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981.
Metal‐Free Aminosulfonylation of Aryldiazonium Tetrafluoroborates with DABCO⋅(SO2)2 and Hydrazines
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Danqing Zheng Yuanyuan An Dr. Zhenhua Li Prof. Dr. Jie Wu 《Angewandte Chemie (International ed. in English)》2014,53(9):2451-2454
The coupling of aryldiazonium tetrafluoroborates, DABCO?(SO2)2, and hydrazines under metal‐free conditions leads to the formation of aryl N‐aminosulfonamides. The reaction proceeds smoothly at room temperature and shows broad functional‐group tolerance. A radical process is proposed for this transformation. 相似文献
982.
A Doping Technique that Suppresses Undesirable H2 Evolution Derived from Overall Water Splitting in the Highly Selective Photocatalytic Conversion of CO2 in and by Water
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Prof. Dr. Kentaro Teramura Zheng Wang Dr. Saburo Hosokawa Prof. Dr. Yoshihisa Sakata Prof. Dr. Tsunehiro Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9906-9909
Photocatalytic conversion of CO2 to reduction products, such as CO, HCOOH, HCHO, CH3OH, and CH4, is one of the most attractive propositions for producing green energy by artificial photosynthesis. Herein, we found that Ga2O3 photocatalysts exhibit high conversion of CO2. Doping of Zn species into Ga2O3 suppresses the H2 evolution derived from overall water splitting and, consequently, Zn‐doped, Ag‐modified Ga2O3 exhibits higher selectivity toward CO evolution than bare, Ag‐modified Ga2O3. We observed stoichiometric amounts of evolved O2 together with CO. Mass spectrometry clarified that the carbon source of the evolved CO is not the residual carbon species on the photocatalyst surface, but the CO2 introduced in the gas phase. Doping of the photocatalyst with Zn is expected to ease the adsorption of CO2 on the catalyst surface. 相似文献
983.
Frontispiece: New Insight into the Hydrocarbon‐Pool Chemistry of the Methanol‐to‐Olefins Conversion over Zeolite H‐ZSM‐5 from GC‐MS,Solid‐State NMR Spectroscopy,and DFT Calculations
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984.
Chemical and Toxicological Investigations of a Previously Unknown Poisonous European Mushroom Tricholoma terreum
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Xia Yin Dr. Tao Feng Prof. Jian‐Hua Shang Yun‐Li Zhao Fang Wang Zheng‐Hui Li Ze‐Jun Dong Prof. Dr. Xiao‐Dong Luo Prof. Dr. Ji‐Kai Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7001-7009
The established tradition of consuming and marketing wild mushrooms has focused attention on mycotoxicity, which has become a global issue. In the present study, we describe the toxins found in a previously unknown poisonous European mushroom Tricholoma terreum. Fifteen new triterpenoids terreolides A–F ( 1 – 6 ) and saponaceolides H–P ( 8 – 16 ) were isolated from the fruiting bodies of the toxic mushroom T. terreum. Terreolides A–C ( 1 – 3 ) possessed a unique 5/6/7 trioxaspiroketal system, whereas terreolides D–F ( 4 – 6 ) possessed an unprecedented carbon skeleton. Two abundant compounds in the mushroom, saponaceolide B ( 7 ) and saponaceolide M ( 13 ), displayed acute toxicity, with LD50 values of 88.3 and 63.7 mg kg?1 when administered orally in mice. Both compounds were found to increase serum creatine kinase levels in mice, indicating that T. terreum may be the cause of mushroom poisoning ultimately leading to rhabdomyolysis. 相似文献
985.
AgI Microplate Monocrystals with Polar {0001} Facets: Spontaneous Photocarrier Separation and Enhanced Photocatalytic Activity
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Dr. Qin Kuang Xiaoli Zheng Prof. Shihe Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2637-2645
Elucidating the facet‐dependent photocatalytic activity of semiconductor photocatalysts is important in improving the overall efficiency of photocatalysis. Furthermore, combining facet control with selective deposition of oxidation and/or reduction cocatalysts on specific faces of semiconductor photocatalysts is potentially an effective strategy to synergistically optimize the functionality of photocatalysts. In the present study, high‐purity wurtzite‐type β‐AgI platelet microcrystals with polar {0001} facets were prepared by a facile polyvinylpyrrolidone‐assisted precipitation reaction. The polar‐faceted AgI microplates were used as archetypes to demonstrate preferential diametric migration (i.e., effective separation) of photogenerated electrons and holes along the c axis. Such vectorial electron–hole separation stems from the asymmetric surface structures, which give rise to distinct photoexcited reaction behaviors on the ±(0001) polar facets of wurtzite‐type semiconductors. Furthermore, on selective deposition of Ag and MnOx (1.5<x<2) cocatalysts on the reductive (0001) and oxidative (000$\bar 1$ ) facets, respectively, photocatalytic activity of the AgI microplates in degrading organic pollutants was dramatically enhanced thanks to the broad light‐absorption range, strong dye‐adsorption ability, and effective spatial separation of photocarriers. 相似文献
986.
987.
In order to broaden applications of viscose fiber, graft copolymerization of acrylic acid was conducted on its surface followed by in situ loading of Ag nanoparticles (Ag-NPs). The loading amount of Ag-NPs was affected by the concentrations of Ag+ and trisodium citrate, and their optimum concentrations were found to be 0.014 and 0.030 g/ml. The Ag-NP-loaded fibers presented a prolonged Ag release behavior in aqueous solution, of which the cumulative release was less than 5 % within 48 h. In addition, the viscose fibers showed good antimicrobial activity against S. aureus, and their consecutive antimicrobial activity was kept at more than 90 % after several washing cycles. Modified viscose fibers, therefore, offer a great opportunity for use as antimicrobial fabrics. 相似文献
988.
采用PVT膨胀仪测试了添加不同防老剂的天然橡胶(NR)复合材料的压力-体积-温度(P-V-T)属性,通过最小二乘法拟合得到Tait方程参数,预测了体系的热膨胀系数(α)和等温压缩系数(β),结果表明,Tait状态方程可用来预测该复合材料体系的P-V-T行为,NR复合材料的α值随着压力的增大而减小,随温度变化不明显;β值随压力的增大而减小,且随着温度的升高而升高.分子模拟结果观察了体系凝聚态结构在不同温度下的变化,表明其变化原因是升温使体系自由体积增大,分子链的活动性增强,同时观察到单独加入防老剂4010NA或防老剂RD的体系α和β的值较大,说明其尺寸稳定性差,而当同时加入4010NA和RD进行防老剂并用时,体系的α和β值均较小,表明此复合材料体系不容易产生变形;通过分子动力学模拟手段计算了NR复合材料的内聚能密度(CED)随温度的变化规律,对于2种防老剂并用的体系,其CED比较大,说明分子间相互作用力较强,从而体系尺寸稳定性好,受温度和压力的影响小. 相似文献
989.
Palladium‐Catalyzed Decarboxylative Cycloaddition of Vinylethylene Carbonates with Formaldehyde: Enantioselective Construction of Tertiary Vinylglycols
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Ajmal Khan Dr. Renfeng Zheng Prof. Dr. Yuhe Kan Jiang Ye Juxiang Xing Prof. Dr. Yong Jian Zhang 《Angewandte Chemie (International ed. in English)》2014,53(25):6439-6442
An efficient method for the enantioselective construction of tertiary vinylglycols through a palladium‐catalyzed asymmetric decarboxylative cycloaddition of vinylethylene carbonates with formaldehyde was developed. By using a palladium complex generated in situ from [Pd2(dba)3]?CHCl3 and a phosphoramidite ligand as a catalyst under mild reaction conditions, the process allows conversion of racemic 4‐substituted 4‐vinyl‐1,3‐dioxolan‐2‐ones into the corresponding 1,3‐dioxolanes, as methylene acetal protected tertiary vinylglycols, in high yields with good to excellent enantioselectivities. 相似文献
990.
Exceedingly Fast Copper(II)‐Promoted ortho CH Trifluoromethylation of Arenes using TMSCF3
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Ming Shang Shang‐Zheng Sun Dr. Hong‐Li Wang Dr. Brian N. Laforteza Prof. Dr. Hui‐Xiong Dai Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2014,53(39):10439-10442
The direct ortho‐trifluoromethylation of arenes, including heteroarenes, with TMSCF3 has been accomplished by a copper(II)‐promoted C? H activation reaction which completes within 30 minutes. Mechanistic investigations are consistent with the involvement of C? H activation, rather than a simple electrophilic aromatic substitution (SEAr), as the key step. 相似文献