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https://www.readbyqxmd.com/read/27906507/palladium-ii-catalysed-oxidative-aminocarbonylation-for-the-synthesis-of-2-ynamides-addressing-the-challenges-of-solvents-and-gas-mixtures
#1
Nicola Hughes, Clare Brown, Andrew Irwin, Qun Cao, Mark Muldoon
2-Ynamides can be synthesised via Pd(II) catalysed oxidative carbonylation, utilizing low catalyst loadings. A variety of alkynes and amines can be used to afford 2-ynamides in high yields, whilst overcoming the drawbacks associated with previous oxidative methods which rely on dangerous solvents and gas mixtures.
December 1, 2016: ChemSusChem
https://www.readbyqxmd.com/read/27906484/a-ligand-free-pt3-cluster-catalyses-the-markovnikov-hydrosilylation-of-alkynes-with-up-to-106-turnover-frequencies
#2
Avelino Corma, Antonio Leyva, Miguel Angel Rivero
The Pt-catalysed hydrosilylation of alkynes is the procedure of choice to obtain vinylsilanes, and this is claimed to be the most relevant application of Pt in organic synthesis. More than half a century after its discovery, only -vinylsilanes (anti-Markovnikov addition) are obtained with simple Pt catalysts, while -vinylsilanes (Markovnikov addition) remain elusive compounds. Here we report that Pt3 clusters, in part-per-million (ppm) amounts, catalyse the Markovnikov hydrosilylation of terminal alkynes to give a wide variety of -vinylsilanes in reasonable isolated yields and with turnover frequencies that can reach up to one million per hour...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27906482/three-dimensional-super-branched-pdcu-nanoarchitectures-exposed-on-controlled-crystal-facets
#3
Muhammad Iqbal, Cuiling Li, Jung Ho Kim, Saad M Alshehri, Tsuruo Nakayama, Yusuke Yamauchi
Despite the great success of controlled synthesis of metal nanocrystals with various sizes and morphologies, an efficient one-pot approach to preparing well-organized three-dimensional (3D) structures with unique facets exposed remains a great challenge. Herein, we report a unique 3D nanoarchitecture for PdCu alloy, created by a simple chemical reduction method, in which nanosized octahedral PdCu nanocrystals are directly assembled into 3D super-branched structures. Detailed investigations of its electrocatalytic performance demonstrate that the as-prepared facet-controlled PdCu super-branched nanostructures possess higher activity towards the formic acid oxidation reaction in comparison to the commercially available Pd black catalyst...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27906402/one-step-synthesis-of-ultrathin-ptxpb-nerve-like-nanowires-as-robust-catalysts-for-enhanced-methanol-electrooxidation
#4
Liang Huang, Yujie Han, Xueping Zhang, Youxing Fang, Shaojun Dong
Ultrathin PtxPb nerve-like nanowires (NNWs) with a diameter of only around 3.6 nm were synthesized by a one-step wet-chemical strategy, and they served as robust catalysts for greatly enhancing methanol electrooxidation both under acidic and alkaline conditions. Due to the high CO-poisoning tolerance, superior electrocatalytic activity and stability endowed by the Pt-Pb alloyed composition and the unique structure, the Pt3.5Pb NNWs showed the highest specific activity of 2.78 mA cm(-2) in acidic media and 6...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27905617/a-novel-ag-i-calix-4-arene-coordination-polymer-for-the-sensitive-detection-and-efficient-photodegradation-of-nitrobenzene-in-aqueous-solution
#5
Lei-Lei Liu, Jing Chen, Cai-Xia Yu, Wen-Xing Lv, Hui-Ying Yu, Xiao-Qing Cui, Lin Liu
Nitrobenzene (NB) is a widespread and highly toxic organic pollutant in water, and consequently its detection and removal have attracted considerable attention. In the present study, we designed and synthesized a novel coordination polymer, [AgL0.5(NO3)]n (1), {L = 25,26,27,28-tetra[(3-pyridylmethyl)oxy]calix[4]arene}, from AgNO3 and a tetra-pyridyl-functionalized calix[4]arene ligand, which possessed a 2D network based on [Ag4L(NO3)4] units. The 1-modified glassy carbon electrode (1/GCE) exhibited good electrocatalytic activity toward the reduction of NB, offering the selective detection of NB in a wide linear range (1-2450 μM) and a low detection limit (0...
December 1, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27905591/ceo2-modified-%C3%AE-moo3-nanorods-as-a-synergistic-support-for-pt-nanoparticles-with-enhanced-coads-tolerance-during-methanol-oxidation
#6
Yanying Liu, Chuntao Liu, Xuefeng Yu, Hannah Osgood, Gang Wu
A new type of Ce-doped α-MoO3 (Ce0.2Mo0.8O3-δ) nanorod support was synthesized using a two-step hydrothermal method. The mixed oxide solid solution was employed as a novel non-carbon support for Pt catalysts used for the methanol electrooxidation in acidic media. The ratio of Ce to Mo in the solid-solution was systematically optimized in terms of the performance as a support for methanol oxidation. Pt nanoparticles with an average diameter of 2 nm were evenly deposited on Ce0.2Mo0.8O3-δ nanorods. Compared to the Pt/MoO3 and commercial Pt/C catalysts, the optimal Pt/Ce0...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27905505/surface-protonics-promotes-catalysis
#7
R Manabe, S Okada, R Inagaki, K Oshima, S Ogo, Y Sekine
Catalytic steam reforming of methane for hydrogen production proceeds even at 473 K over 1 wt% Pd/CeO2 catalyst in an electric field, thanks to the surface protonics. Kinetic analyses demonstrated the synergetic effect between catalytic reaction and electric field, revealing strengthened water pressure dependence of the reaction rate when applying an electric field, with one-third the apparent activation energy at the lower reaction temperature range. Operando-IR measurements revealed that proton conduction via adsorbed water on the catalyst surface occurred during electric field application...
December 1, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27905488/advanced-fabrication-of-chemically-bonded-graphene-tio2-continuous-fibers-with-enhanced-broadband-photocatalytic-properties-and-involved-mechanisms-exploration
#8
Qingzhe Zhang, Nan Bao, Xinqiang Wang, Xinde Hu, Xinhan Miao, Mohamed Chaker, Dongling Ma
In this article, a novel route for the synthesis of graphene/TiO2 continuous fibers (GTF) using force-spinning combined with water vapor annealing method is reported for the first time. The morphology, structure and optical properties of the composite were fully characterized. With a single step of heat treatment process using steam at ambient conditions, we were able to initiate a series of chemical reactions, such as reduction of graphene oxide (GO), crystallization of TiO2, formation of C-Ti bond, and introduction of oxygen vacancies into TiO2...
December 1, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27905424/catalysts-silicon-added-to-life-s-toolbox
#9
(no author information available yet)
No abstract text is available yet for this article.
November 30, 2016: Nature
https://www.readbyqxmd.com/read/27904897/molecular-engineering-for-efficient-and-selective-iron-porphyrin-catalysts-for-electrochemical-reduction-of-co2-to-co
#10
Ram B Ambre, Quentin Daniel, Ting Fan, Hong Chen, Biaobiao Zhang, Lei Wang, Mårten S G Ahlquist, Lele Duan, Licheng Sun
Iron porphyrins Fe-pE, Fe-mE, and Fe-oE were synthesized and their electrochemical behavior for CO2 reduction to CO has been investigated. The controlled potential electrolysis of Fe-mE gave exclusive 65% Faradaic efficiency (FE) whereas Fe-oE achieved quasi-quantitative 98% FE (2% H2) for CO production.
December 1, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27904896/rapid-synthesis-of-ultralong-fe-oh-3-cu-oh-2-core-shell-nanowires-self-supported-on-copper-foam-as-a-highly-efficient-3d-electrode-for-water-oxidation
#11
Chun-Chao Hou, Chuan-Jun Wang, Qian-Qian Chen, Xiao-Jun Lv, Wen-Fu Fu, Yong Chen
One-dimensional core-shell nanowire materials have recently received great attention as durable catalysts for water splitting. Herein we report the facile and rapid synthesis of ultralong Fe(OH)3:Cu(OH)2 core-shell nanowires grown in situ on an open 3D electrode to function as a highly efficient electrocatalyst for water oxidation. It only requires an overpotential of ∼365 mV to reach a 10 mA cm(-2) current density in 1.0 M KOH. As far as we know, this shows the best result amongst Cu-based heterogeneous OER systems reported to date...
December 1, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27904740/from-substituent-effects-to-applications-enhancing-the-optical-response-of-a-four-component-assembly-for-reporting-ee-values
#12
Chung-Yon Lin, Michael W Giuliano, Bryan D Ellis, Scott J Miller, Eric V Anslyn
High-throughput screening for asymmetric catalysts has stimulated an interest in optically-based enantiomeric-excess (ee) sensors, primarily for their improved time and cost efficiency when compared to the standard HPLC analysis. We present herein substituent-effect studies on a recently reported Zn(II) multicomponent assembly that is used for chiral, secondary alcohol ee detemination. The systematic altering of assemblies formed from select substituted pyridyl ligands pointed to the conclusion that steric effects dominate the mode of interaction at the pyridyl 3- and 6- positions...
July 1, 2016: Chemical Science
https://www.readbyqxmd.com/read/27903763/enzyme-activation-through-the-utilization-of-intrinsic-dianion-binding-energy
#13
REVIEW
T L Amyes, M M Malabanan, X Zhai, A C Reyes, J P Richard
We consider 'the proposition that the intrinsic binding energy that results from the noncovalent interaction of a specific substrate with the active site of the enzyme is considerably larger than is generally believed. An important part of this binding energy may be utilized to provide the driving force for catalysis, so that the observed binding energy represents only what is left over after this utilization' [Jencks,W.P. (1975) Adv. Enzymol. Relat. Areas. Mol. Biol., 43: , 219-410]. The large ~12 kcal/mol intrinsic substrate phosphodianion binding energy for reactions catalyzed by triosephosphate isomerase (TIM), orotidine 5'-monophosphate decarboxylase and glycerol-3-phosphate dehydrogenase is divided into 4-6 kcal/mol binding energy that is expressed on the formation of the Michaelis complex in anchoring substrates to the respective enzyme, and 6-8 kcal/mol binding energy that is specifically expressed at the transition state in activating the respective enzymes for catalysis...
November 29, 2016: Protein Engineering, Design & Selection: PEDS
https://www.readbyqxmd.com/read/27902876/asymmetric-synthesis-of-optically-active-spirocyclic-indoline-scaffolds-applying-an-enantioselective-reduction-of-3h-indoles
#14
Magnus Rueping
An enantioselective synthesis of spirocyclic indoline scaffolds was achieved by applying an asymmetric iridium catalyzed hydrogenation of 3H-indoles. Low catalyst loadings and mild reaction conditions provide a broad range of differently substituted products with excellent yields and enantioselectivities. The developed methodology allows an efficient synthesis of this important spirocyclic structural motif, which is present in numerous biologically active molecules and privileged structures in medicinal chemistry...
November 30, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27902868/the-tris-pentafluoroethyl-silanide-anion
#15
Nico Schwarze, Simon Steinhauer, Beate Neumann, Hans-Georg Stammler, Berthold Hoge
Tris(pentafluoroethyl)silane, which is conveniently accessible by the treatment of Si(C2 F5 )3 X (X=Cl, Br) with Bu3 SnH, was successfully employed for hydrosilylation reactions. In the presence of a palladium catalyst, hydrosilylation of phenylacetylene with Si(C2 F5 )3 H affords the product of an α-addition whereas the reaction of trimethylsilylacetylene with the silane leads to the β-trans product. Tris(pentafluoroethyl)silane can be deprotonated by sterically demanding bases such as lithium diisopropylamide at low temperatures to give the corresponding silanide ion...
November 30, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27902861/thioaldehydes-from-aldehyde-hydrogen-sulfide-interaction-under-organocatalysis
#16
Joseph S Francisco, Manoj Kumar
Thioaldehydes are an important class of sulfur compounds involved in atmospheric, synthetic organic and biological chemistry. Traditionally, they are believed to be formed by the nucleophilic attack of bisulfide anion on the carbonyl compounds. Herein we suggest a novel mechanism that does not require the formation of bisulfide anion, but rather involves an interaction between hydrogen sulfide and an aldehyde. Though the uncatalyzed or the water-catalyzed reactions involve high barriers, the formic acid-catalyzed reactions involve moderate barriers that should be accessible in planetary atmospheres...
November 30, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27902719/community-wide-distribution-of-a-catalytic-device-to-reduce-winter-ambient-fine-particulate-matter-from-residential-wood-combustion-a-field-study
#17
Olivia Johnston, Fay Johnston, John Todd, Grant Williamson
Residential wood combustion is the main source of elevated concentrations of fine particulate matter (PM2.5) during winter in many towns of Tasmania, Australia. A commercially available firebox catalyst in Australia has previously been shown to reduce visible smoke emissions and the manufacturer reports reductions in particle emissions generated from individual wood heaters in laboratory settings. This study aimed to evaluate the potential for community-wide distribution of the catalyst to improve the ambient winter air quality in the field...
2016: PloS One
https://www.readbyqxmd.com/read/27901528/au-i-ag-i-co-operative-catalysis-interception-of-ag-bound-carbocations-with-%C3%AE-gold-i-enals-in-the-imino-alkyne-cyclizations-with-n-allenamides
#18
Pradip N Bagle, Manoj V Mane, K Vanka, Dinesh R Shinde, Samir R Shaikh, Rajesh G Gonnade, Nitin T Patil
A co-operative Au(i)/Ag(i) catalyst system has been developed to utilize N-allenamides as nucleophilic enal equivalents for the interceptive capturing of incipient carbocations generated through π-acid-triggered imino-alkyne cyclization. The salient features include the in situ generation of silver-bound carbocations (from iminoalkynes), α-gold(i) enals (from N-allenamides) and union of these two species to form indolizines with the regeneration of Au and Ag catalysts.
November 30, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27901524/ternary-nicop-nanosheet-array-on-a-ti-mesh-a-high-performance-electrochemical-sensor-for-glucose-detection
#19
Zao Wang, Xiaoqin Cao, Danni Liu, Shuai Hao, Gu Du, Abdullah M Asiri, Xuping Sun
Electrode design is of significant importance in the construction of enhanced electrochemical sensing platforms, and nanoarrays are an attractive architecture in molecule detection with large specific surface area and easy access for target molecules. In this communication, we report on the development of a ternary NiCoP nanosheet array on a Ti mesh (NiCoP/Ti) as a non-noble metal efficient catalyst electrode for electro-oxidation of glucose in alkaline electrolytes. As an electrochemical sensor for glucose detection, NiCoP/Ti shows a fast response time of less than 3 s, a low detection limit of 0...
November 30, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27901318/selective-synthesis-of-cyclic-carbonate-by-salalen-aluminum-complexes-and-mechanistic-studies
#20
Mariachiara Cozzolino, Tomer Rosen, Israel Goldberg, Mina Mazzeo, Marina Lamberti
Salalen aluminum complexes were synthesized and used as catalysts in the reactions of CO2 with different epoxides. The reaction of cyclohexene oxide and CO2 was thoroughly investigated. In particular, the effect of the reaction conditions (nature and equivalents of the cocatalyst, CO2 pressure and temperature) and of the ligands (substituents on the ancillary ligand, nature of the labile ligand and nature of the nitrogen donor atoms) on the outcoming of this reaction were studied. The cycloaddition reaction of the CO2 with terminal epoxides, bearing different functional groups, was realized...
November 30, 2016: ChemSusChem
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