Knoevenagel冷凝
催化作用
丙二腈
金属有机骨架
化学
苯甲醛
多相催化
氰基乙酸乙酯
表面改性
醛
金属
有机化学
缩合反应
吸附
组合化学
高分子化学
物理化学
作者
Martin Hartmann,Marcus Fischer
标识
DOI:10.1016/j.micromeso.2012.06.044
摘要
Metal–organic framework (MOF) materials have only been scarcely explored for applications in heterogeneous catalysis in recent years. In addition to the use of MOFs as supports for the deposition of highly dispersed metal particles, the incorporation of active centers such as coordinatively unsaturated metal sites and the functionalization of the organic linkers with acidic or basic groups seem to be most promising. In our contribution, three different MOFs carrying amino groups at their organic linkers, namely Fe-MIL-101-NH2 (SBET = 3438 m2 g−1), Al-MIL-101-NH2 (SBET = 3099 m2 g−1) and CAU-1 (SBET = 1492 m2 g−1), were synthesized and tested in the Knoevenagel condensation of benzaldehyde with malononitrile and with ethyl cyanoacetate, respectively. It is shown that the expected products benzylidenemalononitrile (BzMN) and ethyl α-cyanocinnamate (EtCC) are formed with selectivities exceeding 99% and yields of 90 to 95% after 3 h (for BzMN). Due to the very small pore windows of CAU-1 (0.3 to 0.4 nm) the reaction proceeds much slower over this catalyst in comparison to the amino-MIL-101 derivatives, which possess open pore windows of up to 1.6 nm. Moreover, the catalyst Al-MIL-101-NH2 is recyclable without significant loss of activity.
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