Synthesis And Catalysis Research Of Hollow Porous Organic Nanospheres Modified By Tetratriphenylphosphine Palladium

In recent years,organic porous materials have attracted more and more attention from scientists due to their large pore volume and specific surface area,low skeleton density,and excellent chemical modifiability.There are potential applications in the fields of sensing,optoelectronics,drug release,and heterogeneous catalysis.Although there are a lot of researches on the application of organic porous materials at present,due to the variety of organic porous materials and the various modification strategies,there is still a lot of research and development space for organic porous materials.For example,how to simply and efficiently support precious metals on organic porous materials and make them effectively use the rich advantages of controllable multi-stage pores of organic porous materials to have more efficient applications in the field of homogeneous and heterogeneous catalysis is still a challenging subject.This article is divided into three chapters.The first chapter,as an introduction,mainly introduces various organic porous materials and their applications,related backgrounds in the field of organometallic catalysts and homogeneous and heterogeneous catalysis.The second chapter proposes a synthesis strategy of supporting small-molecule organometallic catalysts on organic porous polymers in one step by co-hyper-crosslinking mediated self-assembly strategy.In this chapter,the hollow porous organic nanospheres modified by tetratriphenylphosphine palladium?H-PONs-Pd?PPh₃?₄?was synthesized through a Scholl hyper-crosslinking reaction in chloroform by taking a polylactic acid-b-polystyrene?PLA-b-PS?diblock polymer and a small-molecule organometallic catalyst,tetratriphenylphosphine palladium as a precursor.,and H-PONs-Pd?PPh₃?₄?1/15?was characterized by FT-IR,XPS,ICP,TEM,BET and other characterization methods)structure and properties.Experimental results show that when controlling tetraphenylphosphine palladium in appropriate proportions the catalyst H-PONs-Pd?PPh₃?₄?1/15?obtained in the final synthesis has a hollow porous spherical structure with a specific BET surface area of 587.5m²/g,a pore volume of1.96m³/g,and a palladium content of 1.8wt%.Subsequently Suzuki-Miyaura coupling reaction using chlorobenzene and phenylboronic acid as substrates proved that the synthesized catalyst H-PONs-Pd?PPh₃?₄?1/15?has a high catalytic activity.After 10cycles,it still has a high conversion rate?93%?,which proves that the catalyst has good stability.In addition,the reaction between different substituents and halogenated substrates at different substitution positions with phenylboronic acid proves that the obtained supported catalyst has excellent universality.The third chapter studies the preparation of hollow porous organic nanospheres as nanoreactor-encapsulated tetratriphenylphosphine palladium and their subsequent application in catalytic coupling reactions.First,a polylactic acid-b-polystyrene?PLA-b-PS?diblock copolymer was used as a precursor,and an organic porous polymer with a hollow sphere network structure was obtained through a F-C hyper-crosslinking reaction.Then,the triphenylphosphine and palladium chloride were reacted in the cavity of a hollow porous organic nanosphere nanoreactor through the diffusion of solvent,and then reduced by hydrazine hydrate to obtain hollow porous organic nanospheres nanoreactor-encapsulated tetratriphenylphosphine palladium hollow porous organic nanosphere catalyst material?Pd?PPh₃?₄@H-PONs?.And it was characterized by FT-IR?XPS?ICP?TEM?BET tests.It proves that the synthesized Pd?PPh₃?₄ was successfully encapsulated in the cavities of hollow sphere network structure,and the content of palladium is 1.38 wt%.Subsequently Suzuki-Miyaura coupling and Heck coupling tests were used as model reactions to characterize the catalytic activity of Pd?PPh₃?₄@H-PONs.It was found that at 1h and 3h respectively,the substrate conversion rate reached more than 99%,these phenomenon show that Pd?PPh₃?₄ in the cavities of H-PONs still have high catalytic activity,further leak tests and 10 cycle tests confirm that the obtained catalyst has excellent cycle stability.