- Nitroarene and dye reduction with 2:1 Co/Al layered double hydroxide catalysts – Is gold still necessary?
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A 2:1 Co/Al layered double hydroxide (LDH) material was synthesized with Cl– anions intercalated and then anion exchanged with deprotonated methionine. This allowed further immobilization of Au nanoparticles. The catalytic performance of the set of three LDH materials for comparative benchmarking was assessed in the aqueous reduction of nitroaromatic compounds and of rhodamine dyes in the presence of NaBH4. All catalysts were found to be very active for the nitro-to-amine reduction. The same was observed for the dyes, where reduction rhodamine 6G was faster than that of rhodamine B, for all catalysts. While the Au-containing catalyst was apparently the one showing the best catalytic activity the LDH with Cl– was found to follow it closely in terms of catalytic performance. In addition, while the LDH catalyst with Au was prone to deactivation by amine products in recycling experiments, the LDH catalyst with Cl– was almost insensitive to that, which is a large advantage. These results showed that using a catalyst based on first-row metals for efficient processes is possible and addresses current sustainable and environmental concerns.
- Leandro, Sónia R.,Marques, Inês J.,Torres, Ruben S.,Fernandes, Tiago A.,Vaz, Pedro D.,Nunes, Carla D.
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supporting information
(2021/03/26)
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- Chemically Triggered Coalescence and Reactivity of Droplet Fibers
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We describe the role of functional polymer surfactants in the construction and triggered collapse of droplet-based fibers and the use of these macroscopic supracolloidal structures for reagent compartmentalization. Copolymer surfactants containing both zwitterionic and tertiary amine pendent groups were synthesized for stabilization of oil-in-water droplets, in which the self-adherent properties of the selected zwitterions impart interdroplet adherence, while the amine groups provide access to pH-triggered coalescence. Macroscopic fibers, obtained by droplet extrusion, were prepared with reagents embedded in spatially distinct components of the fibers. Upon acidification of the continuous aqueous phase, protonation of the polymer surfactants increases their hydrophilicity and causes rapid fiber disruption and collapse. Cross-linked versions of these supracolloidal fibers were stable upon acidification and appeared to direct interdroplet passage of encapsulants along the fiber length. Overall, these functional, responsive emulsions provide a strategy to impart on-demand chemical reactivity to soft materials structures that benefits from the interfacial chemistry of the system.
- Zhao, Jing,Pan, Zehao,Snyder, Deborah,Stone, Howard A.,Emrick, Todd
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supporting information
p. 5558 - 5564
(2021/05/04)
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- Reductive Coupling between C-N and C-O Electrophiles
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The cross-electrophile reaction is a promising strategy for C-C bond formation. Recent studies have focused mainly on reactions with organic halides. Here we report a coupling reaction between C-N and C-O electrophiles that demonstrates the possibility of constructing a C-C bond via C-N and C-O cleavage. Several reactions between benzyl/aryl ammonium salts and vinyl/aryl C-O electrophiles have been studied. Preliminary mechanistic studies revealed that the benzyl ammoniums were activated through a radical mechanism.
- He, Rong-De,Li, Chun-Ling,Pan, Qiu-Quan,Guo, Peng,Liu, Xue-Yuan,Shu, Xing-Zhong
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supporting information
p. 12481 - 12486
(2019/09/04)
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- Ionomer Cross-Linking Immobilization of Catalyst Nanoparticles for High Performance Alkaline Membrane Fuel Cells
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Polymer electrolyte membrane fuel cells can generate high power densities with low local emissions of pollutants. Optimal ionomer-Pt/C catalyst interactions in the electrodes enable the efficient generation and transport of ions and electrons required for high fuel cell performances. Critical durability issues involve agglomeration of the Pt/C nanoparticles (Pt/C NPs) and ionomer during discharging. Our novel approach involves ionomer cross-linking immobilization for the fabrication of durable catalyst layers for application in alkaline anion exchange membrane fuel cells (AEMFCs). Pt/C NP catalysts are employed alongside a poly(2,6-dimethyl-p-phenylene oxide)-(PPO)-based quaternary ammonium ionomer (containing terminal styrenic side-chain groups) to form porous catalyst layers. Following thermally initiated cross-linking of the terminal vinyl groups, an interconnected ionomer network forms conductive shells around the Pt/C aggregates. Ex situ catalytic activity and in situ durability tests demonstrate that this immobilization strategy inhibits Pt/C NP coalescence without sacrificing catalyst layer porosity. An initial demonstration of an H2/O2 AEMFC containing the new CBQPPO?Pt/C cathode shows that high peak power densities can be achieved (1.02 W cm-2 at 70 °C, raising to 1.37 W cm-2 with additional 0.1 MPa back-pressurization).
- Liang, Xian,Shehzad, Muhammad Aamir,Zhu, Yuan,Wang, Lianqin,Ge, Xiaolin,Zhang, Jianjun,Yang, Zhengjin,Wu, Liang,Varcoe, John Robert,Xu, Tongwen
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p. 7812 - 7820
(2019/10/11)
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- Modifier, modified and conjugated diene-based polymer and methods for preparing them
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The present invention relates to a modifier and a modified and conjugated diene-based polymer including a functional group derived therefrom, and more particularly, provides a modifier including a compound represented by Formula 1, a modified and conjugated diene-based polymer including a functional group derived from the modifier and a repeating unit derived from a conjugated diene-based monomer, and methods for preparing them. In Formula 1, the definition of each substituent is the same as defined in the description of the invention.
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Page/Page column 18
(2019/11/11)
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- Scope and Optimization of the Double Knorr Cyclization: Synthesis of Novel Symmetrical and Unsymmetrical Tricyclic 1,8-Diazaanthraquinones
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The Knorr cyclization of β-ketoanilides to form 2-quinolones in the presence of acid is well documented chemistry. Double Knorr cyclization is rare, with very few examples appearing in the literature to date. The double Knorr methodology can provide access to tricyclic 1,8-diazaanthraquinones, a scaffold seen in the diazaquinomycin family. The optimized synthesis of diazaquinomycin A and structural analogues thereof via double Knorr cyclization of di-β-ketoanilide precursor substrates is reported. The scope and generality of the double Knorr cyclization were investigated along with an optimization study. The double Knorr cyclization was found to be sensitive to steric bulk on precursor substrates. In addition, the presence of a 5-hydroxy group on the 1,3-di-β-ketoanilide facilitated the double Knorr cyclization, possibly due to its stabilizing effect on the carbocation intermediates formed during the reaction.
- Prior, Allan M.,Sun, Dianqing
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supporting information
p. 859 - 871
(2018/02/10)
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- Facile Fabrication of Nickel/Heazlewoodite@Carbon Nanosheets and their Superior Catalytic Performance of 4-Nitrophenol Reduction
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A facile molten salt method was utilized for the synthesis of carbon anchored nickel/heazlewoodite nanoparticles (Ni/Ni3S2@C nanosheets) with potassium humate as the carbon and sulfur source and NaCl as template. The morphology, particle size and crystallinity of the products were characterized by various techniques containing TEM, FE-SEM and XRD. Furthermore, the mesoporous Ni/Ni3S2@C own easy accessibility of active sites and high surface area (149.04 m2 g?1). Thus, the as-prepared Ni/Ni3S2@C exhibited prominent performance for catalytic reduction of 4-nitrophenol (4-NP). Catalytic reduction of other nitrophenols (NPs) were also tested which can prove that the catalyst own selectivity on reduction of NPs. For durability, the property of the catalyst does not decrease obviously after five cycles. More significant correlations concerning effect of activation parameters (Ea=37.21 kJ mol?1) on 4-NP reduction were scrutinized and discussed. Hence, we provide a facile method for fabrication of metal/metal sulfide@C which own better dispersity, small dimension and excellent catalytic performance for further studies.
- Wang, Xinyu,Lu, Jing,Zhao, Yunlong,Wang, Xiaopeng,Lin, Zhang,Liu, Xueming,Wu, Ronglan,Yang, Chao,Su, Xintai
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p. 4143 - 4153
(2018/09/06)
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- Carbon nitride supported palladium nanoparticles: An active system for the reduction of aromatic nitro-compounds
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Synthesis of carbon nitride supported highly dispersed ultrafine palladium nanoparticles has been reported for the reduction of aromatic nitro-compounds using hydrazine hydrate as a reducing agent. As a demonstration, the as-synthesized carbon nitride-palladium composite was shown to be a highly active and chemo-selective for the title reaction. Utilizing the optimized reaction conditions a set of aromatic nitro compounds have been converted to their corresponding amine derivatives with good to excellent yield ranging from 80% to 99%. The catalyst can be used for multiple times without affecting the catalytic performance and can also be stored for a long time at ambient condition maintaining the high catalytic efficiency.
- Nandi, Debkumar,Siwal, Samarjeet,Choudhary, Meenakshi,Mallick, Kaushik
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- Palladium Supported on Graphitic Carbon Nitride: An Efficient and Recyclable Heterogeneous Catalyst for Reduction of Nitroarenes and Suzuki Coupling Reaction
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In this study, a novel platelet-like nanocatalyst, Pd/g-C3N4 with easily approachable active sites, was developed. The mesoporous graphitic carbon nitride (g-C3N4) is a layered structure connected by planar amino groups, which can work as stabilizer and active support for noble metal nanoparticles. The palladium nanoparticles with an average particle size of 3.25 nm were evenly dispersed on the surface of g-C3N4 without aggregation. Detailed charaterizations reveal that there is no covalent-bond interaction between g-C3N4 and Pd NPs. The Pd/g-C3N4 catalyst showed excellent catalytic activity in the reduction of nitroarenes by NaBH4, and Suzuki coupling reaction of aryl halides with arylboronic acids under mild conditions. The reduction of 4-nitrophenol has a pseudo-first-order rate constant of 7.29 × 10-3 s-1, and an activity parameter of 1.37 s-1 mM-1, which is higher than those reported in the literature. Furthermore, the Suzuki coupling reactions processed smoothly with 97.0 % isolate yield in less than 30 min in water with PEG600 as the additive. The catalyst could be recycled for five times without significant loss of catalytic activity, which confirmed the good stability of the catalyst. Graphical Abstract: [Figure not available: see fulltext.]
- Zhao, Yukai,Tang, Ruiren,Huang, Rong
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p. 1961 - 1971
(2015/12/24)
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- 2-Aminobenzoxazole ligands of the hepatitis C virus internal ribosome entry site
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2-Aminobenzoxazoles have been synthesized as ligands for the hepatitis C virus (HCV) internal ribosome entry site (IRES) RNA. The compounds were designed to explore the less basic benzoxazole system as a replacement for the core scaffold in previously discovered benzimidazole viral translation inhibitors. Structure-activity relationships in the target binding of substituted benzoxazole ligands were investigated.
- Rynearson, Kevin D.,Charrette, Brian,Gabriel, Christopher,Moreno, Jesus,Boerneke, Mark A.,Dibrov, Sergey M.,Hermann, Thomas
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supporting information
p. 3521 - 3525
(2014/07/22)
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- A new family of thermo-responsive polymers based on poly[N-(4-vinylbenzyl)- N, N-dialkylamine]
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A new family of the thermo-responsive polymers based on poly[N-(4-vinylbenzyl)-N,N-dialkylamine] with the pendent amine group as well as the doubly thermo-responsive triblock copolymer were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. These polymers showed the lower critical solution temperature (LCST) and/or the upper critical solution temperature (UCST) in alcohol and in the alcohol/water mixture. The polymer molecular weight, the polymer concentration, the cosolvent/nonsolvent and the deuterated solvent affecting the LCST and/or UCST were investigated, and their great influence on the LCST/UCST was demonstrated. The origin of the phase transition of poly[N-(4-vinylbenzyl)-N,N-dialkylamine] at LCST upon heating was investigated and the possible reason was proposed. The doubly thermo-responsive triblock copolymer of PVMA53-b-PVEA 108-b-PVMA53 underwent phase transition at two LCST temperatures. The PVEA108 block underwent the initial phase transition at the first LCST of 32.5 C to form core-corona micelles, and then the subsequent phase transition of the PVMA53 block took place at the second LCST of 54.5 C to produce corona-collapsed micelles. The proposed polymers based on poly[N-(4-vinylbenzyl)-N,N-dialkylamine] are anticipated to broaden the thermo-responsive polymer range and will be useful in polymer science.
- Dan, Meihan,Su, Yang,Xiao, Xin,Li, Shentong,Zhang, Wangqing
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p. 3137 - 3146
(2013/06/04)
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- PYRIMIDINE DERIVATIVES
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The invention concerns benzamide compounds of Formula (I), or a pharmaceutically acceptable salt thereof, where R1, ring A, n, R3, and R4 are as defined in the description. The present invention also relates to processes for the preparation of such compounds, pharmaceutical compositions containing them and their use in the manufacture of a medicament for use as an antiproliferative agent in the prevention or treatment of tumours or other proliferative conditions which are sensitive to the inhibition of EphB4, and/or EphA2 and/or Src kinases.
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Page/Page column 89
(2011/04/14)
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- Synthesis of a series of monomeric styrene sulfobetaine precursors
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Procedures for the synthesis of five sulfobetaine monomers as styrene derivatives are given. The five molecules form a homologous row differing in the distance between the inner quaternary amine and the outer sulfonic acid from one methylene group to five methylene groups. Syntheses are achieved by a sequence of nucleophilic substitutions starting from commercially available precursors.
- Sonnenschein, Lukas,Seubert, Andreas
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scheme or table
p. 1101 - 1104
(2011/03/22)
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- Identification of a series of benzoxazoles as potent 5-HT6 ligands
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As part of our continuing efforts to identify therapeutics for CNS diseases such as schizophrenia and Alzheimer's disease (AD), we have been focused on the 5-HT6 receptor in order to identify potent and selective ligands as a potential treatment for cognitive dysfunction. Herein we report the identification of a novel series of benzoxazole derivatives as potent 5-HT6 ligands. The synthesis and detailed SAR of this class of compounds are reported. The compounds have been shown to be full antagonists in a cyclic AMP functional assay.
- Liu, Kevin G.,Lo, Jennifer R.,Comery, Thomas A.,Zhang, Guo Ming,Zhang, Jean Y.,Kowal, Dianne M.,Smith, Deborah L.,Di, Li,Kerns, Edward H.,Schechter, Lee E.,Robichaud, Albert J.
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scheme or table
p. 1115 - 1117
(2009/08/07)
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- Benzoxazole and benzothiazole derivatives as 5-hydroxytryptamine-6 ligands
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The present invention provides a compound of formula I and the use thereof for the treatment of a central nervous system disorder related to or affected by the 5-HT6 receptor.
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Page/Page column 14
(2008/06/13)
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