酸性沸石HBeta催化的傅克烯基化反应

Acidic Zeolite HBeta Catalyzed Friedel-Crafts Alkenylation Reaction

用酸性沸石HBeta在温和条件下实现了多种炔烃和富电子芳烃的傅克烯基化反应.HBeta具有的路易斯酸性位点(LAS)和布朗斯特酸性位点(BAS)分别是炔烃吸附活化位点和质子化位点.初步研究证明该反应通过一个BAS促进的烯基阳离子过程进行.烯基阳离子和BAS之间的相互作用较强,使得高活性的烯基阳离子不能发生聚合反应,避免了低聚副产物的生成.HBeta作为一种非均相催化剂,在炔烃烯基化反应中表现出了优异的重复性,可至少循环使用5次而没有明显的活性损失.最后,根据实验结果提出了HBeta催化炔烃烯基化的反应机理.

The Friedel-Crafts alkenylation of various alkynes and electron-rich arenes was achieved under mild conditions by using acidic zeolite Hbeta as catalyst.HBeta possesses Lewis acid sites(LAS)and Bronsted acid sites(BAS),which are adsorption activation sites and protonation sites for alkynes,respectively.Preliminary studies have shown that the reaction proceeds through a BAS-promoted alkenyl cation process.The strong interaction between the alkenyl cation and BAS prevents the highly reactive alkenyl cation from polymerizing,avoiding the formation of oligomerized by-products.HBeta,as a heterogeneous catalyst,showed excellent reproducibility in the alkyne alkenylation reaction and could be recycled at least 5 times without significant loss of activity.Finally,according to the experimental results,the reaction mechanism of HBeta-catalyzed alkyne alkenylation was proposed.