention in this research field.In this dissertation, cationic porphyrinato metal complexes were synthesized, and these complexes were immobilized between the montmorillonite layers by impregnation method. The synthesized heterogeneous catalysts were well characterized. Following, the epoxidation of alkenes, oxidations of compounds containing oxygen and sulfur to the corresponding products were developed by using the heterogeneous metalloporphyrins as catalysts under mild conditions, and the possible catalytic mechanisms were proposed for reactions.In the aerobic epoxidation of olefins to epoxides system, reaction conditions were well investigated using cyclohexene as model substrate. Cyclohexene could be converted to cyclohexene oxide with a yield of 91% under the optimized conditions, in which the amount of catalyst MnTM4PyP/MT was 0.02g, the solvent was acetonitrile, and reaction time was 2.5 h. The catalyst showed excellent recyclability, with the conversion of cyclohexene still over 80% when the catalyst was reused for three times. Various olefins, including cycloolefins, linear olefins and aromatic olefins could be converted to the corresponding epoxides with high yields in the catalytic system.In the aerobic oxidation of alcohols to carbonyl compounds system, reaction conditions were well investigated using benzyl alcohol as model substrate. Benzyl alcohol could be converted to benzylaldehyde with a yield of 89% under the optimized conditions, in which the catalyst was CoTM4PyP/MT, isobutylaldehyde was treble dose of substrate, reaction temperature was 70oC, the solvent was acetonitrile, and reaction time was 2h. Various alcohols, including aromatic alcohols, linear alcohols also could be converted to the corresponding carbonyl compounds under this condition within 2 h. The immobilized catalyst showed excellent recyclability, which no obvious decreasing conversion could be observed even after reuse for 5 times.In the selective oxidation of sulfides to sulfoxides system, reaction conditions were also well investigated using thioanisole oxidation as a model reaction. In experiment of thioanisole oxidation, the isolated yield of sulfoxide of 86% was obtained under the optimized conditions, in which the catalyst was MnTM4PyP/MT, the solvent was toluene, reaction temperature was 80oC, and reaction time was 45min. No obvious decrease could be observed after reuse for 3 times. Various sulfides also could be converted to the corresponding sulfoxide with high yields under mild conditions.