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941.
Dr. Xu Quan Dr. Sutthichat Kerdphon Bram B. C. Peters Dr. Janjira Rujirawanich Dr. Suppachai Krajangsri Dr. Jira Jongcharoenkamol Prof. Pher G. Andersson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13311-13316
Novel bidentate N-heterocyclic carbene-phosphine iridium complexes have been synthesized and evaluated in the hydrogenation of ketones. Reported catalytic systems require base additives and, if excluded, need elevated temperature or high pressure of hydrogen gas to achieve satisfactory reactivity. The developed catalysts showed extremely high reactivity and good enantioselectivity under base-free and mild conditions. In the presence of 1 mol % catalyst under 1 bar hydrogen pressure at room temperature, hydrogenation was complete in 30 minutes giving up to 96 % ee. Again, this high reactivity was achieved in additive-free conditions. Mechanistic experiments demonstrated that balloon pressure of hydrogen was sufficient to form the activate species by reducing and eliminating the 1,5-cyclooctadiene ligand. The pre-activated catalyst was able to hydrogenate acetophenone with 89 % conversion in 5 min. 相似文献
942.
We present herein a new nanocatalyst, namely binary CuPt alloy nanoparticles (NPs) supported on reduced graphene oxide (CuPt‐rGO), as a highly active heterogeneous catalyst for the transfer hydrogenation (TH) protocol that is demonstrated to be applicable over the reduction of various unsaturated organic compounds (olefins, aldehydes/ketones and nitroarenes) in aqueous solutions at room temperature. CuPt alloy NPs were synthesized by the co‐reduction of metal (II) acetylacetonates by borane‐tert‐butylamine (BTB) complex in hot oleylamine (OAm) solution and then assembled on reduced graphene oxide (rGO) via ultrasonic‐assisted liquid phase self‐assembly method. The structure of yielded CuPt NPs and CuPt‐rGO nanocatalyst were characterized by TEM, XRD and ICP‐MS. The activity of Cu7Pt3‐rGO nanocatalysts were then tested for the THs that were conducted in a commercially available high‐pressure tube using water as sole solvent and ammonia borane as a hydrogen donor at room temperature. The presented catalytic TH protocol was successfully applied over nitroarenes, olefines and aldehydes/ketones, and all the tested compounds were converted to corresponding reduction products with the yields reaching up to 99% under ambient conditions. Moreover, the Cu7Pt3‐rGO nanocatalyst was also reusable in the TH by providing 99% yield after five consecutive runs in TH of nitrobenzene as an example. 相似文献
943.
Chengshan Dai Dr. Ying Zhang Junnan Chen Dr. Xia Zhong Dr. Liyun Zhang Prof. Dr. Bingsen Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(34):e202200199
Selective hydrogenation of substituted nitroaromatic compounds is an extremely important and challenging reaction. Supported metal catalysts attract much attention in this reaction because the properties of metal nanoparticles (NPs) can be modified by the nature of the support. Herein, the support morphology on the catalytic performance of selective hydrogenation of 3-nitrostyrene to 3-vinylaniline was investigated. Pt NPs supported on octadecahedral α-Fe2O3 supports with a truncated hexagonal bipyramid shape (Pt/α-Fe2O3-O) and rod-shaped α-Fe2O3 supports (Pt/α-Fe2O3-R) were prepared by glycol reduction method. Detailed characterizations reveal that the electronic structure and dispersion of Pt NPs can be modified by the supports. The Pt/α-Fe2O3-O catalyst exhibited superior catalytic performance for hydrogenation of 3-nitrostyrene because of its low coordinated Pt sites and the small Pt NPs size, which is benefit from the high-index exposed surfaces of truncated hexagonal bipyramid-shaped α-Fe2O3 support. The structural evolution during the catalytic reaction was investigated in detail by identical location transmission electron microscopy (IL-TEM) method, which found that the high cycling activity of Pt/α-Fe2O3-O catalyst during the cycle experiment results from the stability of Pt NPs. 相似文献
944.
Dr. Coralie Gelis Arne Heusler Dr. Zackaria Nairoukh Prof. Dr. Frank Glorius 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(62):14090-14094
Transfer hydrogenation reactions are of great interest to reduce diverse molecules under mild reaction conditions. To date, this type of reaction has only been successfully applied to alkenes, alkynes and polarized unsaturated compounds such as ketones, imines, pyridines, etc. The reduction of benzene derivatives by transfer hydrogenation has never been described, which is likely due to the high energy barrier required to dearomatize these compounds. In this context, we have developed a catalytic transfer hydrogenation reaction for the reduction of benzene derivatives and heteroarenes to form complex 3-dimensional scaffolds bearing various functional groups at room temperature without needing compressed hydrogen gas. 相似文献
945.
946.
947.
A series of Pd and Pd‐Ga bimetallic catalysts were prepared by a co‐impregnation method for 2‐ethylanthraquinone (EAQ) hydrogenation to produce hydrogen peroxide. Compared with 0.6Pd catalyst, the hydrogenation efficiency of 0.6Pd1.2Ga catalyst (11.9 g L?1) increases by 32.2%, and the stability of 0.6Pd1.2Ga catalyst is also higher than that of 0.6Pd catalyst. The structures of the samples were determined by N2 adsorption–desorption, ICP, XRD, CO chemisorption, TEM, H2‐TPR, in situ CO‐DRIFTS and XPS. The results suggest that incorporation of Ga species improves Pd dispersion and generates a strong interaction between Ga2O3 and Pd interface or between Pd and support. DFT calculation results indicate that the strong adsorption of carbonyl group on Ga2O3/Pd interface facilitates the activation of EAQ and promotes the hydrogenation efficiency. 相似文献
948.
Sevda Dehghani Samahe Sadjadi Naeimeh Bahri‐Laleh Mehdi Nekoomanesh‐Haghighi Albert Poater 《应用有机金属化学》2019,33(5)
Taking advantage of computational chemistry, the best diamine for the synthesis of a multi‐dentate ligand from the reaction with 3‐(trimethoxysilyl) propylisocyanate (TEPI) was selected. Actually, predictive Density Functional Theory (DFT) calculations provided the right diamino chain, i.e. ethylenediamine, capable to sequester a palladium atom, together with the relatively polar solvent toluene, and then undergo the experiments as a selective catalytic agent. The ligand was then prepared and applied for the decoration of the halloysite (Hal) outer surface to furnish an efficient support for the immobilization of Pd nanoparticles. The resulting catalyst exhibited high catalytic activity for hydrogenation of nitroarenes. Moreover, it showed high selectivity towards nitro functional group. The study of the catalyst recyclability confirmed that the catalyst could be recycled for several reaction runs with only slight loss of the catalytic activity and Pd leaching. Hot filtration test also proved the heterogeneous nature of the catalysis. 相似文献
949.
Dr. Kathrin Junge Veronica Papa Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):122-143
Non-noble metal catalysts based on pincer type compounds are of special interest for organometallic chemistry and organic synthesis. Next to iron and manganese, currently cobalt–pincer type complexes are successfully applied in various catalytic reactions. In this review the recent progress in (de)hydrogenation, transfer hydrogenation, hydroboration and hydrosilylation as well as dehydrogenative coupling reactions using cobalt–pincer complexes is summarised. 相似文献
950.
This report successfully demonstrates the synthesis and application of palladium stearates. It was found that the branching of the carboxylate anion of metal precursors could influence the size and shape of palladium nanoparticles (PdNPs). Worm‐like nanowires were formed when using the branched isomer palladium isostearate (PdISt2), while triangular nanoparticles were produced in a majority when using the normal form: palladium stearate (PdSt2). Furthermore, when applying CO2 to the system, both types of PdNPs transformed into more spherical shapes with smaller sizes. The formation of carbamates from the amine stabilizer with CO2 could prevent the further growth and aggregation of PdNPs. The PdNPs were tested as catalysts for the hydrogenation of styrene, and higher catalytic activities were achieved with PdNPs that were prepared with the assistance of CO2. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献