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排序方式: 共有2819条查询结果,搜索用时 15 毫秒
1.
Haixing Guan Qianwen Zhang Prof. Dr. Patrick J. Walsh Prof. Dr. Jianyou Mao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(13):5210-5215
A unique nickel/organic photoredox co-catalyzed asymmetric reductive cross-coupling between α-chloro esters and aryl iodides is developed. This cross-electrophile coupling reaction employs an organic reductant (Hantzsch ester), whereas most reductive cross-coupling reactions use stoichiometric metals. A diverse array of valuable α-aryl esters is formed under these conditions with high enantioselectivities (up to 94 %) and good yields (up to 88 %). α-Aryl esters represent an important family of nonsteroidal anti-inflammatory drugs. This novel synergistic strategy expands the scope of Ni-catalyzed reductive asymmetric cross-coupling reactions. 相似文献
2.
Alexander Y. Galashev Konstantin P. Katin Mikhail M. Maslov 《Physics letters. A》2019,383(2-3):252-258
We present Morse parameters for the interaction of graphene and silicene surfaces with the atoms of practically important metals Ni, Ag, and Li. The parameters' values are derived from the dispersion corrected density functional calculations. Two possible cases of -hybridized C/Si atoms in the unbroken graphene/silicene sheets and sp-hybridized atoms near the vacancies are considered. Proposed Morse parameters' sets reproduce binding energies, bond lengths and oscillation frequencies of metal atoms adsorbed on the hollow positions over the rings of C60 and Si60 fullerenes. They also reproduce well the same quantities for the substituted C59M and Si59M fullerenes (M?=?Ni, Ag, Li). 相似文献
3.
Liang‐An Chen Alan R. Lear Pin Gao M. Kevin Brown 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11072-11076
A method for the construction of boron‐substituted quaternary carbons or diarylquaternary carbons by arylboration of highly substituted alkenylarenes is presented. A wide range of alkenes and arylbromides can participate in this reaction thus allowing for a diverse assortment of products to be prepared. In addition, a solvent dependent regiodivergent arylboration of 1,2‐disubstituted alkenylarenes is presented, thus greatly increasing the scope of products that can be accessed. 相似文献
4.
5.
Adiran deAguirre Ignacio Funes‐Ardoiz Feliu Maseras 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3938-3942
The computational characterization of the full catalytic cycle for the synthesis of indoline from the reaction between iodoacetanilide and a terminal alkene catalyzed by a nickel complex and a photoactive ruthenium species is presented. A variety of oxidation states of nickel, Ni0, NiI, NiII, and NiIII, is shown to participate in the mechanism. Ni0 is necessary for the oxidative addition of the C?I bond, which goes through a NiI intermediate and results in a NiII species. The NiII species inserts into the alkene, but does not undergo the reductive elimination necessary for C?N bond formation. This oxidatively induced reductive elimination can be accomplished only after oxidation to NiIII by the photoactive ruthenium species. All the reaction steps are computationally characterized, and the barriers for the single‐electron transfer steps calculated using a modified version of the Marcus Theory. 相似文献
6.
《Arabian Journal of Chemistry》2020,13(4):5191-5197
Nickel sulphide-reduced graphene oxide (NiS-rGO) composite films have been prepared via modified Hummers’s method assisted with spin coating technique. The NiS-rGO samples were then employed as counter electrode in a dye-sensitized solar cell (DSSC). The main aim of this work is to investigate the relationship between the concentrations of NiCl2 with the properties of NiS-rGO and performance parameters of the device. The dominant rGO and minor NiS phase exist in the composite. The morphology of the composite is white strips rGO and NiS agglomerate particle. The element of C, O, Ni and S present in the composite. The highest η of 1.04% and Jsc of 7.39 mA cm−2 were obtained from the device with 0.06 M NiCl2 resulted from the longest carrier lifetime. The photovoltaic parameters results reveal that NiS-rGO composite has potential to become as a free platinum counter electrode of DSSC. 相似文献
7.
Peng Yang Yaxin Sun Kaiyue Fu Li Zhang Guang Yang Jieyu Yue Yu Ma Jianrong Steve Zhou Bo Tang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202111778
We report a stereoselective conversion of terminal alkynes to α-chiral carboxylic acids using a nickel-catalyzed domino hydrocarboxylation-transfer hydrogenation reaction. A simple nickel/BenzP* catalyst displayed high activity in both steps of regioselective hydrocarboxylation of alkynes and subsequent asymmetric transfer hydrogenation. The reaction was successfully applied in enantioselective preparation of three nonsteroidal anti-inflammatory profens (>90 % ees) and the chiral fragment of AZD2716. 相似文献
8.
《Comptes Rendus Chimie》2015,18(3):293-301
Dry reforming of methane has been carried out on SBA-15 catalysts containing 5 wt% Ni and 6 wt% Ce. The effect of the order of Ni and Ce impregnation on the catalytic activity has been studied. Both metals were added using the “two-solvent” method that favors metal dispersion inside the pores. Characterizations by XRD (low and high angles), N2 sorption, SEM and TEM of the materials after metal addition and calcination indicate good preservation of the porosities and high NiO and CeO2 dispersion inside the porous channels. Reduction was carried out before the catalytic tests and followed by TPR measurements. The most active reduced catalyst was the Ni–Ce/SBA-15 sample prepared by impregnating cerium first, then nickel. All catalysts were highly active and selective towards H2 and CO at atmospheric pressure. Full CH4 conversion was obtained below 650 °C. The higher performances compared to those reported in the literature for mesoporous silica with supported Ni and Ce catalysts are discussed. 相似文献
9.
CMSX-4 is the second-generation nickel-based single crystal superalloy used widely in the world. The oxidation resistance and corrosion resistance of CMSX-4 alloy can be improved by adding trace lanthanum (La), cerium (Ce) and other rare earth elements. A method for the simultaneous determination of La and Ce in CMSX-4 nickel-based superalloy by wet dissolution-inductively coupled plasma mass spectrometry was established. The sample was heated and dissolved under normal pressure by aqua regia and hydrofluoric acid, and the interference of fluorine ion was eliminated by using perchloric acid. The amount of dissolved acid and the digestion conditions were optimized. The limits of detection were 0.23 μg/g for La and 0.85 μg/g for Ce under optimized conditions. The spiked recoveries were 95.0%–98.9% with the relative standard deviations of 1.3%–3.9%, which can meet the requirements of accurate and rapid determination of La and Ce in CMSX-4 nickel-based superalloy. © 2023, Youke Publishing Co.,Ltd. All rights reserved. 相似文献
10.
Jiehao Du Banggui Cheng Huiqing Yuan Yuan Tao Ya Chen Mei Ming Zhiji Han Richard Eisenberg 《Angewandte Chemie (International ed. in English)》2023,62(9):e202211804
We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes ( 1 – 5 ) in reducing CO2 to C1–3 hydrocarbons on carbon paper in pH-neutral aqueous solutions. Ni(mpo)2 ( 3 , mpo=2-mercaptopyridyl-N-oxide), Ni(pyS)3− ( 4 , pyS=2-mercaptopyridine), and Ni(mp)2− ( 5 , mp=2-mercaptophenolate) were found to generate C3 products from CO2 for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C1, C2, C3 hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FEC1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO2 reduction. 相似文献