Study On The Preparation Of Pd/MIL-101 And The Formation Of Carbon-carbon?carbon-heteroatom Bond By Heterogeneous Catalysis

Objective:Our subject aims to develop novel Pd/MIL-101 heterogeneous catalysts to improve catalytic efficiency and develop some environmentally friendly heterogeneous catalytic reactions in aqueous phase,based on the idea of"green"organic chemistry and sustainable development.Method:1.Synthesis and characterization of MIL-101MIL-101 was synthesized by hydrothermal method,which crystal structures and purity were characterized by powder X-ray diffraction?PXRD?.Scanning electron microscopy?SEM?was used to investigate the morphology of materials.Their surface area and pore size were calculated by N₂ adsorption desorption experiments,and the stability of samples was studied by thermogravimetric analysis?TG?.Subsequently,the low boiling point solvent was used to exchange the water molecule in the micropore,and residual solvent was dried to remove low boiling solvent in the micropore.Finally,the stability of activated samples was confirmed by PXRD and TG experiments.2.Preparation and characterization of Pd/MIL-101The activated MIL-101 was soaked in a solution with palladium acetate.As a result,Pd²⁺/MIL-101 was obtained.Under the vacuum condition,Pd²⁺/MIL-101 was activated and subsequently the Pd/MIL-101 nanoparticles was obtained by NaBH₄reduction.The Pd/MIL-101 catalysts were characterized by inductive coupled plasma emission spectrometer?ICP?,BET surface area,powder X-ray diffraction?PXRD?,X-ray energy spectrum?EDS?,high resolution transmission electron microscope?HRTEM?,X-ray photoelectron spectroscopy?XPS?,respectively.The dispersion,morphology,particle size,content and valence state of Pd particles in the Pd/MIL-101were investigated in detail,which lay the foundation for further research on catalytic performance.3.Several organic reactions were catalysized by the Pd/MIL-101Heck,Sonogashira coupling and Wacker reaction are catalyzed by the Pd/MIL-101in aqueous phase.Furthermore,the Pd/MIL-101 was used to catalyze selective C₂arylation of N-methyl indole or benzofuran and the reaction of substituted2-aminophenol and isocyanitrile to produce benzoxazole derivatives.The products were characterized by GC-MS,¹H NMR and ¹³C NMR,respectively.The cycle use of the catalyst was investigated.After 5 runs of catalytic cycle,the metal loss of the catalyst was measured by ICP experiment,and the structure of the catalyst was characterized by TEM and PXRD experiment.Result:The Pd/MIL-101 was successfully prepared and characterized.The microstructure and morphology of the catalyst were characterized by XRD,XPS,SEM,HRTEM,ICP and N₂ adsorption respectively.The experimental results reveal that the Pd nanoparticles on the Pd/MIL-101 range from 1.5 nm to 2.5 nm,and the content of Pd nanoparticles is 1.5%.The Pd/MIL-101 acted an efficient heterogeneous catalyst to the following reactions.1.To catalyze halogenated benzene and ethylene of Heck reaction with 97%yield in the water phase,after 5 runs of catalysis,the catalyst can still maintain high reactivity.2.To catalyze halogenated benzene and alkyne of Sonogashira reaction with 89%yield in the water phase,after 5 runs of catalysis,the catalyst can still maintain high reactivity.3.In the water phase,using tert-butyl hydroperoxide as the oxidant styrenes of Wacker reaction,and the ketone was generated with the highest 86%yield,and the 5cycles of catalysis was realized.4.The selective C₂ arylation of N-methyl indole or benzofuran with halogenated benzene can produce indole and benzofuran derivatives.The highest yields are 88%and 87%,respectively,and 5 cycles of catalyst is achieved.5.The Pd/MIL-101 can catalyze the reaction of substituted 2-aminophenol and isocyanides to produce benzoxazole derivatives with the highest 94%yield,and the catalyst can be used for 5 runs.Conclusion:The MIL-101 was synthesized by hydrothermal method,and the Pd/MIL-101catalyst was prepared by supporting palladium nanoparticles on metal-organic frameworks?MOFs?MIL-101.The microstructure and morphology of the catalyst were characterized by XRD,XPS,SEM,HRTEM,ICP and N₂ adsorption respectively.Research shows that the Pd/MIL-101 as heterogeneous catalyst can catalyze Heck,Sonogashira coupling and Wacker reaction with high yields in aqueous phase.Furthermore,the Pd/MIL-101 was used to catalyze selective C₂arylation of N-methyl indole or benzofuran and the reaction of substituted2-aminophenol and isocyanitrile to produce benzoxazole derivatives.After 5 runs of catalysis,the catalyst can still maintain high reactivity,the Pd nanoparticles have almost no loss,which leads to these reactions are more green and economy.The formation of carbon-carbon bond and carbon-heteroatom bond are formed through the direct C-H activation.Nano Pd usually has good catalytic activity.It can be predicted that the Pd/MIL-101 will be widely applied in the field of heterogeneous catalysis.