- In Situ Synthesized Silica-Supported Co@N-Doped Carbon as Highly Efficient and Reusable Catalysts for Selective Reduction of Halogenated Nitroaromatics
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Silica-supported Co@N-doped carbon (Co@CN/SiO2) catalysts were first prepared by a one-step impregnation with a mixed solution of cobalt nitrate, glucose and urea, followed by in situ carbonization and reduction. The Co@CN/SiO2 catalysts were investigated for the selective reduction of nitro aromatics to the corresponding anilines using hydrazine hydrate. The Co@CN/SiO2-500 carbonized at 500 °C exhibited the highest catalytic activity and excellent stability without any decay of activity after 6 cycles for the reduction of nitrobenzene. Both metallic Co atoms and Co?N species formed in the Co@CN/SiO2 catalysts were active, but the Co?N species were dominant active sites. The high activities of the Co@CN/SiO2 catalysts were attributed to the synergistic effect between the Co and N atoms, promoting heterolytic cleavage of hydrazine to form H+/H? pairs. Representative examples demonstrated that the Co@CN/SiO2-500 could completely transform various halogen-substituted nitro aromatics to the corresponding halogenated anilines with high TOFs and selectivity of '99.5 percent.
- Sheng, Yao,Wang, Xueguang,Yue, Shengnan,Cheng, Gonglin,Zou, Xiujing,Lu, Xionggang
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p. 4632 - 4641
(2020/07/30)
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- Highly selective hydrogenation of halogenated nitroarenes over Ru/CN nanocomposites by: In situ pyrolysis
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A highly chemoselective and recyclable ruthenium catalyst for the hydrogenation of halogenated nitroarenes has been prepared via the simple in situ calcination of a mixture of melamine, glucose and ruthenium trichloride. Superfine Ru particles (2.3 ± 0.3 nm) were obtained and highly dispersed in the nitrogen-doped carbon matrix. The Ru/CN catalyst smoothly transforms a variety of halogenated nitroarenes to the corresponding haloanilines with high intrinsic activity (e.g. TOF = 1333 h-1 for p-chloronitrobenzene) and selectivity of more than 99.6percent. Furthermore, through an analysis of the products in the reaction process, it was concluded that there are two parallel reaction pathways (a direct pathway and an indirect pathway) for the hydrogenation of aromatic nitro compounds over the Ru/CN catalyst, and the direct pathway was proved to be dominant in catalyzing the intermediates. This journal is
- Yue, Shengnan,Wang, Xueguang,Li, Shaoting,Sheng, Yao,Zou, Xiujing,Lu, Xionggang,Zhang, Chunlei
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p. 11861 - 11869
(2020/07/28)
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- Pd-Pt/modified GO as an efficient and selective heterogeneous catalyst for the reduction of nitroaromatic compounds to amino aromatic compounds by the hydrogen source
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In this work, different nitroaromatic compounds were successfully reduced to their corresponding aromatic amines with excellent conversion and selectivity in methanol at 50?°C by using Pd-Pt nanoparticles immobilized on the modified grapheme oxide (m-GO) and hydrogen as the reducing source. The catalytic efficiency of Pd and Pd-Pt loading on the modified GO was investigated for the reduction of various nitroaromatic compounds, and the Pd-Pt/m-GO system demonstrated the highest conversion and selectivity. The catalyst was characterized by different techniques including FT-IR, Raman, UV–Vis, XRD, BET, XPS, FESEM, EDS, and TEM. The metal nanoparticles with the size of less than 10?nm were uniformly distributed on the m-GO. The catalyst could be reused at least five times without losing activity, showing the stability of the catalyst structure. Finally, the efficiency of the prepared catalyst was compared with Pd-Pt/AC, and Pd-Pt/GO catalysts.
- Salahshournia, Hossein,Ghiaci, Mehran
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- Copper-Mediated monochlorination of anilines and nitrogen-containing heterocycles
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A simple and selective copper(II) chloride-mediated monochlorination of anilines and nitrogen-containing heterocycles has been developed. Stirring a mixture of aniline, copper(II) chloride, lithium chloride in EtOH under reflux condition produced 4-chloroaniline with high yield. Eighteen substrates including substituted anilines, N-substituted anilines, N,N-disubstituted anilines, 5-nitroindole and carbazole were all reactive and afforded desired products in moderate to excellent yields (52%–98%).
- Yang, Xue-Yan,Zhao, Hong-Yi,Mao, Shuai,Zhang, San-Qi
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supporting information
p. 2708 - 2714
(2018/10/15)
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- Chemoselective transfer hydrogenation of nitroarenes by highly dispersed Ni-Co BMNPs
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Highly dispread Ni-Co bimetallic nanoparticles (Ni-Co BMNPs) are synthesized and applied as an efficient catalyst in the chemoselective transfer hydrogenation of nitroarenes (CTH) using hydrazine hydrate as the hydrogen donor. The BMNPs can efficiently catalyze the reduction reaction without any additives under mild conditions with high TOF. Significantly higher activity is achieved when compared with corresponding single-component catalysts, optimal composition of the Ni-Co BMNPs was screened which was proved to be crucial in both the selectivity and yields. Excellent performance of Ni-Co BMNPs can be ascribed to the improved dispersion of active sites on the BMNPs surface (compared with Ni NPs) and the electron transfer from cobalt to nickel.
- Zhang, Jia-Wei,Lu, Guo-Ping,Cai, Chun
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- Iridium-catalyzed transfer hydrogenation of nitroarenes to anilines
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A simple and general homogeneous catalyst system composed of commercially available [Ir(cod)Cl]2 and 1,10-phenanthroline has been developed for the selective transfer hydrogenation of nitroarenes to anilines. It utilized the readily accessible 2-propanol as a hydrogen donor and had wide substrate scope. A careful mechanistic investigation through real-time detection and a series of controlled experiments with possible intermediates was also carried out, which showed that the transformation proceeds via both phenylhydroxylamine and azobenzene intermediates and the reduction of hydrazobenzene leading to aniline might be the rate-determining step.
- Chen, Shujie,Lu, Guoping,Cai, Chun
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p. 5360 - 5365
(2015/07/07)
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- Dialkylimidazole inhibitors of Trypanosoma cruzi sterol 14α-demethylase as anti-Chagas disease agents
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New dialkylimidazole based sterol 14α-demethylase inhibitors were prepared and tested as potential anti-Trypanosoma cruzi agents. Previous studies had identified compound 2 as the most potent and selective inhibitor against parasite cultures. In addition, animal studies had demonstrated that compound 2 is highly efficacious in the acute model of the disease. However, compound 2 has a high molecular weight and high hydrophobicity, issues addressed here. Systematic modifications were carried out at four positions on the scaffold and several inhibitors were identified which are highly potent (EC50 1 nM) against T. cruzi in culture. The halogenated derivatives 36j, 36k, and 36p, display excellent activity against T. cruzi amastigotes, with reduced molecular weight and lipophilicity, and exhibit suitable physicochemical properties for an oral drug candidate.
- Suryadevara, Praveen Kumar,Racherla, Kishore Kumar,Olepu, Srinivas,Norcross, Neil R.,Tatipaka, Hari Babu,Arif, Jennifer A.,Planer, Joseph D.,Lepesheva, Galina I.,Verlinde, Christophe L.M.J.,Buckner, Frederick S.,Gelb, Michael H.
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supporting information
p. 6492 - 6499
(2013/11/19)
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- Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids
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By using ionic liquids as solvents, the chlorination or bromination of unprotected anilines at the para-position can be achieved in high yields with copper halides under mild conditions, without the need for potentially hazardous operations such as supplementing oxygen or gaseous HCl.
- Wang, Han,Wen, Kun,Nurahmat, Nurbiya,Shao, Yan,Zhang, He,Wei, Chao,Li, Ya,Shen, Yongjia,Sun, Zhihua
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supporting information; experimental part
p. 744 - 748
(2012/06/30)
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- Aromatic substitution in ball mills: Formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
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Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed. The Royal Society of Chemistry.
- Schmidt, Robert,Stolle, Achim,Ondruschka, Bernd
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p. 1673 - 1679
(2013/02/22)
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- Novel ZnX2-modulated Pd/C and Pt/C catalysts for chemoselective hydrogenation and hydrogenolysis of halogen-substituted nitroarenes, alkenes, benzyl ethers, and aromatic ketones
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Novel ZnX2-modulated Pd/C and Pt/C catalysts were developed to chemoselectively hydrogenate halogen-substituted nitroarenes, alkenes, benzyl ethers, and aromatic ketones.
- Wu, George,Huang, Mingsheng,Richards, Monique,Poirier, Marc,Wen, Xin,Draper, Richard W.
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p. 1657 - 1660
(2007/10/03)
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- Imidazolylacetic acid amides
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Imidazolylacetic acid amides of the formula: SPC1 Or pharmaceutically acceptable nontoxic salts thereof wherein Either R1 is phenyl or cycloalkyl, unsubstituted or substituted by one or more substituents; and R2 is hydrogen; Or R1 and R2, together with the nitrogen atom to which they are attached, form a saturated 5 to 7-membered heterocyclic ring which ring may contain an --SO2 -- or --NY-- moiety wherein Y is alkoxycarbonyl, dialkylaminocarbonyl, or phenyl or diphenylmethyl, unsubstituted or substituted by one or more substituents and wherein said 5 to 7-membered heterocyclic ring itself is otherwise unsubstituted or substituted by one or more substituents; and X1, x2, x3 and X4 are the same or different and are each hydrogen or halogen, Are produced by A. reacting a halodiphenylacetic acid amide of the formula: SPC2 Wherein R1, r2, x1, x2, x3 and X4 are as above defined, and Hal is halogen, With imidazole; or B. reacting a halodiphenylacetic acid halide of the formula: SPC3 Wherein X1, x2, x3 and X4 are as above defined and Hal is halogen With imidazole to produce an imidazolide of the formula: SPC4 Wherein X1, x2, x3 and X4 are as above defined which in turn is transaminated by reaction with an amine of the formula: wherein R1 and R2 are as above defined.
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