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https://www.readbyqxmd.com/read/29334621/taurine-as-a-green-bio-organic-catalyst-for-the-preparation-of-bio-active-barbituric-and-thiobarbituric-acid-derivatives-in-water-media
#1
Nader Daneshvar, Farhad Shirini, Mohaddeseh Safarpoor Nikoo Langarudi, Reyhaneh Karimi-Chayjani
Taurine, a β-amino acid that is abundantly available in the tissues of human and animals, is efficiently used as a green bio-organic catalyst in the preparation of some of the biologically active barbituric and thiobarbituric acid derivatives. In the presence of taurine, 5-Arylidene (thio) barbituric acid derivatives were prepared via Knovenagel reaction between aldehydes and (thio)barbituric acid. Using this reagent also pyrano[2,3-d]pyrimidinone(thione) derivatives were synthesized through a three-component reaction between aldehydes, (thio)barbituric and malononitrile...
December 21, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/29334396/towards-the-continuous-production-of-pt-based-heterogeneous-catalysts-using-microfluidic-systems
#2
Uson Laura, Manuel Arruebo, Victor Sebastian
The continuous production of Pt-based heterogeneous catalysts based on ultra-small (<2 nm) noble metal nanoparticles deposited on mesoporous ordered silica and their catalytic activity in VOC abatement are here reported. Microfluidic reactors can be used not only to enable the fast and controlled production of ultra-small Pt nanoparticles (NPs), but also alloyed NPs including PtPd, PtRu and PtRh can be formed in short residence times (between 60 s and 5 min). A novel continuous and homogeneous loading of these catalytic NPs on SBA-15 used as a mesoporous support is also here reported...
January 15, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29334395/probing-the-geometry-of-copper-and-silver-adatoms-on-magnetite-quantitative-experiment-versus-theory
#3
Matthias Meier, Zdeněk Jakub, Jan Balajka, Jan Hulva, Roland Bliem, Pardeep K Thakur, Tien-Lin Lee, Cesare Franchini, Michael Schmid, Ulrike Diebold, Francesco Allegretti, David A Duncan, Gareth S Parkinson
Accurately modelling the structure of a catalyst is a fundamental prerequisite for correctly predicting reaction pathways, but a lack of clear experimental benchmarks makes it difficult to determine the optimal theoretical approach. Here, we utilize the normal incidence X-ray standing wave (NIXSW) technique to precisely determine the three dimensional geometry of Ag1 and Cu1 adatoms on Fe3O4(001). Both adatoms occupy bulk-continuation cation sites, but with a markedly different height above the surface (0.43 ± 0...
January 15, 2018: Nanoscale
https://www.readbyqxmd.com/read/29334388/catalytic-de-hydrogenation-promoted-by-non-precious-metals-co-fe-and-mn-recent-advances-in-an-emerging-field
#4
REVIEW
Georgy A Filonenko, Robbert van Putten, Emiel J M Hensen, Evgeny A Pidko
Catalytic hydrogenation and dehydrogenation reactions form the core of the modern chemical industry. This vast class of reactions is found in any part of chemical synthesis starting from the milligram-scale exploratory organic chemistry to the multi-ton base chemicals production. Noble metal catalysis has long been the key driving force in enabling these transformations with carbonyl substrates and their nitrogen-containing counterparts. This review is aimed at introducing the reader to the remarkable progress made in the last three years in the development of base metal catalysts for hydrogenations and dehydrogenative transformations...
January 15, 2018: Chemical Society Reviews
https://www.readbyqxmd.com/read/29334175/efficient-catalytic-oxidation-of-5-hydroxymethylfurfural-to-2-5-furandicarboxylic-acid-by-magnetic-laccase-catalyst
#5
Ke-Feng Wang, Chun-Lei Liu, Kun-Yan Sui, Chen Guo, Chun-Zhao Liu
2,5-Furandicarboxylic acid (FDCA) is a biobased platform chemical for the production of polyesters. The magnetic laccase catalyst with TEMPO as the mediator has the remarkable capability of oxidizing HMF to 2,5-furandicarboxylic acid (FDCA). Under optimal reaction conditions, a quantitative yield (90.2%) of FDCA with complete HMF conversion was obtained after 96 h of reaction. More importantly, the magnetic laccase catalyst exhibited good recyclability and stability, maintaining 84.8% of its original activity following 6 reuse cycles...
January 15, 2018: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/29334145/colloidal-cobalt-phosphide-nanocrystals-as-trifunctional-electrocatalysts-for-overall-water-splitting-powered-by-a-zinc-air-battery
#6
Hui Li, Qi Li, Peng Wen, Trey B Williams, Shiba Adhikari, Chaochao Dun, Chang Lu, Dominique Itanze, Lin Jiang, David L Carroll, George L Donati, Pamela M Lundin, Yejun Qiu, Scott M Geyer
Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this work, highly monodisperse CoP and Co2 P nanocrystals (NCs) are synthesized using a robust solution-phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal-rich Co2 P NCs show higher OER performance owing to easier formation of plentiful Co2 P@COOH heterojunctions...
January 15, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29334116/interface-engineering-of-a-ceo2-cu3p-nanoarray-for-efficient-alkaline-hydrogen-evolution
#7
Zao Wang, Huitong Du, Zhiang Liu, Hui Wang, Abdullah M Asiri, Xuping Sun
It is of great importance to design and develop highly active electrocatalysts for the hydrogen evolution reaction (HER) under alkaline conditions. In this work, we report the development of a CeO2-Cu3P nanoarray supported on nickel foam (CeO2-Cu3P/NF) as an excellent HER catalyst with the demand of an overpotential of only 148 mV to deliver a geometrical catalytic current density of 20 mA cm-2 in 1.0 M KOH. Remarkably, this catalyst also shows strong long-term electrochemical durability for at least 100 h with nearly 100% Faradaic efficiency...
January 15, 2018: Nanoscale
https://www.readbyqxmd.com/read/29334102/ru-nanoparticles-dispersed-on-magnetic-yolk-shell-nanoarchitectures-with-fe3o4-core-and-sulfoacid-containing-periodic-mesoporous-organosilica-shell-as-bifunctional-catalysts-for-direct-conversion-of-cellulose-to-isosorbide
#8
Ying Yang, Wen Zhang, Feng Yang, Biao Zhou, Dehong Zeng, Na Zhang, Guoming Zhao, Shijie Hao, Xin Zhang
A green and sustainable approach for biorefining involves the development of bifunctional catalysts for the one-pot conversion of cellulosic biomass to isosorbide. This requires highly efficient, easily separated and versatile metal-acid catalysts for hydrolysis-hydrogenation-dehydration cascade reactions. Herein, we report a new type of metal-acid bifunctional catalyst by dispersing Ru nanoparticles (NPs) on magnetic yolk-shell nanoarchitectures comprising an Fe3O4 core and a sulfoacid (SO3H)-containing periodic mesoporous organosilica shell...
January 15, 2018: Nanoscale
https://www.readbyqxmd.com/read/29334091/selectivity-shift-from-paraffins-to-%C3%AE-olefins-in-low-temperature-fischer-tropsch-synthesis-in-the-presence-of-carboxylic-acids
#9
B Gu, A Y Khodakov, V V Ordomsky
A shift of selectivity to long chain α-olefins has been observed during Fischer-Tropsch synthesis over Co catalysts in the presence of carboxylic acids. The total selectivity to α-olefins of 39% was obtained in the presence of acids. The effect has been ascribed to intermediate formation of esters which hinder secondary olefin hydrogenation.
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29334089/asymmetric-4-2-annulations-to-construct-norcamphor-scaffolds-with-2-cyclopentenone-via-double-amine-thiol-catalysis
#10
Qian-Qian Yang, Wei Xiao, Wei Du, Qin Ouyang, Ying-Chun Chen
An efficient double catalytic system, combining chiral amine and 2-mercaptobenzoic acid, is applied for α',β-regioselective [4+2] annulations of 2-cyclopentenone with a diversity of activated alkenes, constructing multifunctional chiral bicycle[2,2,1]heptane scaffolds in good to excellent yields and enantioselectivities. In comparison with the traditional cross-dienamine species between 2-cyclopentenone and chiral amine, the interrupted enamine intermediate containing a covalently linked thiol catalyst shows significantly improved reactivity...
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29334086/n-doped-graphene-supported-pdcu-nanoalloy-as-efficient-catalyst-for-reducing-cr-vi-by-formic-acid
#11
Shuangzhi Li, Lijun Liu, Qing Zhao, Chiyang He, Weikai Liu
Reducing Cr(vi) to Cr(iii) with formic acid is desirable for environmental protection, but the sluggish kinetics limits its practical application, which currently motivates the intensive study of efficient catalysts for this redox reaction. Here bimetallic PdCu nanoalloy (∼5 nm in size) supported by N-doped graphene was synthesized through a one-pot hydrothermal process. The catalytic activity of PdCu nanoalloy highly depends on the Pd/Cu atomic ratio and N-doped graphene support. The obtained Pd6Cu4/NG shows superior catalysis towards the Cr(vi) reduction by formic acid with a high kinetic constant (kn = 23...
January 15, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29333927/comprehensive-characterization-of-hydrothermal-liquefaction-products-obtained-from-woody-biomass-under-various-alkali-catalyst-concentrations
#12
Hyewon Hwang, Jae Hoon Lee, In Gyu Choi, Joon Weon Choi
Hydrothermal liquefaction (HTL) of lignocellulosic biomass has been widely investigated for the production of renewable and alternative bio-crude oil. In this study, catalytic hydrothermal processing of two biomasses (larch and Mongolian oak) was performed using different K2CO3 concentrations (0, 0.1, 0.5, 1.0wt% of solvent) to improve fuel yield and properties. HTL oil, hydrochar, water soluble fraction (WSF) and gas were characterized and carbon balance was investigated. As a result, the maximum yield of HTL oil, 27...
January 15, 2018: Environmental Technology
https://www.readbyqxmd.com/read/29333857/active-site-revealed-for-water-oxidation-on-electrochemically-induced-%C3%AE-mno2-role-of-spinel-to-layer-phase-transition
#13
Yefei Li, Zhi-Pan Liu
Seeking for active MnOx material as artificial water splitting catalyst has been a long history since the discovery of PSII system in Nature. To date, the highest activity MnOx catalyst reported for oxygen evolution reaction (OER) is however not common MnO2 polymorphs (α-, β-, δ-MnO2), but nascent δ-MnO2 layer produced in situ from spinel under electrochemical conditions with unknown active site structure. Here with the stochastic surface walking (SSW) pathway sampling method, we for the first time resolve the atomic-level mechanism of spinel-to-layer Mn3O4 solid phase transition in aqueous electrolyte...
January 15, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29333855/carbon-and-binder-free-core-shell-nanowire-arrays-for-efficient-ethanol-electro-oxidation-in-alkaline-medium
#14
Fen Guo, Yiju Li, Baoan Fan, Yi Liu, Lilin Lu, Yang Lei
To achieve high electrochemical surface area (ECSA) and avoid carbon support and binder in the anode catalyst of direct ethanol fuel cell, herein, we design freestanding core-shell nickel@palladium-nickel nanowire arrays (Ni@Pd-Ni NAs) without carbon support and binder for high-efficiency ethanol electro-oxidation. Bare Ni nanowire arrays (Ni NAs) are first prepared using the facile template-assistantelectrodeposition method. Subsequently, the Ni@Pd-Ni NAs are formed using one-step solution-based alloying reaction...
January 15, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29333739/nickel-based-photo-electrocatalysts-for-hydrogen-production
#15
REVIEW
Lvlv Ji, Cuncai Lv, Zuofeng Chen, Zhipeng Huang, Chi Zhang
Hydrogen is considered a promising energy carrier for replacing traditional fossil fuels. Electrochemical or solar-driven water splitting is a green and sustainable method of producing hydrogen. To lower the overpotential and minimize energy costs, numerous reports have focused on developing noble-metal-free catalysts for hydrogen production, with special attention paid to nickel-based materials. Herein, the current state of research on the use of Ni-based materials as electrocatalysts, cocatalysts, and photoactive materials in hydrogen production is reviewed...
January 15, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29333666/stable-high-index-faceted-pt-skin-on-zigzag-like-ptfe-nanowires-enhances-oxygen-reduction-catalysis
#16
Mingchuan Luo, Yingjun Sun, Xu Zhang, Yingnan Qin, Mingqiang Li, Yingjie Li, Chunji Li, Yong Yang, Lei Wang, Peng Gao, Gang Lu, Shaojun Guo
Selectively exposing active surfaces and judiciously tuning the near-surface composition of electrode materials represent two prominent means of promoting electrocatalytic performance. Here, a new class of Pt3 Fe zigzag-like nanowires (Pt-skin Pt3 Fe z-NWs) with stable high-index facets (HIFs) and nanosegregated Pt-skin structure is reported, which are capable of substantially boosting electrocatalysis in fuel cells. These unique structural features endow the Pt-skin Pt3 Fe z-NWs with a mass activity of 2.11 A mg-1 and a specifc activity of 4...
January 15, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29333655/preparation-of-high-percentage-1t-phase-transition-metal-dichalcogenide-nanodots-for-electrochemical-hydrogen-evolution
#17
Chaoliang Tan, Zhimin Luo, Apoorva Chaturvedi, Yongqing Cai, Yonghua Du, Yue Gong, Ying Huang, Zhuangchai Lai, Xiao Zhang, Lirong Zheng, Xiaoying Qi, Min Hao Goh, Jie Wang, Shikui Han, Xue-Jun Wu, Lin Gu, Christian Kloc, Hua Zhang
Nanostructured transition metal dichalcogenides (TMDs) are proven to be efficient and robust earth-abundant electrocatalysts to potentially replace precious platinum-based catalysts for the hydrogen evolution reaction (HER). However, the catalytic efficiency of reported TMD catalysts is still limited by their low-density active sites, low conductivity, and/or uncleaned surface. Herein, a general and facile method is reported for high-yield, large-scale production of water-dispersed, ultrasmall-sized, high-percentage 1T-phase, single-layer TMD nanodots with high-density active edge sites and clean surface, including MoS2 , WS2 , MoSe2 , Mo0...
January 15, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29333558/selective-hydrogenation-of-nitroarenes-using-an-electrogenerated-polyoxometalate-redox-mediator
#18
Lewis MacDonald, Benjamin Rausch, Mark D Symes, Leroy Cronin
The 2-electron reduced form of the polyoxometalate silicotungstic acid (H4[SiW12O4]) is shown to be an effective and selective hydrogenation agent for a range of nitroarenes without the need for any co-catalyst. The ease of generation of the active species and its recyclability suggest that a new approach to this important class of chemical conversions is possible.
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29333548/efficient-generation-of-an-oxidopyrylium-ylide-using-a-pd-catalyst-and-its-5-2-cycloadditions-with-several-dipolarophiles
#19
Hiroyuki Suga, Taichi Iwai, Masahiro Shimizu, Kie Takahashi, Yasunori Toda
An efficient method for the generation of an oxidopyrylium ylide from 6-acetoxy-6-acetoxymethyl-2H-pyran-3(6H)-one using a Pd catalyst and [5+2] cycloadditions of the resulting ylide are described. Among substituted styrene derivatives as dipolarophiles, electron-rich styrenes showed higher yield (up to 80%). The [5+2] cycloaddition reactions can also be applied to exo-methylene cyclic compounds, and an improved method for the synthesis of polygalolide intermediate has been demonstrated.
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29333544/formal-total-synthesis-of-salvianolic-acid-n
#20
Kong Wu, Zhong Pao Xie, Dong-Mei Cui, Chen Zhang
An efficient synthetic pathway for the total synthesis of salvianolic acid N has been reported. The key reaction steps, the Wittig reaction for Z-stereoselectivity and an intramolecular cyclization for a seven membered ring skeleton, have been optimized to improve the synthetic feasibility and provide the best conditions in terms of yield. Moreover, a notable reaction is the reaction of the deprotected allylic group with Pd catalyst. An improved overall yield of 11% has been achieved for salvianolic acid N starting from 3,4-dimethoxybenzaldehyde in 11 steps...
January 15, 2018: Organic & Biomolecular Chemistry
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