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排序方式: 共有1493条查询结果,搜索用时 31 毫秒
91.
基于量子化学密度泛函理论和过渡态理论研究了含酮基团对煤焦异相还原NO的影响及其产物发生氧脱附的微观反应机理。计算结果表明,NO更易于吸附在含酮基团煤焦表面。椅形含酮基团强化了煤焦异相还原NO;锯齿形含酮煤焦表面与NO异相反应决速步能垒值(495.45 kJ/mol)大于锯齿形纯碳基煤焦表面与NO决速步能垒值(331.32 kJ/mol),基于锯齿形含酮煤焦模型中的氧浓度不在利于NO还原的范围内而不易于NO的还原。中间产物P1在无CO存在情况下,较纯碳基煤焦表面更易于发生氧脱附而产生表面缺陷;在CO存在条件下,含酮煤焦表面为氧脱附过程提供自由活性位点,降低了过程能垒消耗。 相似文献
92.
Intermolecular Stetter reaction of aromatic aldehydes with (E)-(2-nitrovinyl)cyclohexane catalyzed by thiazolium A has been developed. The reaction rate and efficiency are profoundly impacted by the presence of thiourea B. The reaction affords moderate to good yields of the Stetter product. Some factors influencing yield were discussed. 相似文献
93.
Suman L. Jain 《合成通讯》2013,43(10):1459-1462
The oxidation of a variety of benzylic and secondary alcohols was achieved in excellent yields using an NBS/NH4Cl system in aqueous acetonitrile (CH3CN‐H2O; 7/3 v/v) at 80°C under very mild conditions. 相似文献
94.
Poly(aryl ether ketone) composite membrane as a high‐performance lithium‐ion batteries separator
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Min Xie Mingying Yin Guangdi Nie Jun Wang Ce Wang Danming Chao Xincai Liu 《Journal of polymer science. Part A, Polymer chemistry》2016,54(17):2714-2721
We described the design and synthesis of a modified poly(aryl ether ketone) bearing phenolphthalein and allyl groups (P‐PAEK) via nucleophilic polycondensation. A new kind of composite separator, crosslinked P‐PAEK/polyvinylidene fluoride (c‐P‐PAEK/PVDF) membrane was successfully prepared using phase separation, phase inversion method, and UV crosslinking technique. As a separator of lithium‐ion battery, c‐P‐PAEK/PVDF membrane demonstrates high porosity and uniform distribution of pores with interconnected pathways. Low thermal shrinkage, distinct shut‐down effect, high liquid electrolyte uptake capacity, and exciting liquid electrolyte wettability of the prepared c‐P‐PAEK/PVDF membrane have been revealed through comprehensive study. Moreover, the c‐P‐PAEK/PVDF membrane was applied to assemble a conventional Li/LiFePO4 coin cell, which exhibited hopeful cell performance. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2714–2721 相似文献
95.
A practical heterogeneous palladium‐catalyzed carbonylative Suzuki coupling of aryl iodides with arylboronic acids under carbon monoxide gas‐free conditions has been developed using a bidentate phosphino‐functionalized magnetic nanoparticle‐immobilized palladium(II) complex as catalyst. Formic acid was utilized as the carbon monoxide source with dicyclohexylcarbodiimide as the activator, and a wide variety of biaryl ketones were generated in moderate to high yields. The new heterogeneous palladium catalyst can be prepared via a simple procedure and can easily be separated from a reaction mixture by simply applying an external magnet and recycled up to 10 times without any loss of activity. 相似文献
96.
A new monomer, (2,5‐dimethoxy)phenylhydroquinone (DMPH), was prepared in a two‐step synthetic procedure. One aromatic poly(ether ether ketone)s with 2,5‐dimethoxy phenyl side group (DMP‐PEEK) was synthesized via an aromatic nucleophilic substitution reaction with 4,4′‐difluorobenzophenone (DFB). Poly(ether ether ketone)s with 2,5‐dihydroxy phenyl side group (DHP‐PEEK) was obtained via hydrolysis of methoxy group on the DMP‐PEEK. Both of the high molecular weight polymers could be obtained despite the steric effect of the bulky pendant groups. The two polymers have good solubility at room temperature. 相似文献
97.
Katarzyna Sokolowska 《合成通讯》2014,44(20):2943-2954
This article describes efficient preparation of isomeric allyl phosphine oxides possessing a protected cyclohexanediol fragment. Their base-catalyzed interconversions are examined and reactions with the Grundmann ketone provide an adduct containing the rearranged vinyl phosphine oxide moiety, instead of 19-norvitamin D3 analogs, the expected products of the Horner–Wittig process. 相似文献
98.
The multicomponent condensation of an aryl aldehyde,acetyl chloride,acetonitrile,and enolizable ketone as one-pot synthesis of β-acetamido ketones in high yields was investigated using commercial,non-corrosive,and environmentally benign Keggin and Wells-Dawson heteropolyacid catalysts.The best catalyst was H5PW10V2O40.The methodology used simple experimental conditions,and the short reaction times and high yields indicate it is a useful strategy for the large scale synthesis of β-acetamido ketones. 相似文献
99.
Samuel O. Grim Anthony W. Yankowsky 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):191-195
Abstract The 31P chemical shifts of eleven (4-ZC6H4)3P compounds show a slight correlation with the Hammet [sgrave]para constant of Z. The unusually large upfield chemical shifts of (2-ZC6H4)3P compounds are attributed to an extreme “gamma” effect caused by the restricted conformations due to the steric influence of the ortho substituents. Chemical shifts are given for about thirty triarylphosphines, and group contributions to phosphine chemical shifts are listed for twenty-one aryl groups. 相似文献
100.
Boris I. Usachev Vyacheslav Ya. Sosnovskikh Mikhail A. Shafeev Gerd-Volker Röschenthaler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1315-1319
Abstract Alkyl 2-mercaptophenyl ketones react with trifluoroacetic anhydride in the presence of triethylamine to give 2-(trifluoromethyl)-4H-thiochromen-4-ones, which are transformed into the corresponding pyrazoles by treatment with hydrazine hydrate and into 1,1-dioxides by oxidation with H2O2 in AcOH. 相似文献