Ordered Mesoporous Ultrafine Organometallic Catalyzed Clean Organic Synthesis In Aqueous Media

Traditional homogeneous organometallic catalysts have high catalytic efficiency,but they are difficult to separate and recover from homogeneous phase,so they have great limitations in industrial application.In addition,volatile organic solvents in organic synthesis do great harm to human body.Compared with homogeneous organometal catalyst,the choice of organometal fixation has more advantages,however,there are still problems of low activity caused by shedding of active sites and destruction of microenvironment.Periodic mesoporous organic silicon(PMO)is a new kind of two-dimensional hexagonal mesoporous material.Its large specific surface area and uniform long channel structure facilitate the effective adsorption and diffusion of organic reactant molecules during mass transfer.The organometallic catalysts containing phosphine ligand form high negative electron center due to the strong electron donor effect of phosphine ligand,which effectively promotes electron transfer and thus has high activity.Based on previous research in the group,therefore,this article mainly uses the low temperature reduction of organic metal catalyst,building of ultrafine organic metal particles together phosphine ligands is strong to the electronic effect,make its form zero valent state of active site high negative center,promote the formation of electronic sites,and explore its application in water medium and the catalytic performance and mechanism of reaction.The main contents of this paper are as follows:(1)Firstly,(Pd Cl₂[PPh₂(CH₂)₂Si(OEt)₃]₂)was synthesized by using Pd(COD)Cl₂,PPh₂(CH₂)₂Si(OEt)₃)as metal source and phosphine ligand source respectively in toluene as solvent system after continuous stirring for 24 h at room temperature.Pd(II)-PPh₂-PMO(Et)was prepared by co-condensation of organosilane and(OEt)₃Si(CH₂)₂Si(OEt)₃ in one step by fully dissolving surfactant P123 under acidic conditions.Finally,Pd(II)-PPh₂-PMO(Et)was reduced to Pd(0)-PPh₂-PMO(Et)with0.2 mol/L Na BH₄ aqueous solution.(2)Au[PPh₂(CH₂)₂Si(OEt)₃]₃Cl was synthesized from(Au(tht)Cl and PPh₂(CH₂)₂Si(OEt)₃using anhydrous CH₂Cl₂as solvent.Au(I)-PPh₂-PMO(Et)was prepared by one pot co-condensation of surfactant P123,a certain amount of organometallic gold silane and(OEt)₃Si(CH₂)₂Si(OEt)₃ in 30 m L of 0.5 M HCl/H₂O solvent.Finally,Au(I)-PPh₂-PMO(Et)was reduced to Au(0)-PPh₂-PMO(Et)with0.2 mol/L Na BH₄ aqueous solution.The prepared catalyst also has a highly ordered two-dimensional hexagonal structure with large specific surface area and pore size,and the organic gold nanoparticles can be uniformly and orderly distributed in the long pore structure.In the hydration of aqueous alkynes,the efficiency is 99%and the activity is still good after 6 cycles.