Synthesis and characterization of poly 2-(dimethyl amino) ethyl methacrylate/ZSM-5/KIT-6 as a novel bi-functional catalyst and its application in tandem reaction of deacetalization-Knovonagel condensation

Recently, synthetic organic chemists have paid great attention to the development ofOne-Pot , sequential organic reactions owing to their comparably higher efficiencies, increased cost and reduced waste materials.Acid–basebifunctional catalyst is a popular concept quoted from enzyme catalysis reactions that contain two types of active centers of acid and base in catalytic systems. These catalysts may act in a cooperative way to activate both electrophiles and nucleophiles centers in reactions.However, most of these catalysts are hybrid organic-inorganic siliceous material that was prepared by grafting of organosilane compounds into the silica surface[1].However, there are several problems with these routes due to the use of highly toxic raw materials, high process cost, and complicated preparation procedures. Surface modification by polymers is one of the most effective methods due to the wide variety of functional polymers and can create many of functional group as reactions sites.Hierarchical zeolite is a new kind of zeolites that improve the performance of zeolite by combination of crystallinemicroporous frameworksand mesoporous materials(high thermal/hydrothermal stability of zeolites and fast mass transportation path of the mesoporous materials)[2]. In this study, we prepared a novel acid base bi-functional catalyst by in-situ polymerization of 2-(dimethyl amino) ethyl methacrylate in the micro/meso pores of hierarchical ZSM-5 zeolitewith low cost and simple route. In the catalyst structure, mesoporous ZSM-5 was used as a support which contains strong acid sites and poly 2-(dimethyl amino) ethyl methacrylate was used as a species which contains basic sites.The physical and chemical properties of the catalyst were investigated using FT-IR, XRD, BET, SEM, TEM and TGA techniques.Activity of the catalyst was tested in cascade reaction of deacetalization-Knoevenagel condensation (Figure 1).Excellent yields in a mild reaction condition, short reaction time and aqueous media were obtained. In addition, the results showed that the stability of the catalyst was excellent and could be reused 6 times without much loss of activity in the reaction.