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71.
Huatian Shi Jianhui Xie William W. Y. Lam Wai-Lun Man Chi-Keung Mak Shek-Man Yiu Hung Kay Lee Tai-Chu Lau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(56):12895-12899
The synthesis and X-ray structure of a new manganese(V) mesitylimido complex with a tetraamido macrocyclic ligand (TAML), [MnV(TAML)(N-Mes)]− ( 1 ), are reported. Compound 1 is oxidized by [(p-BrC6H4)3N ]+.[SbCl6]− and the resulting MnVI species readily undergoes H-atom transfer and nitrene transfer reactions. 相似文献
72.
Chaonan Xie Qin Li Gang Han Huan Liu Jien Yang Jincheng Li 《Biomedical chromatography : BMC》2019,33(5)
Tricaine methanesulfonate is one of most commonly used anesthetics in fish during blood sampling, artificial propagation and long‐distance transportation. In this study, an accurate method for the quantitative determination of tricaine in fish samples by a stable isotope dilution assay coupled with high‐performance liquid chromatography–triple quadrupole mass spectrometry was developed. Tricaine‐D5 was synthesized and used as an isotopically labeled internal standard for the determination of tricaine. The analytical performance of the method was validated for tricaine determination in marine fish and freshwater fish. The determination of tricaine was linear in the range of 2.0–200.0 μg L?1. The limit of detection and limit of quantitation for fish muscle tissues were 1.0 and 4.0 μg kg?1, respectively. Good recoveries were obtained in the range of 92.08–97.50%. The inter‐ and intra‐assay relative standard deviations (RSD values) were investigated, and the values were 0.39–3.01 and 0.85–2.77%, respectively. The values of CCα and CCβ were 10.21–10.43 and 10.42–10.87 μg kg?1, respectively. The clearance of MS‐222 from grass carp was further studied using our method. The results demonstrate that MS‐222 could be well absorbed and rapidly eliminated after bath administration. 相似文献
73.
Peng Jiehui Zhan Pei Deng Runkang Zhang Yanli Xie Xinyuan 《Research on Chemical Intermediates》2019,45(9):4637-4651
Research on Chemical Intermediates - In this paper, a one-pot and sustainable method for the preparation of Ag/ZnO nanocomposites in green polyethylene glycol-200 (PEG-200) was reported with silver... 相似文献
74.
Xiaoming Ma Xiaofeng Zhang Guoshu Xie John Mark Awad Wei Zhang 《Tetrahedron letters》2019,60(40):151127
The one-pot synthesis of tetrahydro-epiminobenzo[b]azocines through a sequential 1,3-dipolar cycloaddition and intramolecular Staudinger-aza-Wittig reaction sequence is reported. This methodology provides a new and efficient approach for medium-sized and bridged nitrogen heterocyclic molecules. 相似文献
75.
In this paper, we show that the peeling property still holds for Bondi-Sachs metrics with nonzero cosmological constants under the boundary condition given by Sommerfeld's radiation condition together with three nontrivial Λ-independent functions B, a and b. This should indicate that the new boundary condition is natural. Moreover, we construct some nonstationary vacuum Bondi-Sachs metrics without Bondi news, whose Newman-Penrose quantities fall faster than usual. This provides a new feature of gravitational waves for nonzero cosmological constants. 相似文献
76.
Qiong-Tao Xie 《理论物理通讯》2020,72(6):65105-64
An analytical method is developed to study the two-mode quantum Rabi model. For certain specific parameter conditions, especially for the resonant conditions, we obtain an infinite number of the exact solutions of the eigenfunctions and associated energies. It is shown that there exist new types of the exact energies which do not correspond to the level-crossings. Our analytical method may find applications in some related models. 相似文献
77.
Xiao Jun-An Cheng Xiu-Liang Peng Hai Li Jin-Lian Xie Zhen-Zhen Chen Wen-Qiang Liu Zhi-Ping Xiao Qi Su Wei Yang Hua 《中国科学:化学(英文版)》2020,63(6):785-791
A diastereoselectivity-controllable formal [3+2]-cycloaddition of arylvinyl oxirane 2,2-diesters with cyclic N-sulfonyl imines is developed, affording the corresponding tricyclic oxazolidine derivatives in moderate to excellent yields with excellent diastereoselectivities in the presence of palladium(0) or scandium(III) triflate. This protocol allows selective synthesis of diastereomers of tricyclic oxazolidine derivatives under switchable and mild conditions. Further transformations of the obtained products were conducted by removing ester groups and arylvinyl moieties. 相似文献
78.
工业催化:选择性提升策略 总被引:1,自引:0,他引:1
工业催化直接或间接贡献了世界GDP的20%-30%,推动了产业变革和社会进步.对于工业催化,开发高活性、高选择性和高稳定性的多相催化剂至关重要,而选择性是最主要的挑战.因为实现催化选择性的精确控制是绿色化学的重要概念之一,更是工业催化可持续发展的重要驱动力;而且,选择性不仅决定了催化过程的原子经济性,也影响到后续分离过程的能耗.针对多数工业催化反应存在'活性越高、选择性越低'的相互制约与矛盾问题,本文以若干能源化工催化反应为例,试图总结催化选择性提升的一般策略,以期为有关工业应用的催化新过程提供科学参考.多相催化一般经历与反应物有关的步骤(反应物的外扩散、内扩散和化学吸附)、与反应有关的步骤(活化和表面反应)、以及与产物相关的步骤(产物脱附、内扩散和外扩散).本文依此归纳并举例说明提高选择性的一般策略.在汽油催化吸附脱硫中,主要利用了催化剂中零价镍-氧化锌耦合活性中心的选择吸附策略,使零价镍优先吸附含硫化合物,从而实现选择性脱硫而不饱和烯烃.在甲苯和甲醇侧链烷基化反应中,主要利用了特定空间分布的酸碱吸附位,实现吸附甲苯和稳定甲醛中间体的协同匹配.在乙苯脱乙基型二甲苯异构化反应中,主要利用了双床层对催化剂功能的分离策略,在不同的择形催化剂床层中分别进行乙苯脱乙基反应和二甲苯异构化反应,从而提高对二甲苯的产量.在苯选择加氢制环己烯反应中,主要利用强化产品脱附的策略,促进环己烯产品从亲水改性的催化剂表面脱附,实现环己烯选择性的提升.这些炼油与化工研究案例中同时存在多个连串-平行反应,主要是利用吸附中心、反应中心在时间或空间上的耦合、解耦或限域策略,调控不同途径的扩散能垒、反应能垒,实现了催化剂选择性的提升.多相催化多是复杂过程,基于提高选择性的初步认识,还要结合具体复杂催化过程,系统研究单策略以及多策略组合作用下的选择催化过程,实现在合理时间尺度、空间尺度上设计高选择性的催化剂,而这本质上是一种介尺度催化. 相似文献
79.
Dong-Liang Zhang Cheng-Long Deng Bin Xie Yu-Long Li Chuan Lai Wen-Yu Mou Lin-Xin He Xiao-Xue Bai Tao Li Jia-Xi Cao Jun Wang 《应用有机金属化学》2020,34(1):e5261
Six new O-alkyldithiophosphate nickel complexes with dcpf ligand, [(dcpf)Ni(S2P{O}OR)] (dcpf = 1,1′-bis (dicyclohexylphosphino)ferrocene, R = CH3 ( 1 ), CH3CH2 ( 2 ), Ph ( 3 ), 4-MeC6H4 ( 4 ), PhCH2 ( 5 ) and PhCH2CH2 ( 6 )), have been synthesized by the treatment of dcpf with ((RO)2PS2)2Ni in satisfactory yields. These complexes were characterized by elemental analysis, spectroscopy (FTIR, UV–vis, 1H, 13C, and 31P NMR), thermogravimetric analysis and single crystal X-ray diffraction. The nickel atom in 1 , 2 ·CH2Cl2, 3 ·CH2Cl2, 4 ·2CH2Cl2·THF, and 2( 5 )·hexane adopts a slightly distorted square-planar coordination environment finished by two phosphorus atoms of dcpf ligand and two sulfur atoms of O-alkyldithiophosphate ligand. Furthermore, the electrochemical properties for complexes 1 – 6 were also investigated by cyclic voltammetry. With the addition of 120 mM trifluoroacetic acid (TFA), the turnover frequency (TOF) values for 1 – 6 are estimated to be 1243.83, 1046.54, 1331.71, 2545.29, 1899.03, and 1191.37 s−1, with the overpotential (η) values of 0.62, 0.58, 0.71, 0.67, 0.60, and 0.56 V, respectively. The result of electrochemical studies indicates that all complexes can be used as efficient molecular eletrocatalysts for the reduction of protons to hydrogen in the presence of TFA in MeCN. 相似文献
80.
We describe an effective and novel method to prepare N-aryl imidazoles via the copper quinolate-catalyzed N-arylation of aryl halides and imidazoles. A wide range of products were obtained in moderate to excellent yields under the optimal reaction conditions. Applying standard conditions, the model reaction could be performed on a gram scale. This method also presents a new avenue to the “click” reaction of terminal alkynes, benzyl bromide, and sodium azide and to the construction of C–C bonds by homocoupling of phenylboronic acid or phenylacetylene derivatives with the aid of copper quinolate. 相似文献