Magnetic Nanomaterials For The Catalytic Synthesis Of Benzimidazole Compounds

Benzimidazole series compounds and their derivatives are important intermediates in the production of dyes,pesticides and pharmaceuticals,and they are widely used in these fields.The condensation of aniline compounds and aldehydes to obtain benzimidazole compounds is a very energy-saving,environmentally friendly,economical and efficient method.This synthesis method requires efficient catalysts.Therefore,the development of efficient benzimidazole synthesis catalysts is to establish mild conditions,The key to a high-yield synthesis system.In the existing research on benzimidazole,most of the homogeneous catalysts are used.Compared with homogeneous catalysts,heterogeneous catalysts have the advantages of simple separation and recyclability.And the introduction of magnetic separation technology into the catalyst can quickly and quickly enrich and separate the nano-catalyst,avoiding the loss of catalyst caused by traditional centrifugation,filtration and other methods.In this context,this paper synthesized UiO-66 coated Fe3O4 as a supported magnetic nanocatalyst,using N-phenyl o-phenylenediamine and benzaldehyde as raw materials,and ethanol as a solvent to study the synthesis of benzimidazole.Firstly,a magnetic Fe3O4(～200 nm)with uniform particle size was synthesized by solvothermal method.After activation,Fe3O4 nanospheres were coated with a layer of silicon dioxide by TEOS(Ethyl Orthosilicate)to form Fe3O4@SiO2.Then use solvothermal method to coat a layer of UiO-66 as the active center of the reaction.Using N-phenyl ophenylenediamine and benzaldehyde as model substrates,the activity of the catalyst was explored,and the optimal ratio of the catalyst was determined.The optimal reaction yield was 94%.Compared with the traditional synthesis method,the magnetic heterogeneous nano-catalyst is more convenient and safer to operate,and has high reaction activity.It is a very promising catalyst.A series of characterizations such as TEM,FT-IR,XRD,and BET have proved the successful synthesis of magnetic nanomaterials,and the substrate exploration has good universality for aniline and benzaldehyde with different substituents.In addition,the activity of the catalyst did not decrease significantly after being reused five times.This was because UiO-66 was well coated on the magnetic carrier,which avoided the loss of active components.The catalytic synthesis system has good application prospects because of its high catalytic efficiency,mild reaction conditions and environmental protection.