| In recent years, supported catalyst has been paid more attention in thefield of chemical synthesis. This projects synthetic magneticmicrospheres of monodisperse and organic phosphine ligands bymembrane, palladium that as the active species of catalyst has beenbonded on the surfaces of the microcapsules by ligand exchange,ultimately, we have prepared stable palladium catalyst with someadvantages of homogeneous catalysis and heterogeneous catalysis. Thecatalysis has been applied to Heck reaction, we have determined its reusecondition and catalytic activity, it has provided experimental basis forpractical application of microcapsule-supported catalyst.We have composed4-styryl-diphenyl-phosphine monomer bymodified ethod in advance. Then this monomer, ferrofluid, initiator etc.have been dissolved in methylene chloride, this mixture was dispersionphase, we have prepared monodisperse magnetic microsphere by themethod of dispersion phase getting through SPG membrane intocontinuous phase in impressed pressure. We have analysised a number ofinfluence factors of shape and distribution of microcapsule, best prep-aration onditions: ethylene dichloride(10mL), monomer(SDPP)(0.5g),ferrofluid(1.5mL), divinyl benzene (DVB)(0.15mL) and azodiisobuty-ronitrile(AIBN)(0.10g). ontinuous phase was the aqueous solution ofsodium lauryl sulfate(SDS)(0.1%,w/v) and polyvinyl alcohol(PVA)(1.0%,w/v). the microballoon sphere has good monodispersity andconversion ratio of monomer was22.15%. Ultimately, we preparedmicrocapsule-supported palladium catalyst by getting the microcapsuleand tris(dibenzylideneacetone)dipalladium ligand exchange. Wedetermined P/Pd was4.265by inductively coupled plasma (ICP) anddetermined rate of zero-valence and bivalence palladium in the catalystby X-ray photoelectron spectrometer (XPS). The catalyst showed highstability and catalytic activity in the Heck reaction of bromobenzene andmethyacrylate, the yield of reaction was rather high by reusing12times. |
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