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copper catalyst

Wenkui Lu, Hui Xu, Zengming Shen
An efficient protocol for copper-catalyzed aromatic C-H alkoxylation with alcohols has been developed under aerobic conditions. The protocol provides a complementary method to couple arenes and alcohols to furnish aromatic ethers. The advantages of this method are the employment of a cheap Cu(OAc)2 catalyst, oxygen as the terminal oxidant and alcohol as both an alkoxy reagent and a solvent. Notably, the catalytic amount of benzoic acid plays a significant role in this transformation.
January 18, 2017: Organic & Biomolecular Chemistry
Jun Li, Hai-Yan Tao, Chun-Jiang Wang
A highly efficient enantioselective nitroso Diels-Alder reaction of 6-methyl-2-nitroso pyridine with various 1,3-dienes was successfully developed using a Cu(i)/(S)-TF-BiphamPhos complex as the catalyst. For most of the cyclic dienes, synthetically important heterocyclic 3,6-dihydro-1,2-oxazines were obtained in high yields with excellent regio-, diastereo- and enantioselectivities. Acyclic 2-silyloxy-1,3-diene also worked well in the reaction.
January 18, 2017: Chemical Communications: Chem Comm
Taekyung Ryu, Nak Ho Ahn, Seungwan Seo, Jung Cho, Hyojun Kim, Donghui Jo, Gi Tae Park, Pyung Soon Kim, Chang Hwan Kim, Elliott L Bruce, Paul A Wright, In-Sik Nam, Suk Bong Hong
Diesel engine technology is still the most effective solution to meet tighter CO2 regulations in the mobility and transport sector. In implementation of fuel-efficient diesel engines, the poor thermal durability of lean nitrogen oxides (NOx ) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high-silica LTA zeolites are demonstrated to exhibit excellent activity maintenance for NOx reduction with NH3 under vehicle simulated conditions even after hydrothermal aging at 900 °C, a critical temperature that the current commercial Cu-SSZ-13 catalyst cannot overcome owing to thermal deactivation...
January 18, 2017: Angewandte Chemie
Yifan Li, Fan Cui, Michael B Ross, Dohyung Kim, Yuchun Sun, Peidong Yang
Copper is uniquely active for the electrocatalytic reduction of carbon dioxide (CO2) to products beyond carbon monoxide, such as methane (CH4) and ethylene (C2H4). Therefore, understanding selectivity trends for CO2 electrocatalysis on copper surfaces is critical for developing more efficient catalysts for CO2 conversion to higher order products. Herein, we investigate the electrocatalytic activity of ultrathin (diameter ~20 nm) five-fold twinned copper nanowires (Cu NWs) for CO2 reduction. These Cu NW catalysts were found to exhibit high CH4 selectivity over other carbon products, reaching 55% Faradaic efficiency (F...
January 17, 2017: Nano Letters
Rahul Kisan Kawade, Rai-Shung Liu
One-pot cascade annulations among nitrosoarenes, alkenes, and N-hydroxyallylamines have been achieved with CuCl/O2 catalysts, forming fused oxazinane/isoxazolidine heterocycles with excellent diastereoselectivity (d.r. >20:1). To enhance the synthetic utility, we developed a successive cleavage of the two N-O bonds of the resulting heterocycles. A mechanism involving dipolar [3+2] cycloadditions of nitrone intermediates with their tethered alkenes is postulated for formation of these heterocycles.
January 16, 2017: Angewandte Chemie
Eric Wimmer, Sophie Borghèse, Aurélien Blanc, Valérie Bénéteau, Patrick Pale
Similarly to polymer-supported assisted synthesis (PSAS), organic synthesis could be envisaged being performed by using zeolites, native or metal-doped, as heterogeneous catalysts. To illustrate this unprecedented Zeolite-Based Organic Synthesis (ZeoBOS), the total synthesis of acortatarin A was achieved through a novel strategy and using five out of eleven synthetic steps catalyzed by H- or metal-doped zeolites as catalysts. Notably, the formation of an yne-pyrrole intermediate with a copper-doped zeolite and the spiroketalization of an alkyne diol with a silver-doped zeolite have been developed as key steps of the synthesis...
November 6, 2016: Chemistry: a European Journal
Muhammad Usman, Zhi-Hui Ren, Yao-Yu Wang, Zheng-Hui Guan
A new Cu-catalyzed efficient protocol is described for the transformation of oximes to the corresponding carbonate derivatives. Diisopropyl azodicarboxylate acted as a selective new precursor for the synthesis of oxime carbonates in high yields. The O-H bond cleavage and O-C bond formation occur in the presence of a copper catalyst providing a synthetically useful process, which tolerates a wide range of functional groups.
January 16, 2017: Organic & Biomolecular Chemistry
Aozhen Xie, Ningning Xuan, Kun Ba, Zhengzong Sun
Graphene, the sp2 carbonaceous two dimensional (2D) material, is gaining more attentions in recent electrochemical studies. However, this atomic thick electrode usually suffers with surface contamination and poor electrochemical endurance. To overcome the drawbacks, we developed a PMMA-assisted, flipped transfer method to fabricate the graphene electrode with pristine surface and prolonged lifetime in hydrogen evolution reaction (HER). The HER performances of the single-layer graphene (SLG) were evaluated on various insulating and conductive substrates, including SiO2, polymers, SLG, highly oriented pyrolytic graphite (HOPG), and copper...
January 12, 2017: ACS Applied Materials & Interfaces
Jian-Siang Poh, Szabolcs Makai, Timo von Keutz, Duc N Tran, Claudio Battilocchio, Patrick Pasau, Steven V Ley
We report herein the asymmetric coupling of flow-generated unstabilized diazo compounds and propargylated amine derivatives, using a new pyridinebis(imidazoline) ligand, a copper catalyst and base. The reaction proceeds rapidly, generating chiral allenes in 10-20 minutes with high enantioselectivity (89-98 % de/ee), moderate yields and a wide functional group tolerance.
January 11, 2017: Angewandte Chemie
Tetsuaki Fujihara, Ayumi Sawada, Tatsuya Yamaguchi, Yosuke Tani, Jun Terao, Yasushi Tsuji
The boraformylation of allenes with B2 (pin)2 and a formate ester as boron and formyl source, respectively, proceeds in the presence of a copper catalyst. The reaction selectively affords the corresponding β-boryl β,γ-unsaturated aldehydes in good to high yields. Furthermore, the silaformylation of allenes was achieved with a formate ester and PhMe2 Si-B(pin) as the silicon source.
January 11, 2017: Angewandte Chemie
Da-Wei Zhang, Yu-Min Zhang, Jing Li, Tian-Qi Zhao, Qiang Gu, Feng Lin
An efficient synthesis of 1,4-disubstituted 1,2,3-triazole derivatives was studied. 1,4-Disubstituted 1,2,3-triazoles containing isoxazole and thymidine structures were synthesized in 84-96% yields starting from various terminal isoxazole ether alkynes and β-thymidine azide derivatives via a 1,3-dispolar cycloaddition using copper acetate, sodium ascorbate as the catalyst under ultrasonic assisted condition. All the target compounds were characterized by HRMS, FT-IR, (1)H NMR and (13)C NMR spectroscopy. Furthermore, the quorum sensing inhibitory activities of synthesized compounds were evaluated with Chromobacterium violaceum (C...
May 2017: Ultrasonics Sonochemistry
Roberta Lucchetti, Antonietta Siciliano, Laura Clarizia, Danilo Russo, Ilaria Di Somma, Francesco Di Natale, Marco Guida, Roberto Andreozzi, Raffaele Marotta
The photocatalytic removal of nitrate with simultaneous hydrogen generation was demonstrated using zero-valent nano-copper-modified titania (P25) as photocatalyst in the presence of UV-A-Vis radiation. Glycerol, a by-product in biodiesel production, was chosen as a hole scavenger. Under the adopted experimental conditions, a nitrate removal efficiency up to 100% and a simultaneous hydrogen production up to 14 μmol/L of H2 were achieved (catalyst load = 150 mg/L, initial concentration of nitrate = 50 mg/L, initial concentration of glycerol = 0...
January 7, 2017: Environmental Science and Pollution Research International
Sipei Li, Hee Sung Chung, Antonina Simakova, Zongyu Wang, Sangwoo Park, Liye Fu, Devora Cohen-Karni, Saadyah Averick, Krzysztof Matyjaszewski
The synthesis of a sulfoxide-based water-soluble polymer, poly(2-(methylsulfinyl)ethyl acrylate) (polyMSEA), a polymeric analogue of DMSO, by atom transfer radical polymerization (ATRP) is reported. Well-defined linear polymers were synthesized using relatively low amounts of copper catalyst (1000 or 100 ppm). Two types of star polymers were synthesized by either an "arm-first" approach or a "core-first" approach using a biodegradable β-cyclodextrin core. The glass transition temperatures of both the linear polymer (16 °C) and star polymer (32 °C) were determined by differential scanning calorimetry (DSC)...
January 5, 2017: Biomacromolecules
Jessica M de Ruiter, Francesco Buda
The investigation of the catalytic mechanism of homogeneous water oxidation catalysts remains an active field of research. When examining catalytic steps theoretically, it is often difficult to account for the transfer of protons and electrons from step to step. To this end, a closed system approach is proposed which includes both proton and electron acceptors in the simulation box to allow for the description of proton-coupled electron transfer processes. Using Car-Parrinello Molecular Dynamics, a mononuclear copper water oxidation catalyst Cu(bpy)(OH)2 was used as a model system to explore this closed system approach...
January 5, 2017: Physical Chemistry Chemical Physics: PCCP
Enna Ha, Wei Liu, Luyang Wang, Ho-Wing Man, Liangsheng Hu, Shik Chi Edman Tsang, Chris Tsz-Leung Chan, Wai-Ming Kwok, Lawrence Yoon Suk Lee, Kwok-Yin Wong
Hydrogen generation from water using noble metal-free photocatalysts presents a promising platform for renewable and sustainable energy. Copper-based chalcogenides of earth-abundant elements, especially Cu2ZnSnS4 (CZTS), have recently arisen as a low-cost and environment-friendly material for photovoltaics and photocatalysis. Herein, we report a new heterostructure consisting of CZTS nanoparticles anchored onto a MoS2-reduced graphene oxide (rGO) hybrid. Using a facile two-step method, CZTS nanoparticles were in situ grown on the surface of MoS2-rGO hybrid, which generated high density of nanoscale interfacial contact between CZTS and MoS2-rGO hybrid...
January 3, 2017: Scientific Reports
Changjian Zhou, Richard Senegor, Zachary Baron, Yihan Chen, Salahuddin Raju, Anshul A Vyas, Mansun Chan, Yang Chai, Cary Y Yang
Carbon nanotubes (CNTs) and graphene are potential candidates for future interconnect materials. CNTs are promising on-chip via interconnect materials due to their readily formed vertical structures, their current-carrying capacity, which is much larger than existing on-chip interconnect materials such as copper and tungsten, and their demonstrated ability to grow in patterned vias with sub-50 nm widths; meanwhile, graphene is suitable for horizontal interconnects. However, they both present the challenge of having high-resistance contacts with other conductors...
February 3, 2017: Nanotechnology
Huang Qiu, Yifan Deng, Kostiantyn O Marichev, Michael P Doyle
Three catalyst-dependent divergent reaction pathways for reactions of propargyl aryldiazoacetates are disclosed. Transition metal catalysts including those of rhodium(II), palladium(0 and II), silver(I), mercury(II), copper(I and II), platinum(II) and cationic gold(I) are effective for reactions that proceed through dinitrogen extrusion, carbene/alkyne metathesis, and aromatic substitution to form fused indeno-furanones, and use of tetrakis(acetonitrile)copper(I) provides indeno-furanones in the highest product yields...
December 28, 2016: Journal of Organic Chemistry
Debkumar Nandi, Abu Taher, Rafique Ul Islam, Samarjeet Siwal, Meenakshi Choudhary, Kaushik Mallick
The composite framework of graphitic carbon nitride (gCN) supported copper nanoparticle can act as a high-performance photoreactor for the synthesis of 1,2,3-triazole derivatives under light irradiation in the absence of alkaline condition. The photoactivity of gCN originates from an electron transition from the valence band to the conduction band, in the presence of photon energy, and the hot electron acts as a scavenger of the terminal proton of the alkyne molecule to facilitate the formation of copper acetanilide complex...
November 2016: Royal Society Open Science
Ardiansyah Taufik, Rosari Saleh
A facile sol-gel method was adopted to synthesize iron(II,III) oxide/zinc oxide/copper(II) oxide (Fe3O4/ZnO/CuO) nanocomposites with various CuO loadings at a low temperature. The prepared nanocomposites were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV-Vis spectroscopy, vibrating sample magnetometry, and Brunauer-Emmett-Teller (BET) surface area analyses. The photosonocatalytic properties of the nanocomposites were tested by methylene blue removal in aqueous solutions under the combination of UV or visible light and ultrasound...
December 12, 2016: Journal of Colloid and Interface Science
Dennis Palagin, Amy J Knorpp, Ana B Pinar, Marco Ranocchiari, Jeroen A van Bokhoven
Copper-containing zeolites exhibit high activity in the direct partial oxidation of methane into methanol at relatively low temperatures. Di- and tricopper species have been proposed as active catalytic sites, with recent experimental evidence also suggesting the possibility of the formation of larger copper oxide species. Using density functional theory based global geometry optimization, we were able to identify a general trend of the copper oxide cluster stability increasing with size. For instance, the identified ground-state structures of tetra- and pentamer copper clusters of CunOn(2+) and CunOn-1(2+) stoichiometries embedded in an 8-ring channel of mordenite exhibit higher relative stability compared to smaller clusters...
January 19, 2017: Nanoscale
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