Abstract

To develop Ru-incorporated bentonite clay as a heterogeneous base catalyst for use in Knoevenagel condensation as an alternative to hazardous base catalysts like pyridine, piperidine, etc., we purify the naturally occurring bentonite clay and Ru³⁺ cation incorporated into its interlayers of bentonite clayto improve its porosity and to increase the surface area of bentonite clay. Purified bentonite and Ru-bentonite were characterized by FTIR, PXRD, HRTEM, SEM & EDS, BET surface area analysis, and TGA. Base activation was done to these clays and a comparative study of these clays as recyclable heterogeneous catalysts for Knoevenagel Condensation was undertaken in water as a solvent for the chemical transformation of 2,4-dichlorobenzaldehyde and 4-hydroxybenzaldehyde with ethyl cyanoacetateinto their corresponding α,β- unsaturated acids. The products were characterized by FTIR, ¹H NMR, and ¹³C NMR analyses. The essential key points of this reaction are mild reaction conditions, absence of hazardous chemicals as used in classical Knoevenagel condensation, reusability of the catalyst, and high yield percentage of the products.

中文翻译：

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钌膨润土催化取代苯甲醛与氰乙酸乙酯的 Green Knoevenagel 缩合反应

摘要

为了开发掺钌膨润土作为非均相碱催化剂，用于 Knoevenagel 缩合，以替代吡啶、哌啶等危险碱催化剂，我们纯化了天然存在的膨润土和掺入其膨润土夹层中的Ru ³⁺阳离子粘土以改善其孔隙率并增加膨润土的表面积。通过 FTIR、PXRD、HRTEM、SEM 和 EDS、BET 表面积分析和 TGA 对纯化膨润土和红膨润土进行了表征。对这些粘土进行了碱活化，并对这些粘土作为克诺文格尔缩合反应的可回收多相催化剂进行了比较研究，以水为溶剂，将 2,4-二氯苯甲醛和 4-羟基苯甲醛与氰基乙酸乙酯化学转化为相应的 α,β - 不饱和酸。^{通过 FTIR、 1} H NMR 和¹³ C NMR 分析对产物进行了表征。该反应的关键点是反应条件温和、不含经典克诺文格尔缩合中使用的有害化学物质、催化剂的可重复使用性以及产品的高产率。