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copper catalyst

Niklas O Thiel, Johannes F Teichert
An air-stable and preactivated copper(i) hydroxide/N-heteroyclic carbene (NHC) complex for alkyne semihydrogenations is reported. Next to an enhanced practicability of the process, the resulting alkenes are obtained with high Z-selectivities and no overreduction to the corresponding alkanes.
October 26, 2016: Organic & Biomolecular Chemistry
Maud Bollenbach, Patrick Wagner, Pedro G V Aquino, Jean-Jacques Bourguignon, Frédéric Bihel, Christophe Salomé, Martine Schmitt
A copper-catalyzed Ullmann-type amination with primary amines in water with a combination of copper(II) triflate [Cu(OTf)2 ], dipivaloylmethane, and d-glucose is reported. The mild conditions and the use of an inexpensive catalyst as well as a renewable feedstock (d-glucose and the surfactant TPGS-750-M, which is derived from vitamin E) make this protocol a safe and convenient strategy for efficient C-N bond formation. This easy-to-handle procedure is extremely competitive compared to palladium-based reactions and may be used to synthesize N-containing molecules, such as drugs or organic light-emitting diodes (OLEDs)...
October 26, 2016: ChemSusChem
Andrew Gross, Raoudha Haddad, Christophe Travelet, Eric Reynaud, Pierre Audebert, Redouane Borsali, Serge Cosnier
The controlled self-assembly of precise and well-defined photochemically and electrochemically active carbohydrate-coated nanoparticles offers the exiting prospect of biocompatible catalysts for energy storage/conversion and biolabeling applications. Here an aqueous nanoparticle system has been developed with a versatile outer layer for host-guest molecule encapsulation via β-cyclodextrin inclusion complexes. A β-cyclodextrin modified polystyrene polymer was first obtained by copper nanopowder "click chemistry"...
October 25, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Mohammad Navid Soltani Rad
An ultrasonic promoted facile and convenient one-pot three-component procedure for the synthesis of 2H-indazole derivatives using copper-doped silica cuprous sulphate (CDSCS) as a heterogeneous nano-catalyst has been described. In this approach, ultrasonic mediated reaction of different substituted 2-bromobenzaldehydes, structurally diverse primary amines, and tetrabutylammonium azide (TBAA) as an azide source in the presence of CDSCS in DMSO at room temperature furnishes 2H-indazoles in good to excellent yields...
January 2017: Ultrasonics Sonochemistry
Hossein Naeimi, Rahele Shaabani
A facile one pot three component reaction of alkyl halides, sodium azide with terminal alkynes can be catalyzed by functionalized graphene oxide copper (I) complex under ultrasonic irradiation at room temperature. In this protocol, the 1,4-disubstituted 1,2,3-triazoles were afforded as target pure products in excellent yields and short reaction times. The prepared catalyst has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), Energy Dispersive X-ray (EDX) and field emission scanning electron microscopy (FE-SEM) techniques...
January 2017: Ultrasonics Sonochemistry
Meng-Juan Zhang, Hong-Xi Li, Hai-Yan Li, Jian-Ping Lang
Solvothermal reactions of 5-phenylpyrimidine-2-thiol (5-phpymtH) with equimolar CuBr afforded one hexanuclear cluster [Cu6(μ3-5-phpymt)6] (1) along with a tetranuclear by-product [{(Cu2Br)(μ-5-phpymtH)}(μ3-5-phpymt)]2 (2). A two dimensional (2D) polymer [Cu4(μ5-5-phpymt)2(μ-Br)2]n (3) was isolated from the reaction of 5-phpymtH with two equiv. of CuBr. Analogous reactions of 5-phpymtH with one or four equiv. of CuI produced one tetranuclear cluster [{Cu2(μ-5-phpymtH)(μ-5-phpymt)}(μ3-I)]2 (4) and one 2D polymer [Cu6I2(μ4-I)2(μ4-5-phpymt)2]n (5)...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Jian-Cheng Wang, Yu-Hong Hu, Gong-Jun Chen, Yu-Bin Dong
Two copper-loaded MOF materials, namely Cu(ii)@Ui-O-66-NH2 (1) and Cu(0)@UiO-66-NH2 (2), are reported. They can, respectively, serve as highly efficient heterogeneous catalysts for olefin oxidation and hydrogenation under mild conditions. Complete styrene hydrogenation occurs in 15 min at ambient temperature with quantitative yield.
October 20, 2016: Chemical Communications: Chem Comm
Kodai Kato, Koji Hirano, Masahiro Miura
A copper-catalyzed regioselective and stereospecific aminoboration of vinylsilanes with bis(pinacolato)diboron (pinB-Bpin) and hydroxylamines has been developed. In the presence of a CuCl/MeO-dppbz catalyst, the boryl group and amino group are incorporated at the β position and α position, respectively, and the corresponding β-boryl-α-aminosilanes are obtained with good diastereoselectivity. The boryl group is a good latent functional group, and subsequent manipulations provide a variety of β-functionalized α-aminosilanes of great potential in medicinal chemistry...
October 18, 2016: Angewandte Chemie
Jialei Du, Jianying Wang, Lvlv Ji, Xiaoxiang Xu, Zuofeng Chen
Although significant progress has been made recently, copper-based materials had long been considered to be ineffective catalysts toward hydrogen evolution reaction (HER), in most cases, requiring high overpotentials more than 300 mV. We report here that a Cu(0)-based nanoparticle film electrodeposited in situ from a Cu(II) oxime complex can act as a highly active and robust HER electrocatalyst in neutral phosphate buffer solution. The as-prepared nanoparticle film is of poor crystallization, which incorporates significant amounts of oxime ligand residues and buffer anions PO43-...
October 17, 2016: ACS Applied Materials & Interfaces
Sebastián Miranda-Rojas, Paulina Sierra-Rosales, Alvaro Muñoz-Castro, Ramiro Arratia-Pérez, José Heráclito Zagal, Fernando Mendizábal
The need of deeper insights regarding the inner working of catalysts represents a current challenge in the search of new ways to tune their activities towards new chemical transformations. Within this field, metallophthalocyanines-based (MPc) electrocatalysis has gained tremendous attention due to their versatility, low cost, great stability and excellent turn-over properties. In this concern, here we present a quantum chemical study of the formation of supramolecular complexes based on the adsorption of MPcs on gold substrates, and the effect of the substrate on their electrocatalytic properties...
October 17, 2016: Physical Chemistry Chemical Physics: PCCP
James R Wright, James D Crowley, Nigel T Lucas
Hexaphenylbenzene (HPB) and hexa-peri-hexabenzocoronene-(HBC) functionalised 1,2,3-triazoles have been synthesised using an optimised copper(i)-catalysed azide-alkyne cycloaddition (CuAAC) reaction. The coordination chemistry of these ligands was explored through the synthesis of the respective palladium(ii) complexes and their activity as catalysts in the Suzuki-Miyaura reaction assessed.
October 17, 2016: Chemical Communications: Chem Comm
Scott W Krabbe, Vincent S Chan, Thaddeus S Franczyk, Shashank Shekhar, José G Napolitano, Carmina A Presto, Justin A Simanis
A Cu-catalyzed synthesis of amides from alcohols and secondary amines using the oxygen in air as the terminal oxidant has been developed. The methodology is operationally simple requiring no high pressure equipment or potentially explosive O2 balloons. The commercially available, non-precious metal catalyst, Cu(phen)Cl2, in conjunction with di-tert-butyl hydrazine dicarboxylate and an inorganic base provides a variety of benzamides in moderate to excellent yields. The pKa of amine conjugate acid and electronics of alcohol were shown to impact the selection of base for optimal reactivity...
October 14, 2016: Journal of Organic Chemistry
Fengxiang Zhu, Yahui Li, Zechao Wang, Xiao-Feng Wu
A novel procedure on the carbonylative synthesis of chromenones has been developed. With simple phenols and internal alkynes as the substrates, various chromenones were isolated in moderate to good yields with excellent regioselectivity and functional-group tolerance by using iridium as the catalyst and copper as the promotor at atmospheric pressure. Notably, this is the first example on carbonylative annulation of simple phenols and alkynes.
October 12, 2016: Angewandte Chemie
Keigo Aihara, Mao Akiyama, Takashi Deguchi, Masashi Tanaka, Rina Hagiwara, Masakazu Iwamoto
A wool-like copper electrode used to produce non-thermal plasma functioned as an efficient catalyst for ammonia production from N2 and H2 under atmospheric pressure without heating. The catalytic activity increased as the experiments were repeated. The yield of ammonia at H2/N2 = 3 was 3.5%. The intensity of the emission spectra of N2*(C-B) bands was correlated with the ammonia synthesis rate.
October 6, 2016: Chemical Communications: Chem Comm
Krishna K Sharma, Meenakshi Mandloi, Rahul Jain
We report regioselective N(1)-arylation of protected histidine using copper(i) iodide as a catalyst, trans-N,N'-dimethylcyclohexane-1,2-diamine as a ligand and readily available aryl iodides as coupling partners under microwave irradiation at 130 °C for 40 min. The reaction provides rapid access to electron-donating, electron-withdrawing and bulky group substituted N-arylated histidines in high yields, including previously inaccessible N-heteroaryl histidines. These N(1)-(hetero)aryl histidines are promising building blocks in peptide-based drug design and discovery...
September 26, 2016: Organic & Biomolecular Chemistry
Zhixian Li, Yi Ding, Shaomin Li, Yanbin Jiang, Zheng Liu, Jun Ge
A nature-inspired approach to encapsulate enzymes in spindle-like copper hydroxysulfate nanocrystals was developed by a biomimetic mineralization process. Several types of enzymes including glucose oxidase (GOx), horseradish peroxidase (HRP), Candida antarctica lipase B (CALB) and cytochrome c (Cyt c) were successfully encapsulated in copper hydroxysulfate nanocrystals quickly (within 1 hour) with maintained or even greatly enhanced catalytic efficiencies (kcat/KM of Cyt c showed a 143-fold increase) and high stabilities, demonstrating the feasibility of utilizing copper hydroxysulfate nanocrystals as a novel type of nanocarrier for enzyme immobilization...
October 14, 2016: Nanoscale
Dimitrios A Giannakoudakis, Nikolina A Travlou, Jeff Secor, Teresa J Bandosz
A unique composite of the copper-based metal-organic framework (Cu-benzene tricarboxylic acid (BTC)) with oxidized graphitic carbon nitride nanospheres is synthesized. For comparison, a hybrid material consisting of g-C3 N4 and Cu-BTC is also obtained. Their surface features are analyzed using Fourier transform infrared spectroscopy, X-ray diffraction, sorption of nitrogen, thermal analysis, scanning electron microscopy, photoluminescence, and diffuse reflectance UV-Vis spectroscopy. The results suggest that the formed nanospheres of oxidized g-C3 N4 act as linkers between the copper sites, playing a crucial role in the composite building process...
October 6, 2016: Small
Júlia Barabás, Tibor Höltzl
Highly active catalytic clusters are observed during the reaction mechanism study of the copper cluster Cux (x = 4-15) catalyzed N2O + CO → N2 + CO2 reaction. It was shown that N2O adsorbs on the copper cluster without an activation barrier and the nitrogen-oxygen bond is broken during the next step. The analysis of the chemical bonding showed that the oxide ion formation is an important driving force of the reaction. Among the different clusters Cu12 was the most active as the nitrogen-oxygen bond is cleaved without an energy barrier, while the nitrogen molecule is eliminated...
October 5, 2016: Journal of Physical Chemistry. A
Biswadip Banerji, K Chandrasekhar, Sunil Kumar Killi, Sumit Kumar Pramanik, Pal Uttam, Sudeshna Sen, Nakul Chandra Maiti
'Click reactions' are the copper catalysed dipolar cycloaddition reaction of azides and alkynes to incorporate nitrogens into a cyclic hydrocarbon scaffold forming a triazole ring. Owing to its efficiency and versatility, this reaction and the products, triazole-containing heterocycles, have immense importance in medicinal chemistry. Copper is the only known catalyst to carry out this reaction, the mechanism of which remains unclear. We report here that the 'click reactions' can also be catalysed by silver halides in non-aqueous medium...
September 2016: Royal Society Open Science
Roy van den Berg, Gonzalo Prieto, Gerda Korpershoek, Lars I van der Wal, Arnoldus J van Bunningen, Susanne Lægsgaard-Jørgensen, Petra E de Jongh, Krijn P de Jong
For decades it has been debated whether the conversion of synthesis gas to methanol over copper catalysts is sensitive or insensitive to the structure of the copper surface. Here we have systematically investigated the effect of the copper particle size in the range where changes in surface structure occur, that is, below 10 nm, for catalysts with and without zinc promotor at industrially relevant conditions for methanol synthesis. Regardless of the presence or absence of a zinc promotor in the form of zinc oxide or zinc silicate, the surface-specific activity decreases significantly for copper particles smaller than 8 nm, thus revealing structure sensitivity...
October 5, 2016: Nature Communications
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