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991.
The kinetics of alkaline hydrolysis of 2‐chloro‐3,5‐dinitrobenzotrifluoride 1 and 1‐chloro‐2,4‐dinitrobenzene 2 were studied in various acetonitrile–water (AN–H2O) mixtures (10–90% w/w) at different temperatures. Thermodynamic parameters ΔH# and ΔS# show great variation, whereas ΔG# appears to vary little with the solvent composition presumably due to compensating variations. The results are discussed in terms of the solvent parameters such as preferential solvation, dielectric constant, polarity/polarizability, and hydrogen bond donor and acceptor parameters. It has been found that the factors controlling the reaction rates are the desolvation of OH?, the solvophobicity of the medium, and free water molecules in rich AN mixed solvent. The data showed that the solvatochromic parameters of (AN–H2O) mixed solvent are destroyed in the presence of excess OH?. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 453–463, 2010 相似文献
992.
Herein, one-pot synthesis of pyrimido[4,5-b]quinoline and indenopyrido[2,3-d]pyrimidine derivatives was developed by the three-component reaction of aldehydes, 6-amino-1,3-dimethyluracil, and 1,3-dicarbonyl compounds in the presence of glycolic acid-supported cobalt ferrite CoFe2O4@SiO2@Si (CH2)3NHCOOCH2COOH as a novel magnetic catalyst in ethanol at reflux conditions. Glycolic acid-supported cobalt ferrite was characterized via Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). Moreover, the catalyst was easily recovered with magnetic separation and recycled at least for five times without significant loss of its catalytic activity. The products were formed in excellent yields over appropriate reaction times under environmentally friendly conditions. The high efficiency and easy isolation of catalyst from products with an external permanent magnet are some of the remarkable advantages of this method. 相似文献
993.
Khalil Faghihi 《中国化学快报》2010,21(1):13-17
<正>Six new polyesters 7a-f were synthesized through the solution polycondensation reaction of diacid chloride 5 with six aromatic diols 6a-f in N,N-dimethyl acetamide(DMAc) as solvent in the presence of pyridine as base.The polycondensation reaction produced a series of novel polyester containing pyridyl moiety in the main chain in high yields with inherent viscosities between 0.35 and 0.54 dL/g.The resulted polymers were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherent viscosity and solubility tests.Thermal properties of these polymers were investigated by using thermal gravimetric analysis(TGA) and differentional thermal gravimetric(DTG).The glass-transition temperatures of these polyesters were recorded between 130 and 170℃by differential scanning calorimetry(DSC) and the 10%weight loss temperatures were ranging from 390 to 450℃under nitrogen. 相似文献
994.
995.
Masoud Amirkhani Andrea Taschin Riccardo Cucini Paolo Bartolini Dino Leporini Renato Torre 《Journal of Polymer Science.Polymer Physics》2011,49(9):685-690
We investigated the acoustic and thermal features of a polymeric system by a heterodyne detected transient grating technique. We studied two polymers characterized by different molecular weights. Transient grating experiments could reveal a reliable series of information on sound velocity, acoustic damping time, and thermal diffusion of the polymers. The temperature and molecular weight dependence of the polymer acoustic and thermal properties are reported. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
996.
997.
Physics of the Solid State - Molecular dynamics simulation was employed in this study to investigate the atomistic mechanisms involved in the Ni–Al alloy homogeneous deformation and the... 相似文献
998.
The aim of this paper is to present separation theorems for two disjoint closed sets, without convexity condition. First, a separation theorem for a given closed cone and a point outside from this cone, is proved and then it is used to prove a separation theorem for two disjoint sets. Illustrative examples are provided to highlight the important aspects of these theorems. An application to optimization is also presented to prove optimality condition for a nonconvex optimization problem. 相似文献
999.
Abstract
A Mild and efficient method for preparing amides by reaction of nitriles with benzhydrol and tertiary alcohols is described using polyvinylpolypyrrolidone-supported boron trifluoride. Selective amidation of benzhydrol in the presence of primary benzyl alcohols was also achieved. 相似文献1000.
Dilawar Hassan Ali Talha Khalil Amber Rehana Solangi Ahmed El‐Mallul Zabta Khan Shinwari Malik Maaza 《应用有机金属化学》2019,33(8)
We report an eco‐friendly synthesis of α‐Cr2O3 nanoparticles (NPs) using Callistemon viminalis (Bottle Brush) flower extracts as an efficient reducing and capping agent. NPs of sizes 15 nm and 17 nm were synthesized by annealing them at 400°C and 500°C, respectively, which were characterized by X‐ray diffraction, UV–Vis, Fourier transform‐infrared, high‐resolution‐transmission electron microscopy/scanning electron microscopy, SAED, energy‐dispersive X‐ray spectroscopy and SQUID. Microplate‐based assay was used for examining antibacterial potential against 12 pathogenic bacterial strains, and their minimum inhibitory concentrations were calculated. MTT cytotoxic assay was accomplished on Leishmania tropica amastigotes and promastigotes, which revealed IC50 values of 44 μg/ml and 10.56 μg/ml, respectively. An IC50 value of 46.32 μg/ml was obtained for HepG2 cancer cells. Enzyme inhibition studies indicated good acetylcholinesterase, moderate butyrylcholinesterase and low alpha‐glucosidase inhibition. Hemolytic assay indicated hemocompatibility at low concentration. In addition, good DPPH radical scavenging and moderate reducing power and total antioxidant potential was revealed by α‐Cr2O3 NPs. 相似文献