Porous cesium impregnated MgO (Cs–MgO) nanoflakes with excellent catalytic activity for highly selective rapid synthesis of flavanone

Abstract

Magnesium oxide (MgO) is an excellent base catalyst and its performance is well controlled by its morphology, surface area and surface structures. Here, a simple methodology for the synthesis of porous cesium impregnated MgO (Cs-MgO) nano flakes, with enhanced surface area (156 m 2 g 21 ), basic properties and improved catalytic activity for flavanone synthesis, is presented. The synthesis of Cs-MgO nano flakes is performed through impregnation of CsNO 3 on a nesquehonite [Mg(HCO 3 )OH?2H 2 O] rod, followed by calcination. During impregnation the metastable nesquehonite rod rehabilitated to hydromagnesite [4 MgCO 3 . Mg(OH) 2 ?4H 2 O] flakes. The flakes were porous, constructed by building blocks of small nanoparticles (10-25 nm) with a large number of edges and corners, step edges and step corners and numerous base sites of various strength (surface hydroxyl groups, low coordinate O 22 sites). It is observed that the amount of cesium in the MgO surface has a strong effect on its properties as well as its activity. The synthesized Cs-MgO nanoflakes showed significant improvement in the yield of flavanone through the Claisen-Schmidt condensation. A substantial increase in the reaction rate was also observed when DMF was used as a solvent without catalyst deactivation. As much as y90% conversion of 29-hydroxyacetophenone with y81% selectivity of flavanone was observed in just 15-20 min using the synthesized 0.5% Cs loaded MgO nanoflakes as a catalyst and DMF as a solvent. The improved catalytic activity of Cs-MgO as a catalyst and the promotion effect of DMF is discussed by studying the interaction of the substrate and the solvent on the catalyst surface and identification of intermediates formed on the catalyst surface under the reaction conditions using FT-IR.

Design and fabrication of mesoporous heterogeneous basic catalysts

“…[205][206][207] However, it is hard to build strongly basic sites on mesoporous silica through direct modification with alkali metal oxides. Dualcoating strategy.…”

Facile One-Pot Synthesis of Flavanones Using Tetramethylguanidinum-Based Ionic Liquids as Catalysts

“…In addition, we compared the catalytic performance of [TMG] with the results of other catalysts in the previous literatures [18][19][20][21][22][23][24][25] (Table 2). It was found that over-high temperature and too long reaction time were often taken to achieve a moderate catalytic performance.…”

Controllably oxidized copper flakes as multicomponent copper-based catalysts for the Rochow reaction

“…It can be seen that the M2 selectivity and Si conversion of Cu-p is 5.7 and 1.6%, respectively, while that of Cu-f increases to 54.0 and 16.3%, respectively. This is because the ake structure and higher surface area of Cu-f offer better contact between the catalysts and the Si powders, 11 which can improve the catalytic property. For Cu-Cu 2 O-f, the M2 selectivity and Si conversion rises up to 62.5 and 24.8%, respectively, and more importantly, Cu-Cu 2 O-CuO-f shows much increased values of 82.0 and 32.4% in the rst test (its values are reproducible during 3 tests), respectively, higher than those of Cu 2 O-CuO-f (80.1% M2 selectivity and 30.7% Si conversion).…”

“…The aky metals such as Al, 1 Ni, 2 Zn, 3 Au, 4 Cu, 5,6 and alloys, 7,8 which are generally produced by ball milling in industry, 1 are widely applied in electrode material, 5,9 pigments, 3,10 and catalysts. 11 This is because of their two-dimension structural characteristics, which endow these materials with some special properties, such as good adhesive ability, 10,12 excellent conductivity, 5,9 strong light reection 3,10 and commendable catalytic performance. 11,13 It is known that the catalytic performance of a heterogeneous catalyst is strongly affected by contact area between reactants and metal catalyst particles with a specic morphology and/or small particle size.…”

“…11 This is because of their two-dimension structural characteristics, which endow these materials with some special properties, such as good adhesive ability, 10,12 excellent conductivity, 5,9 strong light reection 3,10 and commendable catalytic performance. 11,13 It is known that the catalytic performance of a heterogeneous catalyst is strongly affected by contact area between reactants and metal catalyst particles with a specic morphology and/or small particle size. Compared with the bulk counterparts, the metal akes with even the same volume normally have much more active surface, thus conducive to catalysis.…”