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首页> 外文期刊>Catalysis science & technology >An efficient green protocol for the synthesis of tetra-substituted imidazoles catalyzed by zeolite BEA: effect of surface acidity and polarity of zeolite
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An efficient green protocol for the synthesis of tetra-substituted imidazoles catalyzed by zeolite BEA: effect of surface acidity and polarity of zeolite

机译：一个高效的绿色合成的协议tetra-substituted咪唑类沸石催化BEA:表面酸度和极性的影响沸石

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In the present study, the catalytic activity of various medium (H-ZSM-5) and large pore (H-BEA, H-Y, H-MOR) zeolites were studied as solid acid catalysts. The zeolite H-BEA is found to be an efficient catalyst for the synthesis of 1-benzyl-2,4,5-triphenyl-1H-imidazoles through one-pot, 4-component reaction (4-CR) between benzil, NH4OAc, substituted aromatic aldehydes and benzyl amine. The hydrophobicity, Si/Al ratio and acidic properties of zeolite BEA were well improved by controlled dealumination. The synthesized materials were characterized by various characterization techniques such as XRD, ICP-OES, BET, NH3-TPD, FT-IR, pyridine FT-IR, Al-27 and H-1 MAS NMR. It has been observed that the dealumination of the parent zeolite H-BEA (12) results in the enhanced strength of Bronsted acidity up to a certain Si/Al ratio which is attributed to the inductive effect of Lewis acidic EFAl species, leading to the higher activity of the zeolite BEA (15) catalyst towards the synthesis of 1-benzyl-2,4,5-triphenyl-1H-imidazoles under thermal solvent-free conditions with good to excellent yields. Using the present catalytic synthetic protocol, diverse tetra-substituted imidazoles, which are among the significant biologically active scaffolds, were synthesized in high yield within a shorter reaction time. The effect of polarity, surface acidity and extra framework Al species of the catalysts has been well demonstrated by means of pyridine FT-IR, and 27Al and 1H MAS NMR. The solvent-free synthetic protocol makes the process environmentally benign and economically viable.
机译：在目前的研究中,催化活性各种媒介(H-ZSM-5)和大孔隙(H-BEA,H-Y H-MOR)沸石作为固体酸进行了研究催化剂。高效的合成的催化剂1-benzyl-2 4 5-triphenyl-1H-imidazoles通过锅,4组件(4-CR)之间的反应苯偶酰、NH4OAc取代芳香醛和苄胺。和酸性沸石BEA的属性提高了dealumination控制。合成材料的特征XRD等各种表征技术ICP-OES,打赌,NH3-TPD FT-IR pyridine FT-IR,Al-27和h - MAS NMR。母公司的dealumination沸石H-BEA(12)导致布仑斯惕的增强实力酸度达到一定的Si /阿尔比归因于刘易斯的诱导效应酸性EFAl物种,导致越高沸石BEA的活动(15)对催化剂的合成1-benzyl-2 4 5-triphenyl-1H-imidazoles下热无溶剂条件良好优秀的收益率。tetra-substituted合成协议,多样化咪唑类,这是重要的生物活性支架,被合成在高收益率在一个较短的反应时间。极性效应、表面酸性和额外的框架Al物种的催化剂演示了通过吡啶的红外光谱,27艾尔·马斯和1 h NMR。协议使过程环保和经济上可行。

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