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951.
Nitriles were prepared from alkyl and aryl carboxylic acids in dry media conditions, under microwave irradiation. Heating of the carboxylic acid, urea and amidosulfonic acid adsorbed on alumina support in a microwave oven affords nitriles in 20–93% yields. 相似文献
952.
Under stannic chloride catalysis, trans-2-diethylphosphoryloxy-1,3-pentadiene (1) undergoes Diels-Alder reaction regio- and stereoselectively with a variety of α,β-unsaturated ketones at low temperature. 相似文献
953.
Abstract A series of enantiomerically pure (Z)-(?)-4-(1′-alkyloxy-1′-alkyloxycarbonyl-methylidene)-5(R)-[(1R)-menthyloxy]-γ-butyrolactones were synthesized and characterized in good to excellent yields via O-alkylation of (4R,5R)-(?)-4-ethoxyoxalyl-5-[(1R)-menthyloxy]-γ-butyrolactone with alkyl halides in the presence of K2CO3 in acetone at room temperature. 相似文献
954.
A short, practical, and efficient preparation of 2-(indol-3-yl)pyridine derivatives via a one-pot procedure of 3-cyanoacetylindole, chalcones, and ammonium acetate under microwave irradiation was described. All these compounds were obtained in good yield, and their structures were confirmed by 1H NMR, infrared, and elementary analysis. 相似文献
955.
A series of 5‐benzylidenerhodamine derivatives were synthesized by the cross‐aldol condensation of an aromatic aldehyde with rhodamine or rhodamine acetic acid in sodium acetate/acetic acid under microwave irradiation. The reaction was completed in 8–20 min with 63–94% yields and was environmentally benign with easy workup. 相似文献
956.
Ying Liu Ying‐Hui Yu Yi‐Fu Liu Guang‐Feng Hou Xiao‐Dan Wang Bo Wen Jin‐Sheng Gao 《无机化学与普通化学杂志》2013,639(1):193-196
The cage‐like complex, Ag4L4(NO3)4 ( 1 ) [L = 1, 4‐bis(pyridine‐2‐ylmethoxy)benzene] was synthesized by the reaction of the flexible bidentate ligand and silver nitrate. It was characterized by elemental analysis, IR spectroscopy, TG, and single‐crystal X‐ray analysis. Complex 1 is reported as the first cage‐like cluster constructed by four nitrate anions bridging two [2+2] macrocycles. A blue luminescent emission and luminescent enhancement effect are observed in complex 1 . 相似文献
957.
Ya Gao Nan Chen Weiwu Hu Chuanping Feng Baogang Zhang Qian Ning Bin Xu 《Journal of solution chemistry》2013,42(4):691-704
Adsorption is an effective treatment process for removing phosphorus and thus controlling eutrophication. In this study, a clay composite material called Al–dolomite–montmorillonite (Al–DM) was prepared and characterized. Al–DM performed well with respect to phosphate removal, with its performance depending on the Al–DM loading, contact time, initial phosphorus concentration and initial solution pH. Adsorption mechanisms were investigated by conducting batch tests on phosphate adsorption using the Al–DM. The adsorption process fitted both the pseudo-second-order kinetics model and the intra-particle diffusion model. The Langmuir, Freundlich and BET models all adequately described the adsorption isotherm data. Thermodynamic studies showed that the adsorption process was endothermic and spontaneous in nature. Al–DM is an effective adsorbent for phosphate removal mainly due to its hierarchical porous structures as shown by characterization with SEM and EDS. Chemical changes occurring before and after adsorption in a water environment indicated that Al–DM had little negative effect on water quality. 相似文献
958.
Quinoline bridged imidazolium precursors 5,8‐bis(N‐R‐imidazolylidenylmethylene)quinoline PF6– salts [H2L](PF6)2 [R = Me ( 1a ), R = naphthylmethyl ( 1b )] were prepared by quaternization of N‐methylimidazole and N‐naphthylmethylimidazole with 5,8‐bis(bromomethyl)quinoline, respectively. Reaction of the imidazolium ligands 1a and 1b with Hg(OAc)2 and Ag2O in acetonitrile gave the macrocyclic transition metal carbene complexes [Hg2L2](PF6)4 ( 2a and 2b ) and [Ag2L2](PF6)2 ( 3a and 3b ), respectively. All the N‐heterocyclic carbene complexes were characterized in detail by NMR, ESI‐MS, and elemental analysis. Structures of complexes 2a and 3a were determined by X‐ray diffraction studies. Structural studies revealed that the coordination arrangement of the central mercury atom in complex 2a displays a tricoordinate mode and the molecular conformation results in a“closed” form with the bridging quinoline functionality in the macrocycle, whereas the silver complex 3a does not show an coordiantion between the bridging quinoline and the AgI ion, which results in an “open” conformation of the macrocycle. The HgII and AgI NHC complexes showed similar UV absorption and luminescence in acetonitrile solutions. 相似文献
959.
Xiao‐Feng Guo Hui‐Ying Chen Xiao‐Hai Zhou Hong Wang Hua‐Shan Zhang 《Electrophoresis》2013,34(24):3287-3292
A simple and economical CE method has been developed for the analysis of four model basic proteins by employing N‐methyl‐2‐pyrrolidonium methyl sulfonate ionic liquid (IL) as the dynamic coating material based on the interaction of both between electrostatic attraction and hydrogen bond, and between the organic cations of IL and the inner surface of bare fused‐silica capillary. The N‐methyl‐2‐pyrrolidonium‐based IL modified capillary not only generated a stable suppressed electroosmotic flow, but also effectively eliminated the wall adsorption of proteins. Several important parameters such as the IL concentration, pH values, and concentrations of the background electrolyte were optimized to improve the separation of basic proteins. Consequently, under the optimum separation conditions, a satisfied separation of basic proteins including lysozyme, cytochrome c, ribonuclease A, and α‐chymotrypsinogen A with theoretical plates ranging from 2.09 × 105 to 4.48 × 105 plates/m had been accomplished within 15 min. The proposed method first illustrated the effect of hydrogen bond between coating material and inner capillary surface on the coating, which should be a new strategy to design and select more effective coating materials to form more stable coatings in CE. 相似文献
960.
Xin Feng Kelin Xia Zhan Chen Yiying Tong Guo‐Wei Wei 《Journal of computational chemistry》2013,34(24):2100-2120
Geometric modeling of biomolecules plays an essential role in the conceptualization of biolmolecular structure, function, dynamics, and transport. Qualitatively, geometric modeling offers a basis for molecular visualization, which is crucial for the understanding of molecular structure and interactions. Quantitatively, geometric modeling bridges the gap between molecular information, such as that from X‐ray, NMR, and cryo‐electron microscopy, and theoretical/mathematical models, such as molecular dynamics, the Poisson–Boltzmann equation, and the Nernst–Planck equation. In this work, we present a family of variational multiscale geometric models for macromolecular systems. Our models are able to combine multiresolution geometric modeling with multiscale electrostatic modeling in a unified variational framework. We discuss a suite of techniques for molecular surface generation, molecular surface meshing, molecular volumetric meshing, and the estimation of Hadwiger's functionals. Emphasis is given to the multiresolution representations of biomolecules and the associated multiscale electrostatic analyses as well as multiresolution curvature characterizations. The resulting fine resolution representations of a biomolecular system enable the detailed analysis of solvent–solute interaction, and ion channel dynamics, whereas our coarse resolution representations highlight the compatibility of protein‐ligand bindings and possibility of protein–protein interactions. © 2013 Wiley Periodicals, Inc. 相似文献