共查询到20条相似文献,搜索用时 15 毫秒
1.
Wei-xiaTu Bao-linHe Han-fanLiu Xue-lanLuo XunLiang 《高分子科学》2005,(2):211-217
Catalytic properties of polymer-stabilized colloidal metal nanoparticles synthesized by microwave irradiation were studied in the selective hydrogenation of unsaturated aldehydes, o-chloronitrobenzene and the hydrogenation of alkenes. The results show that nanosized metal particles synthesized by microwave irradiation have similar catalytic performance in selective hydrogenation of unsaturated aldehydes, better selectivity to o-chloroaniline in hydrogenation of o-chloronitrobenzene and higher catalytic activities in hydrogenation of alkenes, compared with metal clusters prepared by conventional heating. The same apparent activation energy (Ea = 29 kJ mol^-1) for hydrogenation of 1-heptene catalyzed with platinum nanoparticles prepared by both heating modes implied that the reaction followed the same mechanism. 相似文献
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《中国化学》2018,36(5):443-454
The asymmetric transfer and pressure hydrogenation of various unsaturated substrates provides a succinct pathway to important chiral intermediates and products such as chiral alcohols, amines, and alkanes. The use of earth‐abundant transition metals such as Fe, Co, Ni, and Cu in hydrogenation reactions provides an attractive alternative to traditionally used metals such as Ru, Rh, Ir, and Pd because they are comparatively inexpensive, less toxic, and as their name suggests, more abundant in nature. Earth‐abundant transition metal‐catalyzed asymmetric hydrogenation is rapidly becoming an important area of research. This review summarizes advances in the asymmetric hydrogenation of unsaturated bonds (ketones, imines, and alkenes) with earth‐abundant transition metals. 相似文献
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Zheng Niu Weijie Zhang Pui Ching Lan Briana Aguila Shengqian Ma 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(22):7498-7502
Frustrated Lewis pairs (FLPs) have recently been advanced as efficient metal‐free catalysts for catalytic hydrogenation, but their performance in chemoselective hydrogenation, particularly in heterogeneous systems, has not yet been achieved. Herein, we demonstrate that, via tailoring the pore environment within metal–organic frameworks (MOFs), FLPs not only can be stabilized but also can develop interesting performance in the chemoselective hydrogenation of α,β‐unsaturated organic compounds, which cannot be achieved with FLPs in a homogeneous system. Using hydrogen gas under moderate pressure, the FLP anchored within a MOF that features open metal sites and hydroxy groups on the pore walls can serve as a highly efficient heterogeneous catalyst to selectively reduce the imine bond in α,β‐unsaturated imine substrates to afford unsaturated amine compounds. 相似文献
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Priv.‐Doz. Dr. Jan Paradies 《Angewandte Chemie (International ed. in English)》2014,53(14):3552-3557
The metal‐free activation of hydrogen by frustrated Lewis pairs (FLPs) is a valuable method for the hydrogenation of polarized unsaturated molecules ranging from imines, enamines, and silyl enol ethers to heterocycles. However, one of the most important applications of hydrogenation technology is the conversion of unsaturated hydrocarbons into alkanes or alkenes. Despite the fast development of the FLP chemistry, such reactions proved as highly challenging. This Minireview provides an overview of the basic concepts of FLP chemistry, the challenge in the hydrogenation of unsaturated hydrocarbons, and first solutions to this central transformation. 相似文献
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A number of transition metal catalysts have been developed for transfer hydrogenation of organic molecules. This method provides a useful process for the reduction of unsaturated molecules without the need for explosive hydrogen gas. An important development in this area is the design of new ligands that improve activity and selectivity under mild reaction conditions. Polydentate ligands are good candidates for producing high performance metal catalysts. This digest describes recent developments in transfer hydrogenation as well as asymmetric reactions using metal catalysts containing polydentate ligand systems. 相似文献
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《Comptes Rendus Chimie》2014,17(7-8):790-800
Activity and selectivity of bimetallic catalysts for two model reactions, citral hydrogenation in isopropanol and nitrate reduction in water, are reviewed on the basis of results obtained over bimetallic systems prepared in our laboratory, notably by redox techniques. The parent metal is generally a noble metal (Rh, Pd, Pt), while the additive is most often a non-noble metal (Ge, Sn, Cu…) whose oxidation state plays an important role in hydrogenation. Dramatic improvements of the selectivity to unsaturated alcohols are observed in citral hydrogenation with adequate deposition of the additive and pretreatment of the final catalyst. In nitrate reduction, the second metal essentially affects the first step of the process (conversion of nitrate to nitrite) but the global selectivity (limitation of NH3 formation) may be significantly improved by tuning the couple parent metal–additive. Other aspects such as the choice of the support and the optimization of reaction conditions (temperature, pressure, pH effects in water) are also discussed. 相似文献
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In recent years, Hantzsch esters and their related organic hydride donors have been widely utilized in biomimetic approaches of asymmetric transfer hydrogenation (ATH) reactions. Various compounds containing C=C, C=N and C=O unsaturated functionalities could be reduced in the presence of organocatalysts or transition metal complexes, affording versatile chiral building blocks in high yields and excellent enantioselectivities under mild conditions. In this critical review, recent advances in this area are summarized and classified according to unsaturated functional groups being reduced and catalytic systems employed (91 references). 相似文献
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简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果.首先,我们以环己烯加氢为探针反应,证明了平行使用多种研究手段的重要性,包括单晶表面的基础研究与DFT计算,多晶表面的合成与表征,负载型催化剂的制备与性能测试等.其次,总结了双金属催化剂在其他加氢反应,如丙烯醛C=O双键的选择性加氢,苯的低温加氢,以及乙炔的选择性加氢等反应中的应用.最后,讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
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Carsten Schröder Philipp A. Haugg Ann-Katrin Baumann Marvin C. Schmidt Jan Smyczek Prof. Dr. Swetlana Schauermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):17240-17254
We present a mechanistic study on the formation of an active ligand layer over Pd(111), turning the catalytic surface highly active and selective in partial hydrogenation of an α,β-unsaturated aldehyde acrolein. Specifically, we investigate the chemical composition of a ligand layer consisting of allyl cyanide deposited on Pd(111) and its dynamic changes under the hydrogenation conditions. On pristine surface, allyl cyanide largely retains its chemical structure and forms a layer of molecular species with the CN bond oriented nearly parallel to the underlying metal. In the presence of hydrogen, the chemical composition of allyl cyanide strongly changes. At 100 K, allyl cyanide transforms to unsaturated imine species, containing the C=C and C=N double bonds. At increasing temperatures, these species undergo two competing reaction pathways. First, the C=C bond become hydrogenated and the stable N-butylimine species are produced. In the competing pathway, the unsaturated imine reacts with hydrogen to fully hydrogenate the imine group and produce butylamine. The latter species are unstable under the hydrogenation reaction conditions and desorb from the surface, while the N-butylimine adsorbates formed in the first reaction pathway remain adsorbed and act as an active ligand layer in selective hydrogenation of acrolein. 相似文献
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Dr. Soumyadeep Chakrabortty Prof. Dr. Bas de Bruin Prof. Dr. Johannes G. de Vries 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(10):e202315773
Asymmetric hydrogenation finds widespread application in academia and industry. And indeed, a number of processes have been implemented for the production of pharma and agro intermediates as well as flavors & fragrances. Although these processes are all based on the use of late transition metals as catalysts, there is an increasing interest in the use of base metal catalysis in view of their lower cost and the expected different substrate scope. Catalysts based on cobalt have already shown their potential in enantioselective hydrogenation chemistry. This review outlines the impressive progress made in recent years on cobalt-catalyzed asymmetric hydrogenation of different unsaturated substrates. We also illustrate the ligand dependent substrate specificity as well as the mechanistic variability in detail. This may well guide further catalyst development in this research area. 相似文献
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简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
14.
简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
15.
简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
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简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
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简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
18.
简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
19.
简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
20.
简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献