The Synthesis Of Ionic Liquid Supported Schiff-base Manganese Catalyst And Its Application On Catalytic Oxidation

Ionic liquid-supported metal catalysts have been applied in various reactions, including cyclization reaction, oxidation reaction, hydrogen transfer reaction, polymerization and coupling reaction. It has been widely studied in catalyzing asymmetric synthesis, especially in catalyzing epoxidation of olefins. To support Schiff-base complex on ionic compound, the catalyst can be recycled by simple washing with water. To further improve its catalytic activity and epoxidation selectivity, we choose acetylacetone and Cyclohexylenedinitrilo-tetraacetic as original reaction material. With multi-steps, we synthesized (salen)manganese catalyst supported by ionic liquid Mn-[salen-py][X]2and{Mn-[salen-py][Br]2}. The structure of the complexes were confirmed by a series of methods including elemental analysis, NMR, mass spectrometry, infrared spectroscopy, UV-Vis spectroscopy and so on. Further more, the complex’s catalytic performance were explored. Firstly, the influence of solvent, temperature and catalyst concentration on cyclohexene oxidation reaction were investigated with Mn-[Salen-Py][Br]2as catalyst and oxygen as oxidant. Under optimized reaction condition, the catalyst didn’t perform good enough as we expected before. The reason maybe that the molecular oxygen is relatively inert and a covalent bond is difficult to be broken into active oxygen. Thus the cyclohexene can not be easily oxidized, resulting in the low catalytic activity and epoxidation selectivity. Researches were further perfomed with hydrogen peroxide as oxidant. the influences of intiator concentration, solvent, temperature, catalyst concentration, hydrogen peroxide concentration and the counteranion of catalyst on the cyclohexene oxidation were investigated with Mn-[salen-py][X]2as the catalyst. The oxidation substrate extended to cycle and phenyl-substituted olefins and the catalytic activity did perform well in optimized reaction condition. Compared with other (salen)manganese catalyst, the complexes we synthesized not only have great catalytic activity and epoxidation selectivity, but also show good thermal stability. Therefore, the catalyst still kept its catalytic activity after five runs.The thesis mainly includs four parts:①An introduction on the reaction type catalyzed by ionic liquid-supported metal catalyst and relative progress in olefin oxidation using oxygen molecule and hydrogen peroxide as the oxidant.②Synthesis of target complex Mn-[salen-py][X]2and{-Mn-[Salen-Py][Br]2} by muti-steps and characterizing the structures, comparison the structures between chiral complex and non-chiral complex.③Exploring the catalytic activity of Mn-[Salen-Py][Br]2on cyclohexene oxidtation using oxygen molecule and hydrogen peroxide as the oxidant repectively, extending substrate scope under optimizing reaction condition and recycling the catalyst.④A summary of the experimental results and the future outlook of our work.