- Substitution of OH with NH2 in calix[4]arenes: An approach to the synthesis of aminocalixarenes
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From p-t-butylcalix[4]arene bis(diethylphosphate) ester (1), monodehydroxymonoamino-p-t-butylcalix[4]arene (3) and diamino-p-t-butyl-calix[4]arene (4) were synthesized in liquid ammonia-co-solvent in the presence of KNH2. This is the first successful example for the substitution of the OH group with the NH2 group.
- Ohseto,Murakami,Araki,Shinkai
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Read Online
- Structural and Reactivity Comparisons of JosiPhos CyPF-Cy and a Simplified Variant ("CyPBn-Cy") in Nickel-Catalyzed C(sp2)-N Cross-Couplings
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The synthesis and characterization of the new complexes (CyPBn-Cy)NiCl2 and (CyPBn-Cy)Ni(o-tol)Cl are reported (CyPBn-Cy = o-di(cyclohexyl)phosphino-benzyl-di(cyclohexyl)phosphine), along with a head-to-head structural and reactivity comparison of (L)Ni(o-tol)Cl precatalyst complexes (L = JosiPhos CyPF-Cy and CyPBn-Cy) in the Ni-catalyzed cross-couplings of (hetero)aryl chlorides or phenol-derived electrophiles with ammonia or furfurylamine. The structures of these precatalysts were found not to differ significantly (e.g., coordination geometry and % buried volume), and these similarities were, generally speaking, reflected in the observed catalytic behavior of these precatalysts, with notable exceptions including reactions involving the hindered electrophile 2-chloro-m-xylene, where (CyPBn-Cy)Ni(o-tol)Cl proved superior; the N-arylation of furfurylamine by use of 1-(N,N-diethylcarbamoyl)-naphthalene, where CyPF-Cy proved to be the preferred ligand; and monoarylation (CyPBn-Cy) versus diarylation (CyPF-Cy) selectivity in the cross-coupling of furfurylamine with 2-chloro-6-methoxypyridine. In studying the time-course of the cross-coupling of furfurylamine and 1-chloronaphthalene, significantly faster conversion to product and higher overall yield were noted when using CyPBn-Cy. These results confirm that CyPBn-Cy can be viewed as being competitive with, and complementary to, the well-established JosiPhos ligand CyPF-Cy in this class of Ni-catalyzed cross-couplings.
- Bodé, Nicholas E.,Ferguson, Michael J.,Stradiotto, Mark,Tassone, Joseph P.
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p. 2915 - 2922
(2021/08/27)
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- Rhodium-terpyridine Catalyzed Transfer Hydrogenation of Aromatic Nitro Compounds in Water
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A rhodium terpyridine complex catalyzed transfer hydrogenation of nitroarenes to anilines with i-PrOH as hydrogen source and water as solvent has been developed. The catalytic system can work at a substrate/catalyst (S/C) ratio of 2000, with a turnover frequency (TOF) up to 3360 h?1, which represents one of the most active catalytic transfer hydrogenation systems for nitroarene reduction. The catalytic system is operationally simple and the protocol could be scaled up to 20 gram scale. The water-soluble catalyst bearing a carboxyl group could be recycled 15 times without significant loss of activity.
- Liu, Yuxuan,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Wang, Chao,Li, Changzhi
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supporting information
p. 1725 - 1729
(2021/06/01)
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- Chemoselective Hydrogenation of Nitroarenes Using an Air-Stable Base-Metal Catalyst
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The reduction of nitroarenes to anilines as well as azobenzenes to hydrazobenzenes using a single base-metal catalyst is reported. The hydrogenation reactions are performed with an air-and moisture-stable manganese catalyst and proceed under relatively mild reaction conditions. The transformation tolerates a broad range of functional groups, affording aniline derivatives and hydrazobenzenes in high yields. Mechanistic studies suggest that the reaction proceeds via a bifunctional activation involving metal-ligand cooperative catalysis.
- Zubar, Viktoriia,Dewanji, Abhishek,Rueping, Magnus
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supporting information
p. 2742 - 2747
(2021/05/05)
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- Hydroboration reduction reaction of aromatic nitro compounds without transition metal catalysis
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The invention relates to a hydroboration reduction reaction of aromatic nitro compounds without transition metal catalysis. According to the method, triethyl boron and potassium tert-butoxide are used as catalysts for the first time, and an aromatic nitro compound and pinacol borane which is low in price and easy to obtain can be conveniently catalyzed to be subjected to a hydroboration reduction reaction under mild conditions to prepare aromatic amine products. Compared with a traditional method, the method generally has the advantages that the catalyst is cheap and easy to obtain, operation is convenient, and reaction is safe. The selective hydroboration reduction reaction of the non-transition metal reagent catalyzed aromatic nitro compound and pinacol borane is realized for the first time, and a practical new reaction strategy is provided for laboratory preparation or industrial production of aromatic amine products.
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Paragraph 0006; 0057-0060
(2021/07/31)
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- Pd nanoparticles/graphene quantum dot supported on chitosan as a new catalyst for the reduction of nitroarenes to arylamines
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A new heterogeneous catalyst was obtained by growing graphene quantum dots on chitosan and subsequent immobilization of Pd nanoparticles. The catalyst after characterization was used in the reduction of nitroarenes to the corresponding amines by NaBH4 as a weak reducing agent of nitro compounds. The catalyst exhibited excellent catalytic activity and selectivity under mild reaction conditions in water as a green solvent during 1?h. Additionally, the catalyst can be reused for five consecutive runs without any significant decrease in its activity and selectivity.
- Kalanpour, Nastaran,Nejati, Saeid,Keshipour, Sajjad
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p. 1243 - 1250
(2020/10/29)
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- Biogenic Synthesis of Gold Nanoparticles on a Green Support as a Reusable Catalyst for the Hydrogenation of Nitroarene and Quinoline
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Direct attachment of gold nanoparticles to a green support without the use of an external reducing agent and using it for removing toxic pollutants from wastewater, i. e., reduction of nitroarene to amine, are described. A novel approach involving the reduction of gold by the jute plant (Corchorus genus) stem-based (JPS) support itself to form nanoparticles (AuNPs) to be used as a catalytic system (‘dip-catalyst’) and its catalytic activity for the hydrogenation of series of nitroarenes in aqueous media are presented. AuNPs/JPS catalyst was characterized using SEM, UV-Vis, FTIR, TEM, XPS, and ICP-OES. Confined area elemental mapping exhibits uniform and homogeneous distribution of AuNPs on the support surface. TEM shows multi-faceted AuNPs in the range of 20–30 nm. The reactivity of AuNPs/JPS for the transfer hydrogenation of nitroarene as well as hydrogenation of quinoline under molecular H2 pressure was evaluated. Sodium borohydride, when used as the hydrogen source, demonstrates a high catalytic efficiency in the transfer hydrogenation reduction of 4-nitrophenol (4-NP). Quinoline is quantitatively and chemoselectively hydrogenated to 1,2,3,4-tetrahydroquinoline (py-THQ) using molecular hydrogen. Reusability studies show that AuNPs are stable on the support surface and their selectivity is not affected.
- Adeyeye Nafiu, Sodiq,Aziz, Abdul,Shaheen Shah, Syed,Shaikh, M. Nasiruzzaman
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p. 1956 - 1966
(2021/06/18)
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- Sustainable and recyclable palladium nanoparticles–catalyzed reduction of nitroaromatics in water/glycerol at room temperature
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Palladium nanoparticles with unique catalytic activity and high stability are synthesized. These nanoparticles exhibit excellent catalytic reduction activity for nitroaromatics in green solvents in the presence of H2 at ambient pressure and temperature. The prominent advantages of this nanotechnology include low consumption of catalyst, excellent chemoselectivity, high reusability of the catalyst, and environmentally green solvents.
- Chen, Jin,Dai, Bencai,Liu, Changchun,Shen, Zhihao,Zhao, Yongde,Zhou, Yang
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p. 540 - 544
(2020/07/14)
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- Single-atom Fe-N4site for the hydrogenation of nitrobenzene: theoretical and experimental studies
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The hydrogenation of nitrobenzene to aniline is an important process in the industry of fine chemicals, but developing inexpensive catalysts with expected activity and selectivity still remains a challenge. By using density functional theory calculations, we demonstrated that the isolated Fe atom not only can weaken the adsorption of reactants and reaction intermediates as compared to Fe nanoparticles, but also remarkably decrease the reaction barrier for the hydrogenation of nitrobenzene to aniline. Thus, the Fe single-atom (Fe SA) catalyst is considered as an ideal catalyst for this reaction. This theoretical prediction has been subsequently confirmed by experimental results obtained for the Fe SAs loaded on N-doped hollow carbon spheres (Fe SAs/NHCSs) which achieved a conversion of 99% with a selectivity of 99% for the hydrogenation of nitrobenzene. The results significantly outperformed the Fe nanoparticles for this reaction. This work provides theoretical insight for the rational design of new catalytic systems with excellent catalytic properties.
- Dong, Panpan,He, Rong,Liu, Yan,Lu, Ning,Mao, Junjie,Wu, Konglin,Zhang, Wenzhuang,Zheng, Yamin
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supporting information
p. 7995 - 8001
(2021/06/21)
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- Efficient hydrogenation catalyst designing via preferential adsorption sites construction towards active copper
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Based on the experimental and DFT calculation results, here for the first time we built preferential adsorption sites for nitroarenes by modification of the supported Cu catalysts surface with 1,10-phenathroline (1,10-phen), by which the yield of aniline via reduction of nitroarene is enhanced three times. Moreover, a macromolecular layer was in-situ generated on supported Cu catalysts to form a stable macromolecule modified supported Cu catalyst, i.e., CuAlOx-M. By applying the CuAlOx-M, a wide variety of nitroarene substrates react smoothly to afford the desired products in up to > 99% yield with > 99% selectivity. The method tolerates a variety of functional groups, including halides, ketone, amide, and C = C bond moieties. The excellent catalytic performance of the CuAlOx-M can be attributed to that the 1,10-phen modification benefits the preferential adsorption of nitrobenzene and slightly weakens adsorption of aniline on the supported nano-Cu surface.
- Dai, Xingchao,He, Dongcheng,Li, Teng,Shi, Feng,Wang, Hongli,Wang, Tao,Wang, Xinzhi
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p. 397 - 406
(2021/07/21)
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- Minimization of Back-Electron Transfer Enables the Elusive sp3 C?H Functionalization of Secondary Anilines
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Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N-Dialkyl-derivatives enable radical generation α to the N-atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back-electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α-anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C?H functionalization.
- Zhao, Huaibo,Leonori, Daniele
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supporting information
p. 7669 - 7674
(2021/03/08)
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- Synthesis of Substituted Anilines from Cyclohexanones Using Pd/C-Ethylene System and Its Application to Indole Synthesis
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The synthesis of anilines and indoles from cyclohexanones using a Pd/C-ethylene system is reported. A simple combination of NH4OAc and K2CO3 under nonaerobic conditions was found to be the most suitable to perform this reaction. Hydrogen transfer between cyclohexanone and ethylene generates the desired products. The reaction tolerates a variety of substitutions on the starting cyclohexanones.
- Maeda, Katsumi,Matsubara, Ryosuke,Hayashi, Masahiko
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supporting information
p. 1530 - 1534
(2021/03/08)
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- Selective primary aniline synthesis through supported Pd-catalyzed acceptorless dehydrogenative aromatization by utilizing hydrazine
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By utilizing hydrazine (N2H4) as the nitrogen source in the presence of a hydroxyapatite-supported Pd nanoparticle catalyst (Pd/HAP), various primary anilines can be selectively synthesized from cyclohexanonesviaacceptorless dehydrogenative aromatization. The strong nucleophilicity of N2H4and the stability of the hydrazone intermediates can effectively suppress the formation of the undesired secondary aniline byproducts.
- Lin, Wei-Chen,Yatabe, Takafumi,Yamaguchi, Kazuya
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supporting information
p. 6530 - 6533
(2021/07/07)
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- C-H Amination of Arenes with Hydroxylamine
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This Letter describes the development of a TiIII-mediated reaction for the C-H amination of arenes with hydroxylamine. This reaction is applied to a variety of electron-rich (hetero)arene substrates, including a series of natural products and pharmaceuticals. It offers the advantages of mild conditions (room temperature), fast reaction rates (30 min), compatibility with ambient moisture and air, scalability, and the use of inexpensive commercial reagents.
- See, Yi Yang,Sanford, Melanie S.
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supporting information
p. 2931 - 2934
(2020/04/09)
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- Method for reducing aromatic nitro compounds into aromatic amine compounds
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The invention discloses a method for reducing aromatic nitro compounds into aromatic amine compounds. The aromatic nitro compounds are reacted at a temperature of 110-130 DEG C in an inert or air atmosphere under the action of a rhodium catalyst by using water as a solvent, isopropanol as a hydrogen source and potassium phosphate or sodium carbonate as an alkali to obtain the aromatic amine compounds. The method has the advantages of simplicity in operation, greenness, environmental friendliness, reduction of environmental pollution, high reaction yield, amplified gram-scale preparation of theamine compounds, high catalyst activity, recyclability and low industrial production cost.
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Paragraph 0030-0031; 0036-0037
(2020/03/25)
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- Copper(II) complex with oxazoline ligand: Synthesis, structures and catalytic activity for nitro compounds reduction
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The Cu(II) complexes bearing bisoxazolines, tridentate pincer pybox and terpyridine ligands have been synthesized and fully characterized. The molecular structures of copper complexes 1a and 1c were confirmed by single-crystal X-ray diffraction methods. These copper complexes highly catalyzed nitro compounds reduction to aniline and its derivatives in the presence of NaBH4 reducing agent in water solvent. The complex 1e was an efficient catalyst toward nitro compounds reduction with wide functional group substrate scope and aliphatic nitro compounds.
- Du, Jun,Gao, Li-Li,Jia, Wei-Guo,Li, Mei,Zhi, Xue-Ting
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- Commercially Available CuO Catalyzed Hydrogenation of Nitroarenes Using Ammonia Borane as a Hydrogen Source
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Tandem ammonia borane dehydrogenation and nitroarenes hydrogenation has been reported as a novel strategy for the preparation of aromatic amines. However, the practical application of this strategy is subjected to the high-cost and tedious preparation of supported noble metal nanocatalysts. The commercially available CuO powder is herein demonstrated to be a robust catalyst for hydrogenation of nitroarenes using ammonia borane as a hydrogen source under mild conditions. Numerous amines (even sterically hindered, halogenated, and diamines) could be obtained through this method. This monometallic catalyst is characteristic of support-free, excellent chemoselectivity, low-cost, and high recyclability, which will favor its future utilization in preparative reduction chemistry. Mechanistic studies are also carried out to clarify that diazene and azoxybenzene are key intermediates of this heterogeneous reduction.
- Du, Jialei,Chen, Jie,Xia, Hehuan,Zhao, Yiwei,Wang, Fang,Liu, Hong,Zhou, Weijia,Wang, Bin
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p. 2426 - 2430
(2020/03/30)
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- Method for preparing lidocaine
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The invention discloses a method for preparing lidocaine. The method comprises the following steps of: (1) by using 2, 6-dimethylnitrobenzene as a raw material, Pd/C as a catalyst and methanol as a solvent, carrying out reduction reaction with hydrogen at normal temperature and normal pressure to obtain an intermediate 2, 6-dimethylaniline; (2) reacting the obtained intermediate 2, 6-dimethylaniline with chloroacetyl chloride in the presence of potassium carbonate, and taking dichloromethane as a solvent to prepare an intermediate chloroacetyl-2, 6-dimethylaniline; and (3) reacting the obtained intermediate chloroacetyl-2, 6-dimethylaniline with diethylamine, taking normal hexane as a solvent, performing refluxing until the reaction is complete, performing washing with water and cooling toobtain lidocaine. The method disclosed by the invention is simple and convenient in technological process, few in operation links and relatively high in lidocaine yield, and the prepared lidocaine isgood in purity which reaches 99.5% or above, so that the method has a good industrial application prospect.
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Paragraph 0031-0033; 0038-0040; 0045-0047
(2020/04/17)
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- The immobilized Cu nanoparticles on magnetic montmorillonite (MMT?Fe3O4?Cu): As an efficient and reusable nanocatalyst for reduction and reductive-acetylation of nitroarenes with NaBH4
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In this study, the immobilization of copper nanoparticles on superparamagnetic montmorillonite, MMT?Fe3O4?Cu, was studied. Magnetically nanoparticles (MNPs) of iron oxide (Fe3O4) were primarily prepared by a chemical co-precipitation method. Next, the prepared Fe3O4 MNPs were intercalated within the interlamellar spaces and external surface of sodium-exchanged montmorillonite. Finally, Cu NPs were immobilized on magnetic montmorillonite by a simply mixing of an aqueous solution of CuCl2·2H2O with MMT?Fe3O4 followed by the reduction with NaBH4. Characterization of MMT?Fe3O4 clay system represented that through the immobilization of Fe3O4 MNPs, disordered-layers structure of MMT was easily reorganized to an ordered-layers arrangement. The synthesized composite systems were characterized using FT-IR, SEM, EDX, XRD, VSM, BET and ICP-OES analyses. SEM analysis exhibited that dispersion of Cu NPs, with the size distribution of 15–25 nm, on the surface of magnetic clay was taken place perfectly. BET surface analysis indicated that after the immobilization of Fe3O4 and Cu species, the surface area and total pore volume of MMT?Fe3O4?Cu system was decreased. Next, the Cu-clay nanocomposite system showed a perfect catalytic activity towards reduction of nitroarenes to anilines as well as reductive-acetylation of nitroarenes to acetanilides using NaBH4 and Ac2O in water as a green and economic solvent. The copper magnetic clay catalyst can be easily separated from the reaction mixture by an external magnetic field and reused for six consecutive cycles without the significant loss of its catalytic activity.
- Zeynizadeh, Behzad,Rahmani, Soleiman,Tizhoush, Hengameh
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- Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
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We report a catalytic tandem reduction of nitroarenes by sodium borohydride (NaBH4) in aqueous solution under ambient conditions, which can selectively produce five categories of nitrogen-containing compounds: anilines, N-aryl hydroxylamines, azoxy-, azo- and hydrazo-compounds. The catalyst is in situ-generated ultrasmall palladium nanoclusters (Pd NCs, diameter of 1.3 ± 0.3 nm) from the reduction of Pd(OAc)2 by NaBH4. These highly active Pd NCs are stabilized by surface-coordinated nitroarenes, which inhibit the further growth and aggregation of Pd NCs. By controlling the concentration of Pd(OAc)2 (0.1-0.5 mol% of nitroarene) and NaBH4, the water/ethanol solvent ratio and the tandem reaction sequence, each of the five categories of N-containing compounds can be obtained with excellent yields (up to 98%) in less than 30 min at room temperature. This tunable catalytic tandem reaction works efficiently with a broad range of nitroarene substrates and offers a green and sustainable method for the rapid and large-scale production of valuable N-containing chemicals.
- Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
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supporting information
p. 1301 - 1307
(2020/03/11)
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- Half-sandwich ruthenium complexes with Schiff base ligands bearing a hydroxyl group: Preparation, characterization and catalytic activities
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Three half-sandwich ruthenium(II) complexes with hydroxyl group functionalized Schiff-base ligands [Ru(p-cymene)LCl] (2a-2c) have been synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry and infrared spectrometry. The molecular structure of ruthenium complex 2c was confirmed by single-crystal X-ray diffraction methods. Furthermore, these half-sandwich ruthenium complexes were found to exhibit high catalytic activity for nitro compounds reduction using NaBH4 reducing agent in the presence of cetyltrimethylammonium bromide (CTAB) in water at room temperature.
- Jia, Wei-Guo,Wang, Zhi-Bao,Zhi, Xue-Ting
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- The immobilized copper species on nickel ferrite (NiFe2O4@Cu): a magnetically reusable nanocatalyst for one-pot and quick reductive acetylation of nitroarenes to N-arylacetamides
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In this study, a green protocol for synthesis of N-arylacetamides was introduced. Magnetically, nanoparticles of the immobilized copper species on nickel ferrite, NiFe2O4@Cu, were synthesized and then characterized using SEM, EDX, XRD, VSM, ICP-OES, BET and XPS analyses. The XPS analysis approved that the immobilized copper species on NiFe2O4 only contain Cu(0) and its oxide form as CuO. The prepared nanocomposite system represented a perfect catalytic activity toward one-pot and quick reductive acetylation of various nitroarenes to the corresponding N-arylacetamides. All reactions were carried out in a mixture of H2O–EtOH (1.5–0.5) within 2–10?min using the combination system of NaBH4 and Ac2O in a one-pot approach and via a two-step procedure. The utilized Cu nanocomposite was magnetically separated from the reaction mixture and reused for 5 consecutive cycles without the significant loss of its catalytic activity.
- Zeynizadeh, Behzad,Shokri, Zahra,Mohammadzadeh, Iman
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p. 859 - 870
(2019/12/24)
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- Shape-dependent reactivity and chemoselectivity of nanogold towards nitrophenol reduction in water
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Although the catalytic activity of nano-gold surfaces for the reduction of nitro compounds has been known, the effect of their shape has been rarely evaluated. Here, the synthesis, characterization, and application of both gold nanoworms (GNW) and gold nanospheres (GNS) are described. Both GNW and GNS were characterized using SEM, TEM, UV–Vis, FTIR, and XPS spectroscopy. The catalytic efficiency of GNW with an average dimensions of 2 × 250 nm (D × L) towards the hydrogenation of nitrophenol, a pollutant present in industrial wastewater, is higher (TOF 3675 h?1) than that of spherical GNS (10 ± 1 nm), for which TOF is 1838 h?1 in water using NaBH4 as the reductant. The selectivity of 4-aminophenol is 100% for both GNS and GNW.
- Aziz, Md Abdul,Nafiu, Sodiq Adeyeye,Shaikh, M. Nasiruzzaman
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- Synthesis method of aniline compound
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The invention provides a synthesis method of an aniline compound. The synthesis comprises the following steps: taking a carbon-coated nickel nano composite material containing alkali metals as a catalyst, and catalyzing a hydrogenation reduction reaction of a nitrobenzene compound in a hydrogen atmosphere, wherein the nano composite material contains a core-shell structure with a shell layer and an inner core, the shell layer is a graphitized carbon layer containing alkali metal, nitrogen and oxygen, and the inner core is nickel nano particles. According to the method, the nano composite material is used as a catalyst; a carbon material and the nickel nano particles generate a synergistic effect and a good catalytic effect, the alkali metals of the shell layer further synergistically improve the catalytic performance of the nano composite material, and the catalyst is used for hydrogenation reduction of nitrobenzene compounds to synthesize aniline compounds, and has excellent activity,selectivity and safety.
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Paragraph 0139-0141
(2020/08/09)
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- Synthesis method of aniline compound
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The invention provides a synthesis method of an aniline compound. The synthesis method comprises the following steps: taking a carbon-coated nickel nano composite material containing alkaline-earth metals as a catalyst, and catalyzing a hydrogenation reduction reaction of a nitrobenzene compound in a hydrogen atmosphere; wherein the nano composite material contains a core-shell structure with a shell layer and an inner core, the shell layer is a graphitized carbon layer containing alkaline-earth metals, nitrogen and oxygen, and the inner core is nickel nano particles. According to the method,the nano composite material is used as a catalyst; the carbon material and the nickel nano particles generate a synergistic effect and a good catalytic effect, the alkaline-earth metals of the shell layer further synergistically improve the catalytic performance of the nano composite material, and the catalyst is used for hydrogenation reduction of nitrobenzene compounds to synthesize aniline compounds, and has excellent activity, selectivity and safety.
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Paragraph 0138-0140
(2020/08/09)
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- IRON OXIDE SUPPORTED RHODIUM CATALYST FOR NITROARENE REDUCTION
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A supported catalyst having rhodium particles with an average diameter of less than 1 nm disposed on a support material containing magnetic iron oxide (e.g. Fe3O4). A method of producing the supported catalyst and a process of reducing nitroarenes to corresponding aromatic amines employing the supported catalyst with a high product yield are also described. The supported catalyst may be recovered with ease using an external magnet and reused.
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Paragraph 0133; 0144
(2020/12/29)
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- Superhydrophobic nickel/carbon core-shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles
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In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step. Nevertheless, how to effectively reduce the possible effects of water on the catalyst by removal of the by-product water, and to further introduce water as the solvent based on green chemistry are still challenges. Since the structures and properties of carbon nanocomposites are easily modified by controllable construction, a one step pyrolysis process is used for controllable construction of micro/nano hierarchical carbon nanocomposites with core-shell structures and magnetic separation performance. Using various characterization methods and model reactions the relationship between the structure of Ni?NCFs (nickel-nitrogen-doped carbon frameworks) and catalytic performance was investigated, and the results show that there is a positive correlation between the catalytic performance and hydrophobicity of catalysts. Besides, the possible catalytically active sites, which are formed by the interaction of pyridinic N and graphitic N in the structure of nitrogen-doped graphene with the surfaces of Ni nanoparticles, should be pivotal to achieving the relatively high catalytic performance of materials. Due to its unique structure, the obtained Ni?NCF-700 catalyst with superhydrophobicity shows extraordinary performances toward the hydrogen transfer reaction of nitrobenzene and N-heterocycles in the aqueous state; meanwhile, it was also found that Ni?NCF-700 still retained its excellent catalytic activity and structural integrity after three cycles. Compared with traditional catalytic systems, our catalytic systems offer a highly effective, green and economical alternative for nitrobenzene and N-heterocycle transformation, and may open up a new avenue for simple construction of structure and activity defined carbon nanocomposite heterogeneous catalysts with superhydrophobicity.
- Duan, Zhiying,Liu, Fangfang,Pang, Shaofeng,Su, Qiong,Wang, Yanbin,Xie, Xin,Zhang, Ping,Zhang, Yujing,Zhou, Feng
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p. 1996 - 2010
(2020/04/07)
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- Lidocaine hydrochloride 1(1/5)hydrate compound
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The invention discloses a lidocaine hydrochloride 1(1/5)hydrate compound and a preparation method thereof, wherein the compound is determined by a powder X-ray diffraction determination method, and characteristic diffraction peaks are displayed at 6.7 degrees, 13.5 degrees, 16.6 degrees, 20.2 degrees, 27.1 degrees and 34.0 degrees by 2 [theta]+/-0.2 degree diffraction angles. The lidocaine hydrochloride 1(1/5)hydrate compound prepared by the method has the advantages of good thermal stability, high purity and weak hygroscopicity, and is simple in process, high in yield, strong in repeatabilityand suitable for industrial production.
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Paragraph 0083-0084
(2020/01/03)
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- Superfine CoNi alloy embedded in Al2O3 nanosheets for efficient tandem catalytic reduction of nitroaromatic compounds by ammonia borane
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Aromatic amino compounds are important and universally used chemical intermediates in a wide range of industrial fields. Thus, their production with high efficiency and selectivity under ambient conditions is expected and demanded in modern industry. Herein, a series of superfine CoNi alloy nanoparticles embedded in Al2O3 nanosheet (CoxNi1-x/Al2O3, where x represents the content of Co in the precursor) catalysts was fabricated from CoNiAl-LDH and used to catalyze the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of nitroaromatics to the corresponding amines. Systematic experiments indicate that the composition, size, morphology and catalytic performance of the CoxNi1-x/Al2O3 catalysts can be easily controlled by changing the content of Ni in the CoNiAl-LDH precursor. Particularly, Co0.67Ni0.33/Al2O3 exhibited the best tandem catalytic performance among the six samples. This as-prepared catalyst not only showed a moderate turn-over-frequency value (TOF: 34.5 molH2 molCo0.67Ni0.33-1 min-1 at 298 K without base or additives) and relatively low activation energy (32.4 kJ mol-1) for the dehydrogenation of AB, but also superior catalytic activity (conversion yield reaching up to 100%) and selectivity (>99%) for the tandem reductive transformation of in excess of sixteen types of nitroaromatics to aromatic amines. Density functional theory (DFT) calculations suggest that the construction of the CoNi alloy optimized the electronic structure with respect to the pure component, promoting its activity for AB hydrolysis and nitroaromatics hydrogenation. Finally, the catalyst could be easily recycled using a magnet due to the magnetic properties of the Co0.67Ni0.33 alloy.
- Cheng, Sihang,Liu, Yanchun,Zhao, Yingnan,Zhao, Xinyu,Lang, Zhongling,Tan, Huaqiao,Qiu, Tianyu,Wang, Yonghui
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p. 17499 - 17506
(2019/12/23)
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- Hydrogenation of nitroarenes to anilines in a flow reactor using polystyrene supported rhodium in a catalyst-cartridge (Cart-Rh@PS)
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The present methodology described the chemo-selective hydrogenation of various nitroarenes in a flow reactor under polystyrene supported rhodium in a catalyst-cartridge (Cart-Rh@PS) as a heterogeneous nano-catalyst. The polystyrene supported Rh (Rh@PS) nanoparticles (NPs) were prepared by following our earlier reported protocol and packed inside the catalyst-cartridge (Cat-Cart) to obtain Cart-Rh@PS, which is compatible with ThalesNano's H-Cube Pro flow system. The advantages of the prepacked catalyst Cart-Rh@PS are as follows: no need for catalyst activation up to 12 runs, negligible metal leaching detected by ICP-AES analysis and significantly less back pressure generated under the flow conditions. The same catalyst, Cart-Rh@PS, was also effective up to a 1 gram scale for the reduction of nitroarenes and reusable for successive runs. The hydrogenation in the flow reactor is a greener approach for the reduction of nitroarenes to their corresponding anilines in high yields.
- Sharma, Saurabh,Yamini,Das, Pralay
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supporting information
p. 1764 - 1769
(2019/01/28)
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- The immobilized Ni(II)-thiourea complex on silica-layered copper ferrite: A novel and reusable nanocatalyst for one-pot reductive-acetylation of nitroarenes
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In this study, magnetically nanoparticles of CuFe2O4@SiO2@PTMS@Tu@Ni(II) as novel and reusable catalyst were prepared. Synthesis of the Ni (II)-nanocatalyst was carried out through the complexation of Ni(OAc)2·4H2O with the immobilized thiourea on silica-layered CuFe2O4. The prepared nanocomposite system was then characterized using SEM, EDX, XRD, VSM, ICP-OES, Raman, UV–Vis and FT-IR analyses. Catalytic activity of the Ni(II)-CuFe2O4 system was investigated towards rapid reduction of aromatic nitro compounds to arylamines with sodium borohydride as well as one-pot reductive-acetylation of nitroarenes to acetanilides with NaBH4/Ac2O system without the isolation of intermediate arylamines. All reactions were carried out in H2O within 3–7?min to afford the products arylamines/acetanilides in high to excellent yields. Reusability of the Ni(II)-nanocatalyst was examined for seven consecutive cycles without the significant loss of the catalytic activity.
- Zeynizadeh, Behzad,Shokri, Zahra,Hasanpour Galehban, Morteza
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- Controllable synthesis of azoxybenzenes and anilines with alcohol as the reducing agent promoted by KOH
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Nitrobenzene and its derivatives can be selectively reduced to the corresponding azoxybenzene and aniline compounds with alcohols as the hydrogen source and KOH as the promoter only by simple changes of reaction conditions.
- Wei, Rui Ping,Shi, Feng
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p. 688 - 696
(2019/02/16)
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- Ultrafine NiMoOx nanoparticles confined in mesoporous carbon for the reduction of nitroarenes: effect of the composition and accessibility of the active sites
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The design of ultrafine NiMoOx nanoparticles (NPs) confined in hierarchically porous carbon remains a great challenge due to its high calcination temperature. In addition, the composition of active sites of NiMoOx NPs for the hydrogenation reaction is still ambiguous. Herein, we report a general approach for the synthesis of ultrafine NiMoOx NPs confined in mesoporous carbon with different morphologies and compositions using the replication method with SBA-15 as a hard template. The pore structure of mesoporous carbon and the Ni/Mo composition valence-state were discovered to be the main factors in the reduction of nitroarenes. The NiMoOx/mesoporous carbon-platelet (NiMoOx/MC-PL) with short mesochannels (~350 nm) and high surface area (~995 m2 g?1) possessed excellent catalytic activity towards the reduction of 4-nitrophenol, whereas NiMoOx/mesoporous carbon-hexagonal-prism (NiMoOx/MC-HP), NiMoOx/mesoporous carbon-long-rod (NiMoOx/MC-LR), and NiMoOx/mesoporous carbon-spherical (NiMoOx/MC-SP) with long mesochannels and relatively less surface area exhibited poor catalytic performance. The bifunctional mechanism or electronic synergistic effects of Ni and Mo species enhanced their catalytic performance. A good balance between MoOx and metallic Ni (NiMoOx/MC-PL-450) was found to be suitable for the reduction of 4-NP.
- Li, Shuna,Lv, Yipin,Song, Guolong,Li, Cuncheng,Gao, Daowei,Chen, Guozhu
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p. 4571 - 4582
(2019/02/26)
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- Nainai non-west tanzania intermediate 2, 6 - dimethyl aniline synthesis method
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The invention discloses a nainai non-west tanzania intermediate 2 - pyrrolidone synthetic method, the 4 - amino - 3 - methyl benzoate with halogenated methane under the effects of catalyst obtained by reaction of 2, 6 - dimethyl aniline, the 4 - amino - 3 - methyl benzoate, protective agent and solvent A reaction mixture obtained from I; halogenated methane, catalyst and solvent B mixing, then mixing the mixture I II into the reaction mixture; adding an aqueous solution of hydrochloric acid in the reaction mixture is mixed with the mixture II III; III will be alkali water dripped into the mixture, the reaction mixture obtained from IV; the mixture is poured into the IV 3 - 4 times of the volume of water, added with a solvent extracting C, layered, organic layer after the water washing, after drying agent, concentrated evaporate the solvent to obtain the product. The method of low cost, high yield, blowdown less.
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Paragraph 0032; 0039; 0040; 0050; 0057; 0058
(2019/06/13)
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- Hydrogenation of nitroarenes catalyzed by a dipalladium complex
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A dipalladium complex [Pd2(L)Cl2](PF6)2 (2), via the substitution of (PhCN)2PdCl2 with 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L) followed by the anion exchange, was found to be a good pre-catalyst for the reduction of nitroarenes to yield the corresponding anilines under atmospheric pressure of hydrogen in methanol. This method provides a straightforward access to a diverse array of functionalized anilines, exhibiting a possible application in synthetic chemistry. The catalytic activity of this complex is enhanced by the di-metallic system via the synergistic effect.
- Hung, Ming-Uei,Yang, Shu-Ting,Ramanathan, Mani,Liu, Shiuh-Tzung
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- Highly efficient reduction of nitro compounds: Recyclable Pd/C-catalyzed transfer hydrogenation with ammonium formate or hydrazine hydrate as hydrogen source
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Herein, we described a highly efficient heterogeneous Pd/C-catalyzed transfer hydrogenation of nitro compounds for the synthesis of primary amines, using ammonium formate and hydrazine hydrate as hydrogen source independently. The products were obtained with up to >99% yield. Furthermore, gram scale and recycling of catalyst had been tested with well results.
- Chen, Xia,Zhou, Xiao-Yu,Wu, Hong,Lei, Yi-Zhu,Li, Jin-Hui
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supporting information
p. 2475 - 2484
(2018/10/25)
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- Supported Rhodium Nanoparticles Catalyzed Reduction of Nitroarenes, Arylcarbonyls and Aryl/Benzyl Sulfoxides using Ethanol/Methanol as In Situ Hydrogen Source
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A facile reduction reaction of nitroarenes, aryl carbonyls and aryl/benzyl sulfoxides was performed under polystyrene supported rhodium (Rh@PS) catalyzed conditions using ethanol/methanol as in situ hydrogen source. The catalyst Rh@PS played a pivotal role in the oxidation of ethanol/methanol in the presence of traces of aerial oxygen and base to produce hydrogen gas, enough for further reduction reaction. Transmission electron microscopy (TEM) analysis indicated that the average particle size of the Rh nanoparticles (NPs) lies between 2–3 nm; this is responsible for its high catalytic activity. The advantages of Rh@PS are its catalytic activity, easy preparation, recovery, recyclability for several runs, and low metal leaching during reaction. (Figure presented.).
- Sharma, Saurabh,Bhattacherjee, Dhananjay,Das, Pralay
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supporting information
p. 2131 - 2137
(2018/04/17)
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- Synthesis of magnetic Fe3O4@SiO2@Cu–Ni–Fe–Cr LDH: an efficient and reusable mesoporous catalyst for reduction and one-pot reductive-acetylation of nitroarenes
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Abstract: Magnetically recoverable Fe3O4@SiO2@Cu–Ni–Fe–Cr LDH was prepared under co-precipitation conditions. Characterization of the mesoporous catalyst was confirmed using Fourier-transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibration sample magnetometer, Brunauer–Emmett–Teller, thermogravimetric, differential thermogravimetric analyses and transmission electron microscopy. Reduction of nitroarenes to the corresponding arylamines and one-pot reductive-acetylation of nitroarenes to acetanilides were carried out successfully by nanoparticles of the immobilized Cu–Ni–Fe–Cr layered double hydroxide on silica-coated Fe3O4 in water as a green solvent. All reactions were carried out within 6–22?min affording arylamines and N-arylacetamides in high-to-excellent yields. Reusability of the core–shell nanocatalyst was examined six times without significant loss of its catalytic activity.
- Gilanizadeh, Masumeh,Zeynizadeh, Behzad
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p. 2821 - 2837
(2018/10/31)
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- Synthesis of six 8-quinolinate-based ruthenium complexes with high catalytic activity for nitroarene reduction
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Six ruthenium complexes were synthesized by treating different 2-substituted 8-hydroxyquinolinate ligands with [Ru(p-cymene)(μ-Cl)Cl]2. Their structures were fully characterized by a variety of techniques, including 1H and 13C NMR spectra, elemental analyses and infrared spectrometry. Additionally, single-crystal X-ray diffraction reveals that these ruthenium complexes possess similar half-sandwich structures. The mononuclear ruthenium building units are further linked into 1D or 2D supramolecular structures through non-covalent interactions, such as π?π stacking, hydrogen-bonding and C–H? halogen interactions. The catalytic activities of the six half-sandwich ruthenium complexes towards the hydrogenation of nitroarenes were explored under mild conditions. The ruthenium complexes displayed high catalytic activities in the synthesis of aromatic anilines from nitroarenes in the presence of NaBH4.
- Jia, Wei-Guo,Cheng, Ming-Xia,Xu, Qiu-Tong,Gao, Li-Li,Yuan, Guozan
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- Nitro group reduction and Suzuki reaction catalysed by palladium supported on magnetic nanoparticles modified with carbon quantum dots generated from glycerol and urea
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Glycerol and urea were used as green and cheap sources of carbon quantum dots (CQD) for modifying Fe3O4 nanoparticles (NPs). The obtained CQD@Fe3O4 NPs were used for the stabilization of palladium species and the prepared catalyst, Pd@CQD@Fe3O4, was characterized using various techniques. This magnetic supported palladium was applied as an efficient catalyst for the reduction of aromatic nitro compounds to primary amines at room temperature using very low palladium loading (0.008?mol%) and also for the Suzuki–Miyaura cross-coupling reaction of aryl halides as well as challenging heteroaryl bromides and aryl diazonium salts with arylboronic acids and with potassium phenyltrifluoroborate. This magnetically recyclable catalyst was recovered and reused for seven consecutive runs in the reduction of 4-nitrotoluene to p-toluidine and for ten consecutive runs in the reaction of 4-iodoanisole with phenylboronic acid with small decrease of activity. The catalyst reused in the Suzuki reaction was characterized using transmission electron microscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy. Using experiments such as hot filtration and poisoning tests, it has been shown that the true catalyst works under homogeneous conditions according to the release–return pathway of active palladium species.
- Gholinejad, Mohammad,Zareh, Fatemeh,Nájera, Carmen
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- MOF-Derived Cobalt Phosphide/Carbon Nanocubes for Selective Hydrogenation of Nitroarenes to Anilines
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Transition-metal phosphides have received tremendous attention during the past few years because they are earth-abundant, cost-effective, and show outstanding catalytic performance in several electrochemically driven conversions including hydrogen evolution, oxygen evolution, and water splitting. As one member of the transition-metal phosphides, CoxP-based materials have been widely explored as electrocatalyts; however, their application in the traditional thermal catalysis are rarely reported. In this work, cobalt phosphide/carbon nanocubes are designed and their catalytic activity for the selective hydrogenation of nitroarenes to anilines is studied. A high surface area metal-organic framework (MOF), ZIF-67, is infused with red phosphorous, and then pyrolysis promotes the facile production of the phosphide-based catalysts. The resulting composite, consisting of Co2P/CNx nanocubes, is shown to exhibit excellent catalytic performance in the selective hydrogenation of nitroarenes to anilines. To the best of our knowledge, this is the first report showing catalytic activity of a cobalt phosphide in nitroarenes hydrogenation.
- Yang, Shuliang,Peng, Li,Oveisi, Emad,Bulut, Safak,Sun, Daniel T.,Asgari, Mehrdad,Trukhina, Olga,Queen, Wendy L.
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supporting information
p. 4234 - 4238
(2018/03/30)
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- Unprecedented catalytic performance in amine syntheses: Via Pd/g-C3N4 catalyst-assisted transfer hydrogenation
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The preparation of amine compounds is very important for both the chemical industry and renewable feedstock processing. Nevertheless, difficulties remain in finding a catalytic system that is sufficiently active and environmentally benign for producing amine compounds. In this work, we report that g-C3N4 nanosheets as support materials can significantly boost the efficiency of Pd nanoparticles for the reduction of nitro compounds to primary amines. Using formic acid as a hydrogen donor and water as a solvent, the optimized 5 wt% Pd/g-C3N4 catalyst exhibited an unprecedented performance in the conversion of nitrobenzene into aniline (achieving almost full conversion with an extremely high turnover frequency of 4770 h-1 at room temperature), yielding the best activity ever reported for heterogeneously catalyzing nitro compound reduction. Pd/g-C3N4 catalyst was also active for the one-pot reductive amination of carbonyl compounds with nitro compounds to obtain the corresponding secondary amines with excellent selectivity (>90%). We proposed that the protic N-H+ and hydridic Pd-H- on Pd/g-C3N4 are the active species for the transfer hydrogenation reaction of nitro compounds. Furthermore, Pd/g-C3N4 catalyst was highly stable with a wide scope in the syntheses of various amine compounds. This work will open up a new approach for the transfer hydrogenations of nitro compounds to produce primary or secondary amines in green chemistry.
- Xu, Xingliang,Luo, Jiajun,Li, Liping,Zhang, Dan,Wang, Yan,Li, Guangshe
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p. 2038 - 2046
(2018/05/24)
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- Metal–Organic-Framework-Derived Co3S4 Hollow Nanoboxes for the Selective Reduction of Nitroarenes
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MOF-derived Co3S4/CN hollow nanoboxes (CN=nitrogen-doped carbon) was used to catalyze the chemoselective reduction of nitroarenes to anilines under mild reaction conditions with H2 as the reducing agent. The catalyst provides high conversion efficiencies and selectivities for a variety of nitroarene substrates that contain electron-donating or electron-withdrawing substituents under mild reaction conditions (in methanol at 60 °C). Further, the nanobox inhibits both dehalogenation and vinyl hydrogenation reactions, which are common limitations of state-of-the-art Pd-based catalysts. Because the reactions result in pure aniline products, the need for separation by column chromatography is eliminated. The resulting anilines are easily separated from the methanolic reaction solution in just three simple steps (centrifugation, decantation, and drying). If employed in industrial processes, catalysts of this kind would significantly reduce the amount of waste organic solvent generated and thus satisfy the need for sustainable chemical processes.
- Yang, Shuliang,Peng, Li,Sun, Daniel T.,Oveisi, Emad,Bulut, Safak,Queen, Wendy L.
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p. 3131 - 3138
(2018/09/06)
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- Converting Hierarchical to Bulk Structure: A Strategy for Encapsulating Metal Oxides and Noble Metals in Zeolites
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Encapsulating catalytically active components into zeolites is a way to prepare multifunctional catalysts with unique selectivity and enhanced stability. Previously reported methods for encapsulation were only suitable for encapsulating specific species with a limited loading capacity. Here, we report a general strategy for encapsulating various metal oxides in zeolites. Our strategy is based on the use of directly synthesized hierarchical zeolites with abundant intracrystalline mesopores. Metal oxides that are preloaded in the mesopores by impregnation become encapsulated during a secondary growth process that converts the original hierarchical structure into a bulk structure of zeolite. This method enables the encapsulation of ultrafine particles (2-4 nm) of various metal oxides (CeO2, TiO2, and MnOx) in zeolites with loading as high as >10 wt %. Furthermore, we modify this method to achieve the encapsulation and high dispersion of noble metals (Au and Pt), which would otherwise agglomerate into large particles on the zeolite surfaces, by taking advantage of their strong interactions with metal oxides. The encapsulated metal oxides and metal oxide-supported noble metals demonstrate reactant selectivity, product selectivity, and excellent thermal stability during catalytic oxidation and hydrogenation reactions.
- Wang, Jianjian,Liu, Lingmei,Dong, Xinglong,Alfilfil, Lujain,Hsiung, Chia-En,Liu, Zhaohui,Han, Yu
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p. 6361 - 6369
(2018/09/18)
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- Intramolecular alkene hydroamination and degradation of amidines: Divergent behavior of rare earth metal amidinate intermediates
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Direct N-H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N-alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.
- Zhang, Dexing,Liu, Ruiting,Zhou, Xigeng
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p. 5573 - 5581
(2018/11/20)
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- Selective Cross-Coupling of (Hetero)aryl Halides with Ammonia to Produce Primary Arylamines using Pd-NHC Complexes
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Herein we report the first example of (hetero)arylation of ammonia using a monoligated palladium-NHC complex. The new, rationally designed, precatalyst (DiMeIHeptCl)Pd(allyl)Cl featuring highly branched alkyl chains has been shown to be effective in selective aminations across a range of challenging substrates, including nitrogen-containing heterocycles and those featuring base-sensitive functionality. The less bulky Pd-PEPPSI-IPentCl precatalyst performs well for ortho-substituted aryl halides, giving monoarylated products in high yield with good selectivity.
- Lombardi, Christopher,Day, Jonathan,Chandrasoma, Nalin,Mitchell, David,Rodriguez, Michael J.,Farmer, Jennifer L.,Organ, Michael G.
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supporting information
p. 251 - 254
(2017/04/26)
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- Hydroxyl-containing half-sandwich rutheniumcoordination compound, preparation method and method for reducing nitrobenzene compound into aniline compound
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The invention discloses a hydroxyl-containing half-sandwich rutheniumcoordination compound, a preparation method and a method for reducing nitrobenzene compounds into aniline compounds. A structure of the hydroxyl-containing half-sandwich rutheniumcoordination compound is as shown by formula (I), where X is halogen and R is H, hydrocarbonyl of C1 to C6 or halogen. By adopting the method, the high-yield half-sandwich rutheniumcoordination compound can be prepared under mild conditions, and the half-sandwich rutheniumcoordination compound can reduce nitrobenzene compounds into aniline compounds under mild conditions.
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Paragraph 0080; 0103; 0104; 0105
(2017/06/02)
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- A photocatalytic green system for chemoselective reduction of nitroarenes
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A highly efficient photocatalytic reduction of nitroarenes using TiO2/polyethylene glycol 400-water (TiO2/PEG-H2O) is reported. This system at deoxygenated and illuminated (sunlight or violet LED) conditions efficiently reduced nitroarenes using oxalic acid or ammonium formate as a sacrificial electron donor. Reducible functional groups such as chloro, hydroxy, flouro, bromo and carbonyl were intact under the optimized reaction conditions. The 0.1 and 0.5-1 mmol amount of nitroarenes was used under sunlight and violet LED (400 nm) irradiation, respectively. Reusability of the nanotitania was successfully carried out four times. The analyses of the recovered catalyst after five runs including TEM, XRD, TGA and CHN were done and results showed that PEG is located on TiO2; no change in morphology, crystallinity and particle sizes was observed.
- Ramdar, Moosa,Kazemi, Foad,Kaboudin, Babak
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p. 1155 - 1163
(2017/05/17)
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- Catalytic Reduction of Nitroarenes by Dipalladium Complexes: Synergistic Effect
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The direct reaction between 2,7-bis(2-pyridinyl)-1,8-naphthyridine (bpnp) and Pd(CH3COO)2 in CF3COOH yields the new dinuclear palladium(II) complex [Pd2(bpnp)(μ-OH)(CF3CO2)2](CF3CO2) (1). Similarly, substitution of Pd(CH3CN)4(BF4)2 with bpnp in DMF gives [Pd2(bpnp)(μ-OH)(DMF)2](BF4)3 (2). Treatment of 1 or 2 with Cl- readily provide the chloro-substituted species [Pd(bpnp)(μ-OH)(Cl)2]+. All complexes were characterized by spectroscopic methods, and the structure of 2 was further confirmed by X-ray crystallography. Complex 1 is an efficient catalyst for the reduction of aromatic nitro compounds leading to the corresponding aniline derivatives under atmospheric pressure of hydrogen at 50 °C. The mechanistic pathway of the catalysis is investigated. From the reaction pathway, it is suggested that a facile condensation of nitroso and hydroxylamine intermediates is enabled by the dipalladium system and the desired transformation proceeds smoothly under mild reaction conditions to yield the reduced product.
- Yang, Shu-Ting,Shen, Peng,Liao, Bei-Sih,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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supporting information
p. 3110 - 3116
(2017/09/05)
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- Copper-Based Intermetallic Electride Catalyst for Chemoselective Hydrogenation Reactions
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The development of transition metal intermetallic compounds, in which active sites are incorporated in lattice frameworks, has great potential for modulating the local structure and the electronic properties of active sites, and enhancing the catalytic activity and stability. Here we report that a new copper-based intermetallic electride catalyst, LaCu0.67Si1.33, in which Cu sites activated by anionic electrons with low work function are atomically dispersed in the lattice framework and affords selective hydrogenation of nitroarenes with above 40-times higher turnover frequencies (TOFs up to 5084 h-1) than well-studied metal-loaded catalysts. Kinetic analysis utilizing isotope effect reveals that the cleavage of the H-H bond is the rate-determining step. Surprisingly, the high carrier density and low work function (LWF) properties of LaCu0.67Si1.33 enable the activation of hydrogen molecules with extreme low activation energy (Ea = 14.8 kJ·mol-1). Furthermore, preferential adsorption of nitroarenes via a nitro group is achieved by high oxygen affinity of LaCu0.67Si1.33 surface, resulting in high chemoselectivity. The present efficient catalyst can further trigger the hydrogenation of other oxygen-containing functional groups such as aldehydes and ketones with high activities. These findings demonstrate that the transition metals incorporated in the specific lattice site function as catalytically active centers and surpass the conventional metal-loaded catalysts in activity and stability.
- Ye, Tian-Nan,Lu, Yangfan,Li, Jiang,Nakao, Takuya,Yang, Hongsheng,Tada, Tomofumi,Kitano, Masaaki,Hosono, Hideo
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p. 17089 - 17097
(2017/12/06)
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- An efficient method for reduction of nitroaromatic compounds to the corresponding aromatic amines with NH2NH2·H2O catalysed by H2O2-treated activated carbon
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An efficient and green protocol for the reduction of nitroaromatic compounds to the corresponding amines has been developed. The reduction catalyst system includes NH2NH2·H2O and H2O2-treated activated carbon. Without adding additional metals, the H2O2-treated activated carbon could be reused for many cycles without decreasing catalytic efficiency. The aromatic amines could be obtained in good to excellent yields.
- Jiang, Yuqin,Suo, Huajun,Zhang, Dandan,Li, Xiyong,Sun, Yamin,Ren, Baoqi,Zhang, Weiwei,Xu, Guiqing
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p. 509 - 512
(2017/10/03)
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