Molybdenum carbide as an efficient and durable catalyst for aqueous Knoevenagel condensation
作者:Mina Tavakolian、Mohammad Mahdi Najafpour
DOI:10.1039/c9nj04647j
日期:——
and benign catalysts were used for the Knoevenagelcondensation reaction. Among the compounds (Mo2C, MoS2, MoB, MoSi2), molybdenum carbide showed efficient performance for the Knoevenagelcondensation in aqueous media at room temperature, affording the corresponding products in high yields within a short reaction time. Notably, using this commercially available heterogeneous catalyst, the deaceta
a radical solvothermal polymerization method, we synthesized two porous organic polymersbased on Tröger's base (POP‐TB and POP‐Me‐TB) from the corresponding vinyl‐functionalized monomers (2,8‐divinyl‐6H,12H‐5,11‐methanodibenzo[b,f]diazocine and 2,8‐divinyl‐4,10‐dimethly‐6H,12H‐5,11‐ethanodibenzo[b,f]diazocine; v‐TB and v‐Me‐TB). The structure and porosity of these polymers are verified by using solid‐state
通过自由基溶剂热聚合方法,我们从相应的乙烯基官能化单体(2,8-二乙烯基-6 H,12 H- 5, 11-甲基二苯并[ b,f ]重氮电影和2,8-二乙烯基-4,10-二甲基-6 H,12 H -5,11-乙二苯并[ b,f ]重氮电影; v-TB和v-Me-TB 。通过使用固态NMR光谱,元素分析,SEM,TEM,N 2吸附等温线和CO 2验证了这些聚合物的结构和孔隙率吸附测试。它们具有较高的表面积和适中的孔体积,可提供较高的CO 2吸附能力(对于POP-TB和POP-Me-TB,在273 K时分别为90和71 mg g -1,在298 K时分别为60和44 mg g -1,分别在1 bar的CO 2压力下进行。此外,它们在基准Knoevenagel反应中具有出色的催化活性以及作为非均相催化剂的高度稳定性。
Critical assessment of the efficiency of chitosan biohydrogel beads as recyclable and heterogeneous organocatalyst for C–C bond formation
The effectiveness of neutral pH chitosan hydrogel beads (CSHB) as a green organocatalyst for a variety of CâC bond forming reactions (i.e. aldol reaction, Knoevenagel condensation, nitroaldol (Henry) reaction, Michael addition) has been comprehensively evaluated. Reaction rates, conversions and selectivities were studied as a function of a series of input variables including size, pH and reactive surface area of the beads, catalyst loading, temperature, molecular weight of the biopolymer, concentration, solvent system and molar ratio of reactants. Moreover, the catalytic biohydrogel beads were characterized by a variety of techniques including, among others, SEM, FT-IR, TGA and DSC.
1,7-octadiene derivatives 6a−k, in good to high yields. The reaction of certain imines 9 with 4 and 5a under similar conditions as above afforded the bis-allylated amines, N-allyl-N-3-butene-1-amine derivatives 10a−f, in good to high yields. The bis-allylation reactions most probably proceed through bis-π-allylpalladium intermediate 2. The above intermolecular bis-allylation was extended to the intramolecular
Knoevenagel and Wittig-Horner reactions in solid-liquid systems, with magnesium oxide or zinc oxide as catalyst. When Wittig-Horner reaction is competitive with Knoevenagel reaction, the catalyst can be modified to give a highly selective reaction ; the addition of dimethylsulfoxide on MgO or heiamethylphosphoric triamide on ZnO gives more efficient catalysts for the Wittig-Homer reaction. The addition of a small