排序方式: 共有14条查询结果,搜索用时 156 毫秒
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G.P. Romanelli D. Bennardi D.M. Ruiz G. Baronetti H.J. Thomas 《Tetrahedron letters》2004,45(48):8935-8939
Substituted coumarins are synthesized from phenols and β-ketoesters by the Pechmann reaction, using a Wells-Dawson heteropolyacid (H6P2W18O62·24H2O) as catalyst by a solvent-free procedure. This one requires low reaction times, 130 °C temperature and as little as 1 mol % of Wells-Dawson acid, obtaining good to excellent yields of coumarins. The catalyst showed to be reusable with no differences in the yields. The results are compared with those of the reactions performed in toluene solution. The presented synthetic procedure is a convenient, clean and fast alternative for synthesizing 4-substituted coumarins (17 examples). 相似文献
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The multicomponent condensation of an aryl aldehyde,acetyl chloride,acetonitrile,and enolizable ketone as one-pot synthesis of β-acetamido ketones in high yields was investigated using commercial,non-corrosive,and environmentally benign Keggin and Wells-Dawson heteropolyacid catalysts.The best catalyst was H5PW10V2O40.The methodology used simple experimental conditions,and the short reaction times and high yields indicate it is a useful strategy for the large scale synthesis of β-acetamido ketones. 相似文献
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Laura M. SanchezÁngel G. Sathicq Jorge L. JiosGraciela T. Baronetti Horacio J. ThomasGustavo P. Romanelli 《Tetrahedron letters》2011,52(34):4412-4416
Wells-Dawson heteropolyacids (H6P2W18O62·24H2O) were used as catalysts in the Hantzsch-like multicomponent condensation reaction with 3-formylchromones as aldehyde component, a β-ketoester and ammonium acetate, under solvent-free conditions at 80 °C. Although the desired products were obtained, functionalized pyridines were the main reaction product and became the alternative route to dihydropyridine ring formation. Based on the proposed mechanisms for the formation of each of the obtained products, the multicomponent reaction was modified to afford only the functionalized pyridines (60-99%). Our procedure represents a clean alternative for the synthesis of several highly functionalized pyridines. 相似文献
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在水热条件下,通过Wells-Dawson型多酸[As_2W_(18)O_(62)]6-、氯化铜(CuCl_2·2H_2O)和5-(4-吡啶基)-1H-四氮唑(4-ptz)的反应,在同一反应釜中合成出2个结构完全不同的、都包含三核铜簇的多酸基化合物[Cu3(4-ptz)4(H_2O)7(As_2W_(18)O_(62))]·42H_2O(1)和[Cu3(4-ptz)5(H_2O)5(As_2W_(18)O_(62))]·47H_2O(2);当我们以另一种Wells-Dawson型多酸[P_2W_(18)O_(62)]6-、氯化铜(CuCl_2·2H_2O)和5-(3-吡啶基)-1H-四氮唑(3-ptz)反应,获得了另一种多酸基三核铜簇化合物[Cu3(3-ptz)4(H_2O)8(P_2W_(18)O_(62))]·33H_2O(3)。X射线单晶衍射结果表明,化合物1为多酸单支撑三核铜簇的悬臂式结构,化合物2的多阴离子被三核铜簇交替连接形成一维链式结构,而化合物3为多阴离子和三核铜簇形成的孤立结构。吡啶-四氮唑类配体(3-ptz和4-ptz)是形成化合物1~3中三核铜簇的重要结构因素。同时,研究了3个化合物的电化学以及光催化性能。 相似文献
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《Journal of Coordination Chemistry》2012,65(13):2122-2131
An organic-inorganic hybrid compound constructed from Wells-Dawson polyanion clusters and metal-organic complex subunits, [Cu(phen)3][Cu(phen)2Cu(phen)2(P2W18O62)]·2H2O (1) has been prepared hydrothermally and characterized by elemental analysis, IR, UV, cyclic voltammetry (CV) and single-crystal X-ray diffraction. Crystal structural analysis indicates that two terminal oxygen atoms of the Wells-Dawson polyanion located in the “belt” site coordinate with Cu2+. Three Cu ions have different coordination environments: Cu1 and Cu2 are five-coordinate, while Cu3 is six-coordinate. The bisupporting polyoxoanions [Cu(phen)2Cu(phen)2(P2W18O62)]2? are polymerized into a 1D chain by hydrogen bonding interactions, then the chains are stacked into a two-dimensional structure via offset, face-to-face, π ··· π stacking interactions. CV reveals that 1 exhibits three chemically-reversible processes. 相似文献
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Chang Liu Mingqi Xu Zenglong Tan Si Li Yu Wang Yunliang Wang Jingquan Sha 《无机化学与普通化学杂志》2020,646(11-12):489-494
A new Wells-Dawson polyoxometalates (POMs) based crystal supramolecular compound modified by flexible organic molecule bix, (H2bix)3(P2W18O62) · H2O (bixP2W18), [bix = 1,4-bis(imidazol-1-ylmethyl)benzene], was synthesized, characterized and explored as electrochemical biosensor to detect uric acid (UA) for the first time. Under optimized conditions, the bixP2W18 based sensor shows acceptable analytical performances for UA in terms of good linearity in the concentration range from 2.5 × 10–7 to 6.99 × 10–4 M and the lower detection limit 5.85 × 10–7 M (S/N = 3). More important is that bixP2W18 based UA sensor exhibits excellent stability testified by the result of XRD and IR, reproducibility, high selectivity in the presence of ascorbic acid (AA), dopamine (DA) and anti-interference immunity than some other reported materials. The bixP2W18 based biosensor could be applied for the determination of UA in the human urine samples with satisfactory results. 相似文献
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三空缺杂多阴离子衍生物的合成与性质 总被引:3,自引:3,他引:0
合成了三空缺WellsDawson杂多阴离子的衍生物Na20[M2(X2W15O56)2].nH2O,其中X=P,As;M=Mn,Co,Cu,Zn,用红外光谱、可见光谱、极谱及元素分析对其进行了表征.用极谱法研究了这些化合物在水溶液中的稳定性和反应性,其极谱行为与单空缺阴离子2αP2W17O6110-相似,在4.2相似文献
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