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101.
Synthesis of CuI Trifluoromethylselenates for Trifluoromethylselenolation of Aryl and Alkyl Halides 下载免费PDF全文
Chaohuang Chen Li Ouyang Quanfu Lin Yanpin Liu Chuanqi Hou Prof. Dr. Yaofeng Yuan Prof. Dr. Zhiqiang Weng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):657-661
The development of new strategies for synthesis of trifluoromethylthiolate compounds is of considerable importance in pharmaceuticals, agrochemicals, and advanced materials. Accordingly, currently much attention is being devoted to the development of effective methods and reagents for their synthesis. In contrast, considerably less effort has been afforded to the development of preparing C?SeCF3 bonds. Herein we report a concise route to synthesize a family of copper(I) trifluoromethylselenolate reagents by the reaction of CuI with the Ruppert’s reagent (Me3SiCF3), KF, and elemental selenium in the presence of dinitrogen ligands in CH3CN at room temperature. The reagent [Cu(bpy)(SeCF3)]2 was proven to be air‐stable and highly efficient for nucleophilic trifluoromethylthselenolation of a broad range of (hetero)aryl halides and alkyl halides. This method represents a powerful protocol for the construction trifluoromethylselenolate compounds. 相似文献
102.
Cellulosic nanocomposite membranes from hydroxypropyl cellulose reinforced by cellulose nanocrystals 总被引:1,自引:0,他引:1
Lin Ma Lili Wang Lixin Wu Dongxian Zhuo Zixiang Weng Rongrong Ren 《Cellulose (London, England)》2014,21(6):4443-4454
Cellulosic nanocomposite membranes were prepared by incorporation of cellulose nanocrystals (CNCs) into a hydroxypropyl cellulose (HPC) matrix using a mixing/evaporation technique. CNCs were obtained from filter paper using the sulfuric acid hydrolysis method with the aid of ultrasonication. The relationship between the microstructure and mechanical properties of the CNCs/HPC nanocomposite membranes was studied. Scanning electron microscopy showed that the CNCs were well dispersed in the HPC matrix, and the fracture surface demonstrated a fibrous characteristic. With increasing CNCs content, the tensile strength and Young’s modulus of the CNCs/HPC nanocomposite membranes gradually increased. At 5 wt% content of CNCs, the strength was increased by 525 % and the Young’s modulus by 124 % compared with pure HPC membrane. Moreover, the effect of the phase change of HPC on the mechanical properties of the CNCs5wt%/HPC nanocomposite membranes and the corresponding mechanism were also studied. 相似文献
103.
X‐Ray Emission Spectroscopy: A Spectroscopic Measure for the Determination of NO Oxidation States in Fe–NO Complexes 下载免费PDF全文
Prof. Tsai‐Te Lu Dr. Tsu‐Chien Weng Prof. Wen‐Feng Liaw 《Angewandte Chemie (International ed. in English)》2014,53(43):11562-11566
Extensive study of the electronic structure of Fe‐NO complexes using a variety of spectroscopic methods was attempted to understand how iron controls the binding and release of nitric oxide. The comparable energy levels of NO π* orbitals and Fe 3d orbitals complicate the bonding interaction within Fe? NO complexes and puzzle the quantitative assignment of NO oxidation state. Enemark–Feltham notation, {Fe(NO)x}n, was devised to circumvent this puzzle. This 40‐year puzzle is revisited using valence‐to‐core X‐ray emission spectroscopy (V2C XES) in combination with computational study. DFT calculation establishes a linear relationship between ΔEσ2s*‐σ2p of NO and its oxidation state. V2C Fe XES study of Fe? NO complexes reveals the ΔEσ2s*‐σ2p of NO derived from NO σ2s*/σ2p→Fe1s transitions and determines NO oxidation state in Fe? NO complexes. Quantitative assignment of NO oxidation state will correlate the feasible redox process of nitric oxide and Fe‐nitrosylation biology. 相似文献
104.
Hua Chyn Lee Kah Weng Siew Maksudur R.Khan Sim Yee Chin Jolius Gimbun Chin Kui Cheng 《天然气化学杂志》2014,(5):645-656
The paper reports the development of cement clinker-supported nickel (with metal loadings of 5 wt%, 10 wt%, 15 wt% and 20 wt%) catalysts for glycerol dry (CO2) reforming reaction. XRF results showed that CaO constituted 62.0% of cement clinker. The physicochemical characterization of the catalysts revealed 32-folds increment of BET surface area (SBET) with the addition of nickel metal into the cement clinker, which was also corroborated by FESEM images. Significantly, XRD results suggested different types of Ni oxides formation with Ni loading, whilst Ca3SiO5 and Ca2Al0.67Mn0.33FeO5 were the main crystallite species for pure cement clinker. Temperature-programmed reduction analysis yielded three domains of H2 reduction peaks, viz. centered at approximately 750 K referred to as type-Ⅰ peaks, another peaks at 820 K denoted as type-Ⅱ peaks and the highest reduction peaks, type-Ⅲ recorded at above 1000 K. 20 wt% Ni was found to be the best loading with the highest XG and H2 yield, whilst the lowest methanation activity. Syngas with lower H2/CO ratios (0.6 to 1.5) were readily produced from glycerol dry reforming at CO2-to-Glycerol feed ratio (CGR) of unity. Nonetheless, carbon deposit comprised of whisker type (Cv) and graphitic-like type (Cc) species were found to be in majority on 20 wt%Ni/CC catalysts. 相似文献
105.
利用溶胶-凝胶法,采用三种酸性金属氧化物(氧化铌、氧化钨和氧化钼)对锰铈复合氧化物催化剂进行了改性. 测试了催化剂的氮氧化物选择性催化还原(SCR)活性,以筛选对应不同温度窗口的合适酸性氧化物改性剂. 同时评价了催化剂的NO氧化和NH3氧化活性. 利用X射线衍射、BET比表面积测试、H2程序升温还原、NH3/NOx程序升温脱附和NH3/NOx吸附红外光谱等手段对催化剂进行了表征. MnOx-CeO2催化剂表现出良好的低温(100-150 ℃)活性. 酸性金属氧化物的添加削弱了催化剂的氧化还原特性,从而抑制了NH3的活化和NO2辅助的快速SCR反应. 与此同时,相对高温(250-350 ℃)区NH3的氧化也受到了抑制,B酸和L酸上的NH3吸附得以增强. 因此,催化剂的SCR脱硝温度窗口向高温移动,改性效果Nb2O5 < WO3 < MoO3. 相似文献
106.
Fengjun Liu Zihan Wu Boshang Hou Zhiqiang Dong Yuhua Weng Rui Pan Zhenling Xu Chunyan Zhang Yinyun Lü Xiaoqing Ouyang Chanzi Ruan 《大学化学》2020,35(9):83-88
By using light sensors of the cellphone, we build a simple photometer which can be used in quantitative analysis experiments. We have performed 5 replicate measurements of iron with phenanthroline to verify reproducibility and stability. We find the absorbance of the sample has a good linear relationship with the concentrations of iron with a R2 value around 0.999 and the RSD of 2.81%. The result is 4.94 μg·mL-1 with spectrophotometer and 5.11 μg·mL-1 with our photometer. The photometer is simple, convenient, accurate and realistic by using a phone as detector, which can replace the traditional spectrophotometer in the laboratory class. The students can enhance their understanding of the structure and principle of spectrophotometer by the DIY photometer experiment. 相似文献
107.
Visible light-induced hydroxyalkylation of 2H-benzothiazoles with alcohols via selectfluor oxidation
A visible-light induced metal-free approach was described for the hydroxyalkylation of 2H-benzothiazoles with alcohols by using selectfluor as the oxidant. A variety of 2H-benzothiazoles and alcohols could be tolerated, providing a mild and simple method for the synthesis of C2-hydroxyalkylated 2H-benzothiazoles in moderate to good yields. Besides, ethers were also compatible in this reaction, leading to corresponding C2 ether-substituted 2H-benzothiazoles with high regioselectivity. 相似文献
108.
Xiaoting Li Tao Hu Biao Wang Wenjian Weng Gaorong Han Chenglu Song Ning Ma Piyi Du 《Journal of Physics and Chemistry of Solids》2013
(100) Oriented (PbxSr1−x)TiO3 (PST) thin films were prepared on indium tin oxide coated glass substrates by sol–gel technique with rapid thermal processing. The dielectric permittivity and tunability of the thin films with different dispersion degrees of orientation were investigated in detail by characterizing the full width at half maximum of their (100) peak based on rocking curves at different annealing temperatures. Influence of orientation dispersion on dielectric properties was exhibited in the tunable dielectric thin films. It shows that the dielectric constant and hence the tunability of the sol–gel derived PST thin films are improved with the decrease in the dispersion degree of orientation of the perovskite phase other than the increase in the content of crystalline phase in the thin films. The dielectric constant (capacitance) and figure of merit of the oriented thin films are 3–6 times and 1 times higher than that of randomly oriented thin film respectively. 相似文献
109.
110.