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991.
Structure and Reaction Chemistry of Magnesium Organocuprates Derived from Magnesiacyclopentadienes and Copper(I) Salts 下载免费PDF全文
Liang Liu Dr. Junnian Wei Yue Chi Prof. Dr. Wen‐Xiong Zhang Prof. Dr. Zhenfeng Xi 《Angewandte Chemie (International ed. in English)》2016,55(47):14762-14765
The chemistry of magnesium organocuprates, including their synthesis, structures, and reactions, remains underexplored. In this work, by taking advantage of the high reactivity and ready availability of magnesiacyclopentadienes, a series of magnesiacyclopentadiene‐based organocuprates were synthesized and structurally characterized. A variety of CuX salts (X=Cl, Br, I, or alkynyl) were successfully applied to react with magnesiacyclopentadienes. Besides CuX salts, AgX salts (X=Cl, alkynyl) also undergwent the above reaction to afford the corresponding magnesium organoargentates. Single‐crystal X‐ray structural analysis and DFT calculations of these butadienyl magnesium organocuprates revealed unique structural characteristics and bonding modes. These results are also very useful to understand the transmetalation process, since the product can be viewed as the resting‐state intermediate of a transmetalation reaction between organomagnesium compounds and coinage‐metal salts. Preliminary information on the reaction chemistry of these magnesium organocuprates is provided by their reactions with allyl bromide, benzoyl chloride, and CO2. 相似文献
992.
用电压传感器测得使用铝、镁作电极,氢氧化钠溶液或氨水作电解质的原电池,在放电过程中存在电极极性翻转现象,说明铝片不仅能与强碱反应,也能与氨水反应。该结论和铝片和氨水反应的试管实验的结果一致。换用碳酸钠溶液作电解质的原电池不存在电极极性翻转现象;结合试管实验中铝片与碳酸钠溶液反应的产物分析,发现有难溶于水的碱式碳酸钠铝生成,推测其覆盖在铝片表面,避免了电极极性翻转。 相似文献
993.
正丁烷在VMgO和Ni-VMgO催化剂上氧化脱氢 总被引:3,自引:0,他引:3
采用4种方法制备了VMgO催化剂样品(w(V2O5)=30%,w(MgO)=70%),并将其用于正丁烷氧化脱氢气固相反应. 结果表明,MgO经蒸馏水回流和焙烧处理后再用NH4VO3溶液浸渍所制得的VMgO,对正丁烷氧化脱氢生成丁烯和丁二烯反应具有更好的催化性能. 这是由于用该法制备的VMgO催化剂中存在较多的Mg3V2O8物种. 通过添加Ni对VMgO催化剂进行了改性. 结果表明,适量添加Ni(n(Ni)/n(V)=0.3)有利于催化剂中Mg3V2O8的生成,而Ni以Ni3V2O8的形态存在. 由此明显改善了VMgO催化剂对正丁烷氧化脱氢生成丁烯和丁二烯反应的催化性能. 相似文献
994.
Bimetallic NiCo Functional Graphene: An Efficient Catalyst for Hydrogen‐Storage Properties of MgH2 下载免费PDF全文
Ying Wang Guang Liu Cuihua An Li Li Fangyuan Qiu Prof. Yijing Wang Lifang Jiao Prof. Huatang Yuan 《化学:亚洲杂志》2014,9(9):2576-2583
Bimetallic NiCo functional graphene (NiCo/rGO) was synthesized by a facile one‐pot method. During the coreduction process, the as‐synthesized ultrafine NiCo nanoparticles (NPs), with a typical size of 4–6 nm, were uniformly anchored onto the surface of reduced graphene oxide (rGO). The NiCo bimetal‐supported graphene was found to be more efficient than their single metals. Synergetic catalysis of NiCo NPs and rGO was confirmed, which can significantly improve the hydrogen‐storage properties of MgH2. The apparent activation energy (Ea) of the MgH2? NiCo/rGO sample decreases to 105 kJ mol?1, which is 40.7 % lower than that of pure MgH2. More importantly, the as‐prepared MgH2? NiCo/rGO sample can absorb 5.5 and 6.1 wt % hydrogen within 100 and 350 s, respectively, at 300 °C under 0.9 MPa H2 pressure. Further cyclic kinetics investigation indicates that MgH2? NiCo/rGO nanocomposites have excellent cycle stability. 相似文献
995.
In-Chyuan Ho Yuhuan Xu John D. Mackenzie 《Journal of Sol-Gel Science and Technology》1997,9(3):295-301
MgO thin films with either (111) or (200) preferential orientation have been prepared on (100) Si substrates by sol-gel method after a heat-treatment at 800°C. The obtained (111) preferentially oriented MgO film has a dielectric constant of 7.0 with a loss factor of 5% and a dielectric strength higher than 8 × 105 V/cm. The optical refractive index, which depends on the film thickness, is 1.71 when the film thickness is 260 nm. The surface structure of the Si substrate is believed to affect the preferential orientation of the sol-gel derived MgO film. Specifically, the microstructures at the interface indicate an interdiffusion of Mg, O, and Si between the film and the substrate. 相似文献
996.
制备了铌镁酸铅-钛酸铅(PMN-PT)铁电薄膜,并通过紫外-可见(UV-Vis)透射光谱、X射线衍射(XRD)和原子力显微镜(AFM)对其进行了表征.为了研究体异质结型有机共混膜的光电流特性,制作了氧化铟锡(ITO)/PMN-PT/有机共混膜/铝(Al)的光伏器件,调制激光照射下外加偏压的极性和大小变化将直接改变瞬态光电流的极性和大小,从而可在实验上证明传统体异质结型有机光伏器件的光电流极性是由器件阴、阳电极的功函数差所导致的内建电场的方向决定.同时也提出了一种利用铁电薄膜来研究体异质结型有机光伏器件光电流特性的新方法. 相似文献
997.
998.
A full functionalization of all four positions of the thieno[3,2‐b]thiophene scaffold was achieved. Starting from 2,5‐dichlorothieno[3,2‐b]thiophene, magnesiation of the 3‐ and 6‐position using tmpMgCl?LiCl furnishes, after trapping with various electrophiles, 3,6‐difunctionalized dichlorothieno[3,2‐b]thiophenes. Subsequent dechlorination and regioselective metalation or regioselective magnesium insertion into the C? Cl bond provides fully functionalized thieno[3,2‐b]thiophenes. Furthermore, new condensed heterocycles and small oligomers of these compounds with potential applications in material chemistry have been prepared. 相似文献
999.
Water, magnesium acetate,
magnesium chloride, acetic acid and hydrochloric acid were used as hydrating
agents for an industrially obtained MgO sample. The influence of these different
hydrating agents on the pH of the hydrating solution, degree of hydration
to Mg(OH)2, and product surface area was studied as
a function of the temperature of hydration. When compared to the hydration
in water, all hydrating agents improved the degree of hydration between 5
and 50% at all temperatures. MgCl2 and a mixture of
HCl and Mg(CH3COO)2 seemed to
be the most effective hydrating agents below 60°C, while at temperatures
above 60°C Mg(CH3COO)2 formed
the largest percentage Mg(OH)2. Mg(CH3COO)2
was the hydrating agent that showed the strongest temperature dependence.
The mechanism of the hydration reaction seems to be dependent of the availability
of Mg2+ ions and the increased formation of Mg(OH)2
as temperature increases. 相似文献
1000.
Jorma Hölsä Marco Kirm Mika Lastusaari Janne Niittykoski Pavel Novák 《Journal of luminescence》2009,129(12):1560-1563
The electronic structures of the distrontium magnesium disilicate (Sr2MgSi2O7(:Eu2+)) materials were studied by a combined experimental and theoretical approach. The UV-VUV synchrotron radiation was applied in the experimental study while the electronic structures were investigated theoretically by using the density functional theory. The structure of the valence and conduction bands and the band gap energy of the material as well as the position of the Eu2+ 4f ground state were calculated. The calculated band gap energy (6.7 eV) agrees well with the experimental value of 7.1 eV. The valence band consists mainly of the oxygen states and the bottom of the conduction band of the Sr states. The calculated occupied 4f ground state of Eu2+ lies in the energy gap of the host though the position depends strongly on the Coulomb repulsion strength. The position of the 4f ground state with respect to the valence and conduction bands is discussed using the theoretical and experimental evidence available. 相似文献