Synthesis Of Phosphine-containing Chitosan And Porous Organic Polymers And Application In Heterogeneous Reactions

Porous organic polymers not only have high porosity and specific surface area,but also have strong tunability and modifiability,which have wide application prospects in heterogeneous catalytic reaction systems.Porous organic polymers can support a series of metal compounds and the prepared supported metal catalyst has excellent stability,which play an important role in recovery and recycling of metals.In this paper,a series of porous organic polymers supported-catalysts were designed and synthesized for heterogeneous Suzuki coupling,olefin isomerization and alkyne Wacker oxidation reactions.1.In this paper,tri(4-vinyl)triphenylphosphine monomer was first used for the modification of the natural product chitosan.The phosphine-doped chitosan polymer(PPh₃?CS)was prepared and further was used for supporting Pd(OAc)₂to synthesize the corresponding chitosan-supported palladium catalyst containing phosphine ligand.Under mild conditions,Pd/PPh₃?CS can catalyze the Suzuki reaction of various halogenated aromatic hydrocarbons with arylboronic acids to obtain the corresponding biphenyl products in good yields(74-99%).The heterogeneous catalyst can be easily separated from the reaction system and reused for at least four cycles.2.Using 4,4'-dibromobiphenyl as raw material,its lithium salt reacted with PCl₃to afford porous organic polymer POP-PPh₃.The metal-loaded porous organic polymers(Rh/POP-PPh₃)was prepared by the loading of Rh(acac)(CO)₂.Rh/POP-PPh₃exhibits high catalytic activities and good yields(79-99%)in the isomerization of terminal olefins to the corresponding internal olefins.By simple separation,Rh/POP-PPh₃can be recycled 5 times.3.A porous organic polymer(POP-POPh₃)was readily prepared by oxidation of POP-PPh₃with H₂O₂.After coordination with Pd Cl₂and Cu Br₂precursor,a Pd/Cu bimetal-loaded porous organic polymer(Pd/Cu@POP-POPh₃)was afforded.Both the Pd(II)and Cu(II)could coordinate with the P=O bonds in the polymer.Furthermore,the catalyst has high surface areas,hierarchical porosity and good thermostability.The Pd/Cu@POP-POPh₃catalyst was successfully used in heterogeneous oxidation of alkynes with O₂as the oxidant to afford corresponding 1,2-diketones in high to excellent yields(76-99%).A series of alkynes with various functional groups performed well in the process.The heterogeneous catalyst can be reused for five cycles without significant loss of catalytic activity in oxidation of diphenylacetylene.