Au/MOF催化剂的制备、表征及其催化三组分偶联反应

采用后合成共价修饰法和一锅法分别制备了催化剂IRMOF-3-SI-Au(PS)和IRMOF-3-SI-Au(OP),运用X射线衍射、红外光谱、热重-差热分析、透射电镜以及程序升温还原对催化剂进行了表征,探索了这两种催化剂在醛、炔和胺三组分偶联反应中的催化性能,并推测了可能的反应机理.结果表明,两种催化剂对醛、炔和胺三组分偶联反应均具有较高的催化活性,产物炔丙基胺类选择性为100%,且可循环使用;结晶度较低的IRMOF-3-SI-Au(PS)的活性高于结晶度较高的IRMOF-3-SI-Au(OP);催化剂对芳香醛和脂肪醛以及环状胺均具有较高的催化活性,且对带有吸电子基团的芳香醛的活性高于带有供电子基团的.

Preparation and Characterization of Metal-Organic Framework Supported Gold Catalysts and Their Catalytic Performance for Three-Component Coupling Reaction

IRMOF-3-SI-Au(PS) and IRMOF-3-SI-Au(OP) catalysts were synthesized by post-synthesis method(PS) and one-pot method(OP),respectively.The catalysts were characterized by X-ray diffraction,infrared spectroscopy,thermogravimetric analysis and differential thermal,transmission electron microscopy,and temperature-programmed reduction.These two catalysts were tested by three-component coupling reaction of aldehydes,alkynes,and amines.The substrate scope,catalyst reusability,and possible mechanism were investigated.Both two catalysts showed higher conversions of benzaldehyde and 100% selectivity for propargylamines.Compared with IRMOF-SI-Au(OP),IRMOF-SI-Au(PS) gave a higher aldehyde consumption rate at 120 oC(13.7 vs 2.0 mmol/(g.h)) based on total gold content.Both aromatic and aliphatic aldehydes including those bearing functional groups,such as alkoxy,alkyl,and chloro-group,were able to undergo the corresponding three-component-coupling.It was found that aryl aldehydes possessing electron-drawing group afforded higher conversion than that with an electron-donating group bound to the benzene ring.Among the various amines tested,alicyclic amines,such as piperidine,pyrolidine,and morpholine,gave high conversions of benzaldehyde,whereas the diethylamine afforded lower conversion of benzaldehyde.The catalysts could be reused for three reaction cycles with only slight drop in activity.A tentative mechanism was proposed involving the activation of the C-H bond of alkyne by IRMOF-3 immobilized gold catalysts.