Design And Preparation Of Supported Ionic Liquid And Its Catalytic Activity For The Conversion Of Aldehydes

Ionic liquids have been paid more attention as a green solvent because of their excellent physical and chemical properties such as good thermal stability,low vapor pressure and strong solubility.However,there are some disadvantages such as large amount of ionic liquid used in catalytic reaction system,and it is not easy to post-treatment.The heterogeneous of ionic liquid,i.e.loaded ionic liquid,solves this problem well.In this paper,a series of mesoporous ionic liquids were designed and prepared by grafting imidazole ionic liquids on the surface of silicon-based materials.A series of M-SBA-15@IL-BF₄ were prepared by grafting on the surface of mesoporous material M-SBA-15;FT-IR,UV Vis,XRD,SEM,N₂ adsorption desorption,EDS,TG and other characterization methods were used to confirm the structure and performance of the catalyst.The results show that ionic liquids have been successfully loaded on mesoporous materials without affecting the pore characteristics of the carrier.In addition,the catalyst has high thermal stability.In the Hantzsch reaction with ethanol as solvent,the catalytic activities of a series of SBA-15 supported midazole ionic liquids M-SBA-15@IL-BF₄ were investigated.The catalyst has good catalytic performance in the synthesis of 1,4-dihydropyridine at room temperature,especially the Ti-SBA-15@IL-BF₄,which is supported by the mesoporous material,shows the synergistic effect of the titanium site of the mesoporous material and the acid site of the ionic liquid,and has the best catalytic effect.Under optimal conditions,all kinds of aldehydes have high conversion efficiency.The circulation experiment of catalyst shows that M-SBA-15@IL-BF₄ can be effectively reused for 5 times without significant decrease in activity.A series of PMO supported benzotriazole ionic liquids（PMO-IL-anion）were investigated in the synthesis of trisubstituted imidazole in ethanol.Among them,PMO-IL-BF₄（1.0）has the best catalytic performance,which may be due to the synergistic catalysis of the basic site and mesoporous support.In the optimal reaction conditions and catalytic system,the reaction yield can reach 82%-92%.In addition,the catalyst can be reused five times without obvious activity reduction.The new supported ionic liquid designed above has the advantages of both homogeneous and heterogeneous catalytic systems:It can make it well separated from the product,and will not pollute the environment,at the same time of using ionic liquid more efficiently,which provides a new idea for industrial catalytic synthesis.