- Preparation and catalytic performance of active metal sintered membrane reactor anchored with Pt atoms
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In the chemical industry, reactors are typically designed and filled with supported catalyst particles. However, the intrinsic problems associated with the internal/external diffusion effect and catalyst separation/loss in these traditional reactors can be very challenging to mitigate. To address these issues, herein, an active metal sintered membrane reactor anchored with Pt atoms was successfully developed, and applied into continuous, liquid-phase, hydrogenation processes. The catalyzing reactions transpired on the active sites that were fastened onto the surface of the reactor's microchannels. As a result, the mass transfer at the gas-liquid-solid three-phase was greatly enhanced, and an incredibly high reaction efficiency was obtained. The novel, active reactor demonstrated a superior catalytic performance and stability to nitrobenzene (NB) hydrogenation at 120 °C and 0.5 MPa H2, which enabled an aniline (ANI) yield of 19.28 molANI h-1 L-1. This work opens a new window for the design of high-performance gas-liquid-solid reactor toward multiphase catalytic reactions. This journal is
- Ren, Xiaoliang,Wang, Shufang,Ding, Xiaoshu,Zhang, Dongsheng,Wang, Yanji
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p. 2848 - 2853
(2021/01/28)
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- Designing of Highly Active and Sustainable Encapsulated Stabilized Palladium Nanoclusters as well as Real Exploitation for Catalytic Hydrogenation in Water
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Abstract: Encapsulated nanoclusters based on palladium, 12-tunstophosphoric acid and silica was designed by simple wet impregnation methodology. The catalyst was found to be very efficient towards cyclohexene hydrogenation up to five catalytic runs with substrate/catalyst ratio of 4377/1 at 50?°C as well as for alkene, aldehyde, nitro and halogen compounds. Graphic Abstract: Silica encapsulated Pd nanoclusters stabilized by 12-tungstophosphoric acid is proved to be sustainable and excellent for water mediated hydrogenation reaction with very high catalyst to substrate ratio as well as TON.[Figure not available: see fulltext.]
- Patel, Anish,Patel, Anjali
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p. 803 - 820
(2020/08/12)
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- Fabrication of palladium nanocatalyst supported on magnetic eggshell and its catalytic character in the catalytic reduction of nitroarenes in water
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Aromatic nitro compounds, which have good solubility in water, are highly toxic and non-biodegradable are one of the most important industrial pollutants and have negative effects on human health, aquatic life and the environment. Therefore, the elimination of these harmful organic compounds has become an issue of great importance. For this, in this study we have developed a palladium nanocatalyst supported on Fe3O4-coated eggshell and characterized by FT-IR, XRD, XPS, FE-SEM, TG/DTG, BET, TEM and EDS techniques (Pd-Fe3O4-ES). Also, the quantitative analysis of Pd was determined using ICP-OES. The catalytic behavior of the designed Pd-Fe3O4-ES nanocatalyst was investigated against the catalytic reduction of several highly toxic nitro compounds using NaBH4 in water at room temperature. The progress of the reduction was followed using high performance liquid chromatography (HPLC). The catalytic studies revealed that the nitro compounds were converted into the desired amines by the Pd-Fe3O4-ES nanocatalyst using a very low dose of catalyst (15 mg) and short-duration reactions (81–360 s) in aqueous medium at ambient temperature. Furthermore, the Pd-Fe3O4-ES nanocatalyst showed good catalytic stability by retaining its activity after the fifth catalytic run.
- ?al??kan, Melike,Akay, Sema,Baran, Talat,Kayan, Berkant
-
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- Depolymerization of Technical-Grade Polyamide 66 and Polyurethane Materials through Hydrogenation
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Chemical recycling provides a promising solution to utilize plastic waste. Here, a catalytic hydrogenative depolymerization of polyamide 66 (PA 66) and polyurethane (PU) was developed. The system employed Ru pincer complexes at high temperature (200 °C) in THF solution, and even technical-grade polymers could be hydrogenated with satisfactory yields under these conditions. A comparison of the system with some known heterogeneous catalysts as well as catalyst poisoning tests supported the homogeneity of the system. These results demonstrate the potential of chemical recycling to regain building blocks for polymers and will be interesting for the further development of polymer hydrogenation.
- Zhou, Wei,Neumann, Paul,Al Batal, Mona,Rominger, Frank,Hashmi, A. Stephen K.,Schaub, Thomas
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p. 4176 - 4180
(2020/11/30)
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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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-
- Synthesis, characterization, and catalytic activity of half-sandwich ruthenium complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands
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Three half-sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands [Ru(p-cymene)L](PF6)1–2 (1a–1c, L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single-crystalX-ray diffraction methods. Moreover, the half-sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water.
- Jia, Wei-Guo,Du, Teng-Teng,Gao, Li-Li,Du, Jun
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- General and selective synthesis of primary amines using Ni-based homogeneous catalysts
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The development of base metal catalysts for industrially relevant amination and hydrogenation reactions by applying abundant and atom economical reagents continues to be important for the cost-effective and sustainable synthesis of amines which represent highly essential chemicals. In particular, the synthesis of primary amines is of central importance because these compounds serve as key precursors and central intermediates to produce value-added fine and bulk chemicals as well as pharmaceuticals, agrochemicals and materials. Here we report a Ni-triphos complex as the first Ni-based homogeneous catalyst for both reductive amination of carbonyl compounds with ammonia and hydrogenation of nitroarenes to prepare all kinds of primary amines. Remarkably, this Ni-complex enabled the synthesis of functionalized and structurally diverse benzylic, heterocyclic and aliphatic linear and branched primary amines as well as aromatic primary amines starting from inexpensive and easily accessible carbonyl compounds (aldehydes and ketones) and nitroarenes using ammonia and molecular hydrogen. This Ni-catalyzed reductive amination methodology has been applied for the amination of more complex pharmaceuticals and steroid derivatives. Detailed DFT computations have been performed for the Ni-triphos based reductive amination reaction, and they revealed that the overall reaction has an inner-sphere mechanism with H2metathesis as the rate-determining step.
- Beller, Matthias,Chandrashekhar, Vishwas G.,Jagadeesh, Rajenahally V.,Jiao, Haijun,Murugesan, Kathiravan,Wei, Zhihong
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p. 4332 - 4339
(2020/05/18)
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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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- Utilization of a Hydrogen Source from Renewable Lignocellulosic Biomass for Hydrogenation of Nitroarenes
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Exploring of hydrogen source from renewable biomass, such as glucose in alkaline solution, for hydrogenation reactions had been studied since 1860s. According to proposed pathway, only small part of hydrogen source in glucose was utilized. Herein, the utilization of a hydrogen source from renewable lignocellulosic biomass, one of the most abundant renewable sources in nature, for a hydrogenation reaction is described. The hydrogenation is demonstrated by reduction of nitroarenes to arylamines in up to 95 % yields. Mechanism studies suggest that the hydrogenation occurs via a hydrogen transformation pathway.
- Tan, Fang-Fang,Tang, Kai-Li,Zhang, Ping,Guo, Yan-Jun,Qu, Mengnan,Li, Yang
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p. 4189 - 4195
(2019/03/07)
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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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- Hydrogenation of nitroaromatics to anilines catalyzed by air-stable arene ruthenium (II)–NNN pincer complexes
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A series of air-stable, phosphine-free arene ruthenium (II)–NNN pincer complexes (RuL, RuL1, RuL2 and RuL3) have been synthesized and characterized by spectroscopic and single-crystal X-ray analysis. Further, arene ruthenium (II)–NNN pincer complexes have been used as catalyst for hydrogenation of nitroaromatics into aniline in the presence of NaBH4 at room temperature. The catalytic process suggested highly chemo-selective nitroreduction with wide functional group tolerance.
- Pitchaimani, Jayaraman,Gunasekaran, Nanjappan,Anthony, Savarimuthu Philip,Moon, Dohyun,Madhu, Vedichi
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- Synthesis, Characterization, and Catalytic Activities of Palladium Complexes with Phenylene-Bridged Bis(thione) Ligands
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The neutral phenylene-bridged bis(thione) compounds, 1,3-bis(3′-ethylimidazolyl-2′-thione)benzene (Betb), 1,3-bis(3′-butylimidazolyl-2′-thione)benzene (Bbtb), and 1,3-bis(3′-allylimidazolyl-2′-thione)benzene (Batb), have been synthesized and characterized. Reactions of palladium precursor PdCl2(CH3CN)2 with phenylene-bridged bis(thione) ligands in 1:2 ratio resulted in the formation of the complexes: PdCl2(L)2 (L = Betb, 3a; L = Bbtb, 3b; L = Batb, 3c, respectively). In contrast, treatment of the ligands with PdCl2(CH3CN)2 in 1:1 ratio gave cyclometalation palladium complexes Pd2+Cl(L-) (L = Betb-H, 4a; L = Bbtb-H, 4b; L = Batb-H, 4c) through the metal-induced C-H activation. Complexes 4a-c can also be obtained by the reaction of bis(thione) ligands and PdCl2 in 1:1 ratio. The reaction of 3a-c with additional PdCl2(CH3CN)2 also afforded complexes 4a-c. All ligands and palladium complexes were fully characterized by one-/two-dimensional NMR spectra, mass spectrometry, and infrared spectrometry. And the molecular structures of 3a-c, 4a, and 4c have been determined by the single-crystal X-ray diffraction method. Furthermore, the detailed spectroscopic properties and catalytic activities of the complexes for the reduction of nitro compounds were discussed in terms of the modification of the coordination ligands to the center metal.
- Jia, Wei-Guo,Gao, Li-Li,Wang, Zhi-Bao,Sun, Li-Ying,Han, Ying-Feng
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p. 1946 - 1954
(2019/05/08)
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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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- Half-Sandwich Ruthenium Phenolate-Oxazoline Complexes: Experimental and Theoretical Studies in Catalytic Transfer Hydrogenation of Nitroarene
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In this work, five ruthenium complexes [Ru(p-cymene)LCl] containing phenolate-oxazoline ligands [L = 2-(4,5-dihydrooxazol-2-yl)phenol (1); L = 2-(4-methyl-4,5-dihydrooxazol-2-yl)phenol (2); L = 2-(4-ethyl-4,5-dihydrooxazol-2-yl)phenol (3); L = 2-(4-phenyl-4,5-dihydrooxazol-2-yl)phenol (4); and 2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)phenol (5)] were synthesized and characterized. The solid-state structures of all ruthenium complexes were determined by single-crystal X-ray diffraction. The catalytic activities of these complexes in the transfer hydrogenation reaction of nitroarene to aniline were investigated. Aniline and their derivatives were obtained in good to excellent yields with isopropanol as the hydride source. The present protocol provides an environmentally benign synthetic method for the reduction of nitroarenes to anilines without employing harsh reaction conditions. Theoretical studies employing density functional theory were carried with the aim to propose a feasible reaction mechanism and to draw insights into the reactivity of the half-sandwich ruthenium catalyst.
- Jia, Wei-Guo,Ling, Shuo,Zhang, Hai-Ning,Sheng, En-Hong,Lee, Richmond
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- Preparation of Well-Ordered Mesoporous-Silica-Supported Ruthenium Nanoparticles for Highly Selective Reduction of Functionalized Nitroarenes through Transfer Hydrogenation
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MCM-41-type mesoporous silica (OMS-IL) was prepared by using an ionic liquid (1-hexadecyl-3-methylimidazolium bromide) as a template. The XRD and TEM results demonstrated that OMS-IL was more stable than the MCM-41 material. Ru nanoparticles were supported on OMS-IL (Ru/OMS-IL) by impregnating OMS-IL with a RuCl3 aqueous solution, and the resulting material was used for the selective reduction of nitroarenes. The effects of the components of the catalysts and the reaction conditions on the catalytic behavior of the prepared catalysts were investigated in detail. Ru/OMS-IL exhibited high catalytic activity and chemoselectivity for the reduction of various substituted nitroarenes to the corresponding aromatic amines in ethanol with hydrazine hydrate as a hydrogen donor under mild conditions. The Ru/OMS-IL catalysts were highly stable and could easily be recovered by simple filtration over at least six recycling reactions without any observable loss in catalytic performance.
- Wei, Ning,Zou, Xiujing,Huang, Haigen,Wang, Xueguang,Ding, Weizhong,Lu, Xionggang
-
supporting information
p. 209 - 214
(2018/01/26)
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- Nitrogen-doped graphene-activated metallic nanoparticle-incorporated ordered mesoporous carbon nanocomposites for the hydrogenation of nitroarenes
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Herein, nanoscale metallic nanoparticle-incorporated ordered mesoporous carbon catalysts activated by nitrogen-doped graphene (NGr) were fabricated via an efficient multi-component co-assembly of a phenolic resin, nitrate, acetylacetone, the nitrogen-containing compound 1,10-phenanthroline, and Pluronic F127, followed by carbonization. The obtained well-dispersed nitrogen-doped graphene-activated transition metal nanocatalysts possess a 2-D hexagonally arranged pore structure with a high surface area (~500 m2 g-1) and uniform pore size (~4.0 nm) and show excellent activity for the selective hydrogenation-reduction of substituted nitroarenes to anilines in an environmentally friendly aqueous solution. The high catalytic performance and durability is attributed to the synergistic effects among the components, the unique structure of the nitrogen-doped graphene layer-coated metallic nanoparticles, and electronic activation of the doped nitrogen.
- Huang, Haigen,Wang, Xueguang,Sheng, Yao,Chen, Chenju,Zou, Xiujing,Shang, Xingfu,Lu, Xionggang
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p. 8898 - 8909
(2018/03/08)
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- N-doped graphitic carbon-improved Co-MoO3 catalysts on ordered mesoporous SBA-15 for chemoselective reduction of nitroarenes
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Metallic Co-MoO3 catalysts supported on ordered mesoporous SBA-15 were first prepared through in situ reaction of SBA-15-supported Co-Mo oxides with 1,10-phenanthroline. The resulting Co-MoO3/NC@SBA-15 catalysts with N-doped carbon (NC) exhibited high catalytic activity and chemoselectivity for selective reduction of various functionalized nitroarenes to the corresponding arylamines in ethanol with hydrazine hydrate at near room temperature (30 °C). For reduction of all tested substrates (28 examples), the catalyst could afford a conversion of >99% and arylamine selectivity of >99%. The excellent catalytic performance of the Co-MoO3/NC@SBA-15 was attributed to the Co-Nχ(C)-Mo active sites generated through the interaction between the surface Co-Nχ(C) and MoO3 species, promoting the dissociation of hydrazine molecule into the active H* species for the reduction of nitro groups. After the seventh cycle for reduction of 4-methoxylnitrobenzene, the 2%Co-MoO3/NC@SBA-15 showed little change in catalytic performance, textural properties, size and dispersion of metal species and valence states of elements, indicating high stability and recyclability.
- Huang, Haigen,Liang, Xiangcheng,Wang, Xueguang,Sheng, Yao,Chen, Chenju,Zou, Xiujing,Lu, Xionggang
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p. 127 - 137
(2018/05/04)
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- Polymer supported Nickel nanoparticles as recyclable catalyst for the reduction of nitroarenes to anilines in aqueous medium
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Polymer supported nickel nanoparticles, generated by calcination under nitrogen of a Ni(II) containing polyacrylamide, catalyzed the hydrogenation of nitroarenes to anilines in aqueous medium at room temperature in the presence of NaBH4. The protocol generally favored the formation of the desired aniline as single product in high yields with short reaction times and proved to be highly selective in the hydrogenation of halonitrobenzene to haloaniline, avoiding the formation of hydro-dehalogenated side-products. The catalyst displayed excellent recyclability over at least five cycles (which is not trivial for nickel nanoparticle based catalysts used in water) and no leaching of metal into solution occurred, that made the overall system eco-friendly and economic. STEM analyses revealed that the thermally formed Ni nanoparticles turned into cubic nanotwins under reaction conditions, which remained almost unchanged with the re-cycles.
- Romanazzi, Giuseppe,Fiore, Ambra Maria,Mali, Matilda,Rizzuti, Antonino,Leonelli, Cristina,Nacci, Angelo,Mastrorilli, Piero,Dell'Anna, Maria Michela
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- The synergic effects at the molecular level in CoS2 for selective hydrogenation of nitroarenes
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Catalytic functionalized aniline formation from nitroarenes is a core technology in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals. However, control of chemoselectivity still poses particular challenges with aromatic nitro substrates bearing one or more reducible groups. Here, we report the low-cost synthesis of a porous carbon supported CoS2 catalyst (CoS2/PC) and successfully apply the catalyst in the chemoselective hydrogenation of nitroarenes. For hydrogenation of 3-nitrostyrene, the catalyst furnishes a superior selectivity of 99% towards 3-aminostyrene at a conversion of >99%. Density functional theory calculations together with X-ray absorption fine structure spectroscopy reveal that terdentate and tetrahedral coordinated Co atoms in CoS2 (labeled as Co3 and Co4) are possible active sites. The face to face located Co3 and Co4 sites make the reaction rather local, and Co3 and Co4 sites are occupied by substrates and H2, respectively, which is beneficial to the superior activity and selectivity. The Co3-Co4 "synergic active site pair" in CoS2 makes the investigation of the synergic effects at the molecular level a reality on heterogeneous catalysts.
- Wei, Zhongzhe,Mao, Shanjun,Sun, Fanfei,Wang, Jing,Mei, Bingbao,Chen, Yiqing,Li, Haoran,Wang, Yong
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p. 671 - 679
(2018/02/14)
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- Highly chemoselective reduction of nitroarenes over non-noble metal nickel-molybdenum oxide catalysts
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The chemoselective reduction of nitroarenes is an important transformation for the production of arylamines, which are the primary intermediates in the synthesis of pharmaceuticals, agrochemicals and dyes. Heterogeneous non-noble metal nickel-molybdenum oxide catalysts supported on ordered mesoporous silica SBA-15 (Ni-MoO3/CN@SBA-15) were prepared for the first time by treating SBA-15-supported nickel-molybdenum oxide materials with 1,10-phenanthroline, and exhibited unprecedented catalytic activity and chemoselectivity for the reduction of various substituted nitroarenes to the corresponding aromatic amines in ethanol with hydrazine hydrate as a hydrogen donor under mild conditions owing to the synergistic effect of metal Ni and MoO3 species, affording excellent yields of >99% within very short reaction periods (≤60 min). The Ni-MoO3/CN@SBA-15 catalysts were highly stable and could easily be recovered by simple filtration or by an external magnetic field for at least ten recycling reactions without any observable loss of catalytic performance or leaching of metal components.
- Huang, Haigen,Wang, Xueguang,Li, Xu,Chen, Chenju,Zou, Xiujing,Ding, Weizhong,Lu, Xionggang
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p. 809 - 815
(2017/08/15)
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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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- High Performance and Active Sites of a Ceria-Supported Palladium Catalyst for Solvent-Free Chemoselective Hydrogenation of Nitroarenes
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Cerium oxide-supported palladium catalysts (Pd/CeO2) prepared by a simple impregnation method exhibit exciting catalytic activity and high chemoselectivity for the solvent-free hydrogenation of a variety of substituted nitroarenes including the reducible functional groups to the corresponding aromatic amines under mild reaction conditions. Taking nitrobenzene as an example, the Pd/CeO2 catalyst can afford aniline yields of >99 % with turnover frequencies as high as 11 411 h?1 and 69 824 h?1 at 40 °C and 100 °C, respectively. Pd2+ ion species exist as isolated single atoms with ?Pd2+?O2??Ce4+? linkages on the surface of PdxCe1?xO2?σ solid solution and are found to be active sites for the selective hydrogenation of nitroarenes in the absence of solvent. The superior catalytic performance can be attributed to the cooperative effect between Pd2+ ions and unique surface sites of CeO2. A possible mechanism is proposed for the hydrogenation of nitroarenes with H2 over the Pd/CeO2. The Pd/CeO2 catalyst can be recovered easily and reused for at least seven recycling reactions without loss of catalytic properties.
- Shi, Xiuxiu,Wang, Xueguang,Shang, Xingfu,Zou, Xiujing,Ding, Weizhong,Lu, Xionggang
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p. 3743 - 3751
(2017/10/16)
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- Co-based heterogeneous catalysts from well-defined Α-diimine complexes: Discussing the role of nitrogen
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Ar-BIANs and related α-diimine Co complexes were wet impregnated onto Vulcan XC 72 R carbon black powder and used as precursors for the synthesis of heterogeneous supported nanoscale catalysts by pyrolysis under argon at 800?°C. The catalytic materials feature a core-shell structure composed of metallic Co and Co oxides decorated with nitrogen-doped graphitic layers (NGr). These catalysts display high activity in the liquid phase hydrogenation of aromatic nitro compounds (110?°C, 50 bar H2) to give chemoselectively substituted aryl amines. The catalytic activity is closely related to the amount and type of nitrogen atoms in the final catalytic material, which suggests a heterolytic activation of dihydrogen.
- Formenti, Dario,Ferretti, Francesco,Topf, Christoph,Surkus, Annette-Enrica,Pohl, Marga-Martina,Radnik, J?rg,Schneider, Matthias,Junge, Kathrin,Beller, Matthias,Ragaini, Fabio
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- Catalytic Paper Spray Ionization Mass Spectrometry with Metal Nanotubes and the Detection of 2,4,6-Trinitrotoluene
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Materials are making inroads into mass spectrometry, and an example is the use of advanced materials for enhanced ionization by transformation of a less-ionizable molecule to an easily ionizable one. Here we show the use of Pt nanoparticle-decorated nanotubes as highly active catalysts for the reduction of 2,4,6-trinitrotoluene to 2,4,6-triaminotoluene and subsequent easy detection of the product by in situ ambient ionization mass spectrometry.
- Sarkar, Depanjan,Som, Anirban,Pradeep, Thalappil
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p. 11378 - 11382
(2019/03/26)
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- DNA interaction of bromomethyl-substituted acridines
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A series of acridines with bifunctional substituents was synthesized with the dual properties of DNA alkylation and intercalation. 4,5-Bis(bromomethyl)acridine (1) was previously reported to crosslink and intercalate with DNA. In this study, 1,8-bis(bromomethyl)acridine (2) and 2,7-bis(bromomethyl)acridine (3), monofunctional 2-(bromomethyl)-7-methylacridine (4) and 2,7-dimethylacridine (5) were synthesized, and their crosslinking and intercalative activities were investigated to assess the reactivity of bromomethyl acridines with DNA. Interstrand crosslinking activity was similar among the three bis(bromomethyl)acridines. The acridines exhibited intercalation activity for calf thymus DNA as follows: 3 > 4 > 2 = 1 5. Intracellular DNA-crosslinking and DNA-intercalating activities were evaluated using the Ames assay. 4 was mutagenic in Salmonella typhimurium TA100 and TA98, indicating that the bromomethyl group alkylated DNA bases. All three bis(bromomethyl)acridines were mutagenic in S. typhimurium TA92 and TA94, which can detect intracellular crosslinking DNA damage, whereas 5 was not mutagenic in these strains. The results showed that the bis(bromomethyl)acridines crosslinked DNA and intercalated between DNA bases, and 3 exhibited the highest crosslinking and intercalating activity.
- Harada, Kazuya,Imai, Takahiro,Kizu, Junko,Mochizuki, Masataka,Inami, Keiko
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p. 3375 - 3383
(2017/10/07)
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- Half-Sandwich Ruthenium Complexes with Schiff-Base Ligands: Syntheses, Characterization, and Catalytic Activities for the Reduction of Nitroarenes
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A series of ruthenium(II) p-cymene complexes containing Schiff-base ligands [Ru(p-cymene)LCl] [HL = pyridyl-salicylimine (2a-2d); HL = thiazol-salicylimine (2e-2h); HL = benzothiazol-salicylimine (2i-2l)] have been synthesized and characterized. All Schiff-base ligands and half-sandwich ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and infrared spectrometry. The molecular structures of ruthenium complexes 2b and 2k were further confirmed by single-crystal X-ray diffraction methods. Furthermore, these half-sandwich ruthenium complexes are active catalysts for the mild hydrogenation of nitroarenes to aromatic anilines in the presence of sodium tetrahydroborate reducing agent in water. The most efficient catalyst, 2b, was found be compatible with nitroarenes of various functional groups.
- Jia, Wei-Guo,Zhang, Hui,Zhang, Tai,Xie, Dong,Ling, Shuo,Sheng, En-Hong
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p. 503 - 512
(2016/03/01)
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- Synthesis, characterization and catalytic activity of gold complexes with pyridine-based selone ligands
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Three neutral pyridine-based selone compounds, 2,6-bis(1-methylimidazole-2-selone)pyridine (Bmsp), 2,6-bis(1-ethylimidazole-2-selone)pyridine (Besp) and 2,6-bis(1-isopropylimidazole- 2-selone)pyridine (Bpsp) have been synthesized and characterized. Reactions of HAuCl4 with pyridine-based selone ligands result in the formation of the complexes [Au(L)Cl2]+[AuCl2]- (L = Bmsp (1); L = Besp (2) and L = Bpsp (3)), respectively. All compounds have been characterized by elemental analysis, NMR IR spectra and electrospray ionization mass spectroscopic (ESI-MS). The molecular structure of 2 has been determined by X-ray crystallography. Moreover, the gold complexes are efficiently catalyzed nitroarenes reduction to aromatic amines in the presence of sodium tetrahydroborate reducing agent in water.
- Zhang, Hai-Ning,Jia, Wei-Guo,Xu, Qiu-Tong,Ji, Chang-Chun
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p. 315 - 320
(2016/07/06)
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- Solvent-Free Selective Hydrogenation of Nitroarenes Using Nanoclusters of Palladium Supported on Nitrogen-Doped Ordered Mesoporous Carbon
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The selective hydrogenation of nitroarenes is a key transformation for the production of aromatic amines, which are primary intermediates in the synthesis of pharmaceuticals, agrochemicals, and dyes. However, most reaction processes require toxic organic solvents and suffer from poor selectivity in the presence of other reducible groups. Herein, we report a successful example of nanoclusters of ultrafine Pd supported on N-modified ordered mesoporous CMK-3 carbon (Pd/N-CMK-3) prepared by a facile two-step impregnation route with aqueous solutions of 1,10-phenanthroline and H2PdCl4 that hydrogenated various nitroarenes highly efficiently and selectively to the corresponding aromatic amines with hydrogen in the absence of solvent. The Pd/N-CMK-3 catalyst could be recovered easily for multiple recycling reactions without a loss of catalytic performance.
- Huang, Haigen,Wang, Xueguang,Tan, Mingwu,Chen, Chenju,Zou, Xiujing,Ding, Weizhong,Lu, Xionggang
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p. 1485 - 1489
(2016/05/02)
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- Synthesis of Nickel Nanoparticles with N-Doped Graphene Shells for Catalytic Reduction Reactions
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The synthesis of novel nanoparticles is of general importance for the development of efficient heterogeneous catalysts. Herein, the preparation of carbon-supported nickel-based nanoparticles (NPs), modified by nitrogen-doped graphene layers, is reported for the first time. The resulting materials were characterized in detail by TEM, X-ray photoelectron spectroscopy (XPS), XRD, elemental analysis (EA), electron paramagnetic resonance (EPR), temperature-programmed reduction (TPR), BET, and Raman analysis. Initial catalytic tests revealed the potential of this class of compounds in hydrogenation reactions.
- Pisiewicz, Sabine,Formenti, Dario,Surkus, Annette-Enrica,Pohl, Marga-Martina,Radnik, J?rg,Junge, Kathrin,Topf, Christoph,Bachmann, Stephan,Scalone, Michelangelo,Beller, Matthias
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p. 129 - 134
(2016/01/25)
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- The low-pressure hydrogenation dinitrotoluence synthesizing tolylene diamine process and catalyst and process for the preparation of catalysts
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A process for synthesis of toluenediamine (TDA) by low pressure hydrogenation of dinitrotoluene (DNT) is as follows: preparing a fresh Raney nickel catalyst and DNT into fresh catalyst slurry, adding the fresh catalyst slurry into a hydrogenation reactor; respectively adding raw material DNT and hydrogen into the hydrogenation reactor for reaction, leading a liquid reaction product into a catalyst separator I for separation, sending an upper clear liquid to a catalyst separator II, sending a gas phase into a purge gas separator, and returning settled catalyst slurry to the hydrogenation reactor; and filtering a clear liquid in the central part of the catalyst separator II with a filter to obtain a crude TDA product. The process has the advantages of low equipment investment, low energy consumption, and synthesis of the toluenediamine (TDA) by hydrogenation of the dinitrotoluene in the absence of an externally added solvent and under the low pressure condition of 1MPa.
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Paragraph 0084-0086
(2017/03/08)
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- Facile assembly of nanosheet array-like CuMgAl-layered double hydroxide/rGO nanohybrids for highly efficient reduction of 4-nitrophenol
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A series of novel hierarchical nanosheet array-like hybrids xCu-LDH/rGO (xCu-LDH: CuxMg3?xAl-layered double hydroxide (x = 0.5, 1.0, and 1.5), rGO: reduced graphene oxide) were assembled via a facile and green aqueous-phase coprecipitation method. Systematic characterization suggests that the hybrids were constructed by hexagonal LDH nanoplates (~70 nm × 4.5 nm) interdigitated vertical to the surface of single-layer rGO. All the xCu-LDH/rGO hybrids exhibit a remarkable higher activity for catalytic reduction of 4-nitrophenol (4-NP) compared with pure Cu-LDH, commercial Pt/C and other recently reported Cu-related catalysts. These findings were carefully explained by deep study of the catalyst treated with NaBH4, and the xCu-LDH/rGO hybrids as a potential Cu2O reservoir were revealed for the first time. Typically for 1.0Cu-LDH/rGO, a part of Cu2+ ions on LDH layers were instantaneously in situ reduced to well-dispersed ultrafine Cu2O nanoparticles (~6.8 nm) by NaBH4 in an aqueous reduction system and thus formed relatively strong interaction between Cu2O and LDH/rGO greatly favoring enhanced activity for the reduction of 4-NP, other nitroarenes and organic dyes at room temperature. The excellent activity of the xCu-LDH/rGO hybrids can be attributed to the possible Cu2O-Cu-LDH-rGO three-phase synergistic effect, increased adsorption capacity for reactants via π-π stacking, and unique nanoarray-like morphology of the hybrids. Moreover, the 1.0Cu-LDH/rGO can be cycled for 20 runs without significant loss of activity, giving the hybrid long-term stability.
- Dou, Liguang,Zhang, Hui
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supporting information
p. 18990 - 19002
(2016/12/16)
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- Rapid and green reduction of aromatic/aliphatic nitro compounds to amines with NaBH4 and additive Ni2B in H2O
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Abstract NaBH4 with catalytic amounts of Ni2B as an additive reagent reduced aromatic and aliphatic nitro compounds to the corresponding amines in high to excellent yields. Reduction reactions were carried out in H2O within 3-30 min at room temperature or 75-80 °C. The catalytic activity of Ni2B as an additive reagent was superior to using the in situ precipitated one.
- Zeynizadeh, Behzad,Zabihzadeh, Mehdi
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p. 1221 - 1226
(2015/06/02)
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- USE OF THERMALLY-TREATED SUPPORTED COBALT CATALYSTS COMPRISING A POLYCYCLIC AROMATIC STRUCTURE CONSISTING OF NITROGEN LIGANDS FOR HYROGENATING AROMATIC NITRO COMPOUNDS
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The invention relates to the use of thermally-treated supported cobalt catalysts for hydrogenating aromatic nitro compounds, the cobalt catalysts having been prepared by in situ immobilization of a cobalt-amine complex on an inorganic porous support and subsequent pyrolysis, and, in the cobalt-amine complex used, cobalt being present bonded to an aromatic or heterocyclic nitrogen ligand L, the nitrogen ligand being selected so as to form a polyaromatic structure with the cobalt atom.
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Paragraph 0031; 0032
(2015/11/16)
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- In Situ-Generated Co0-Co3O4/N-Doped Carbon Nanotubes Hybrids as Efficient and Chemoselective Catalysts for Hydrogenation of Nitroarenes
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The earth-abundant nanohybrids Co0/Co3O4@N-doped carbon nanotubes were fabricated via an efficient thermal condensation of d-glucosamine hydrochloride, melamine, and Co(NO3)2·6H2O. The hybrids furnish excellent catalytic activity and perfect chemoselectivity (>99%) for a wide range of substituted nitroarenes (21 examples) under relatively mild conditions. The high catalytic performance and durability is attributed to the synergistic effects between each component, the unique structure of graphene layers-coated Co0, and the electronic activation of doped nitrogen. Density functional calculations indicate that the inner Co0 core and N species on the carbon shell can significantly decrease the dissociation energies of H2, giving evidence of the ability of carbon shell in the hybrids to enable H2 activation. These results open up an avenue to design more powerful low-cost catalysts for industrial applications.
- Wei, Zhongzhe,Wang, Jing,Mao, Shanjun,Su, Diefeng,Jin, Haiyan,Wang, Yihe,Xu, Fan,Li, Haoran,Wang, Yong
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p. 4783 - 4789
(2015/08/18)
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- Photochemically Engineering the Metal-Semiconductor Interface for Roomerature Transfer Hydrogenation of Nitroarenes with Formic Acid
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A mild photochemical approach was applied to construct highly coupled metal-semiconductor dyads, which were found to efficiently facilitate the hydrogenation of nitrobenzene. Aniline was produced in excellent yield (>99 %, TOF: 1183) using formic acid as hydrogen source and water as solvent at room temperature. This general and green catalytic process is applicable to a wide range of nitroarenes without the involvement of high-pressure gases or sacrificial additives. A mild photochemical approach was applied to construct highly coupled metal-semiconductor dyads (example in picture: carbon nitride), which were found to catalyze the hydrogenation of nitrobenzene. Aniline was produced in excellent yield (>99 %, TOF 1183) using formic acid as the hydrogen source and water as the solvent at room temperature. This process is applicable to many nitroarenes without the involvement of high-pressure gases or sacrificial additives.
- Li, Xin-Hao,Cai, Yi-Yu,Gong, Ling-Hong,Fu, Wei,Wang, Kai-Xue,Bao, Hong-Liang,Wei, Xiao,Chen, Jie-Sheng
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supporting information
p. 16732 - 16737
(2016/02/18)
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- Nanopalladium on amino-functionalized mesocellular foam as an efficient and recyclable catalyst for the selective transfer hydrogenation of nitroarenes to anilines
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Herein, we report on the use of nanopalladium on amino-functionalized siliceous mesocellular foam as an efficient heterogeneous catalyst for the transfer hydrogenation of nitroarenes to anilines. In all cases, the protocol proved to be highly selective and favored the formation of the desired aniline as the single product in high yields with short reaction times if naturally occurring and renewable γ-terpinene was employed as the hydrogen donor. Furthermore, the catalyst displayed excellent recyclability over five cycles and negligible leaching of metal into solution, which makes it an eco-friendly and economic catalyst to perform this transformation. The scalability of the protocol was demonstrated with the reduction of 4-nitroanisole on a 2 g scale, in which p-anisidine was isolated in 98 % yield. Copyright
- Verho, Oscar,Nagendiran, Anuja,Tai, Cheuk-Wai,Johnston, Eric V.,Baeckvall, Jan-E.
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p. 205 - 211
(2014/01/23)
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- Polymer supported palladium nanocrystals as efficient and recyclable catalyst for the reduction of nitroarenes to anilines under mild conditions in water
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Polymer supported palladium nanoparticles, generated in situ by Pd(II) reduction under reaction conditions, catalyzed the hydrogenation of nitroarenes to anilines with high efficiency in water at room temperature in the presence of NaBH4. The protocol proved to be highly selective and generally favored the formation of the desired aniline as single product in high yields with short reaction times. TEM analyses revealed that the size distribution of the formed Pd nanocrystals was regulated by the reductant agent. In details, when 1 atm H2 was used as the nitroarene reductant, the in situ generated polymer supported palladium nanoparticles were crystallites with diameters ranging from 6 to 10 nm. On the contrary, when the reaction was carried out in the presence of NaBH4 in water under N2 or air, the formation of Pd nanocrystallites was observed as well, but this time they were smaller (mean size diameter ca. 3 nm) and catalytically more active compared to the palladium nanoparticles formed under 1 atm H2 in the absence of NaBH4. The catalyst displayed excellent recyclability over twelve cycles and no leaching of metal into solution occurred, which made the overall system eco-friendly and economic.
- Dell'Anna, Maria Michela,Intini, Simona,Romanazzi, Giuseppe,Rizzuti, Antonino,Leonelli, Cristina,Piccinni, Ferruccio,Mastrorilli, Piero
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p. 307 - 314
(2014/12/10)
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- One pot catalytic NO2 reduction, ring hydrogenation, and N-alkylation from nitroarenes to generate alicyclic amines using Ru/C-NaNO 2
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A report to produce alicyclic amines and subsequent N-alkylation with alcohols using Ru/C-NaNO2 catalyzed facile transformation of nitrobenzene was investigated. Effects of solvent, temperature, pressure, reaction time, and molar-ratio of substrate/catalyst on product composition were also studied. These mechanistic studies explain that nitrobenzene undergoes hydrogenation reaction in the following order; -NO2 reduction to -NH2, aromatic ring-hydrogenation to alicyclic, and from the reaction of alcohol to give N-alkylated amines. This investigation shed lights on possible application to polyurethane chemistry since these amines are used as important precursors for diisocyanates.
- Oh, Seung Geun,Mishra, Vivek,Cho, Jin Ku,Kim, Baek-Jin,Kim, Hoon Sik,Suh, Young-Woong,Lee, Hyunjoo,Park, Ho Seok,Kim, Yong Jin
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- Catalytic hydrogenation of nitrophenols and nitrotoluenes over a palladium/graphene nanocomposite
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We report a stable palladium/graphene (Pd/G) nanocomposite with differing Pd content for use in the catalytic hydrogenation of nitrophenols and nitrotoluenes. Various microscopic and spectroscopic techniques were employed to characterize the as-prepared catalysts. Catalytic hydrogenation reactions of nitrophenols were conducted in aqueous solution by adding NaBH4, while the nitrotoluene hydrogenation was carried out in methanol in the presence of H2 because of the poor solubility in water. The Pd/G hybrids exhibited much higher activity and higher stability than the commercial Pd/C. Due to the presence of a large excess of NaBH4 compared to p-nitrophenol, the kinetic data can be explained by the assumption of a pseudo-first-order reaction with regard to p-nitrophenol. The resulting high catalytic activity can be attributed to the graphene sheets' strong dispersion effect for Pd nanoparticles and good adsorption ability for nitrobenzene derivatives via π-π stacking interactions. A plausible mechanism is proposed. Considering inductive and conjugation effects that may affect the reactions, the reactivity of nitrophenols in this study is expected to follow the order m-NP > o-NP > p-NP > 2,4-DNP > 2,4,6-TNP, which is in good agreement with the experimental results. This journal is the Partner Organisations 2014.
- Sun, Jingwen,Fu, Yongsheng,He, Guangyu,Sun, Xiaoqiang,Wang, Xin
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p. 1742 - 1748
(2014/06/09)
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- Palladium nanoparticles supported on nitrogen-functionalized active carbon: A stable and highly efficient catalyst for the selective hydrogenation of nitroarenes
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Nitrogen-functionalized active carbon-supported ultrasmall Pd nanoparticles were conveniently prepared by using a postloading method. The Pd catalyst was highly active and selective for the hydrogenation of nitroarenes at room temperature under ambient pressure. Reducible groups such as ketone, carboxylic acid, and ester were not hydrogenated, and the corresponding anilines were obtained quantitatively. The Pd catalyst demonstrated high stability and could be reused 10 times without the loss of catalytic performance. Be active, be fit! A facile method to prepare nitrogen-functionalized active carbon (NAC) has been described. The small-sized Pd nanoparticles are supported on NAC by using a postloading method. The representative catalyst Pd@NAC-800 demonstrated high activity and selectivity for the selective hydrogenation of nitroarenes under mild reaction conditions.
- Li, Zelong,Li, Jinlei,Liu, Jianhua,Zhao, Zelun,Xia, Chungu,Li, Fuwei
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p. 1333 - 1339
(2014/05/20)
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- Metallic nanoparticles immobilized in magnetic metal-organic frameworks: Preparation and application as highly active, magnetically isolable and reusable catalysts
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Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this paper, ultrafine noble metallic nanoparticles are incorporated into cauliflower-like porous magnetic metal-organic frameworks (MOFs). With the restriction effects of the pore/surface structure in the MOFs, "surfactant-free" metallic nanoparticles are successfully obtained on a 2-3 nm scale. In addition, both the thickness of MOFs shell and the content of noble metallic NPs are tunable on the MOFs coating. Moreover, the microspheres exhibit excellent performance for the catalytic reduction of p-nitrophenol with a turnover frequency of 3094 h-1. The uniform cavities in the MOFs shell provide docking sites for p-nitrophenol and act as confinement nanoreactors, which greatly improves the catalytic performance. Most importantly, the magnetically responsive microspheres can be easily recovered by a magnetic field and show excellent reusability. The as-prepared catalyst also shows good activity for the reduction of other nitrobenzenes. Consequently, this work provides a highly active, magnetically isolable, and recyclable catalyst, which can be used for various catalytic industrial processes. The fundamental model can be further employed in a variety of biomedical fields including drug delivery and biological molecules separation. the Partner Organisations 2014.
- Zhang, Hai-Juan,Qi, Sheng-Da,Niu, Xiao-Ying,Hu, Jing,Ren, Cui-Ling,Chen, Hong-Li,Chen, Xing-Guo
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p. 3013 - 3024
(2014/08/18)
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- Selective reduction of halogenated nitroarenes with hydrazine hydrate in the presence of Pd/C
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A large variety of halogenated nitroarenes have been selectively reduced with hydrazine hydrate in the presence of Pd/C to give the corresponding (halogenated) anilines in good yield.
- Li, Fang,Frett, Brendan,Li, Hong-Yu
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p. 1403 - 1408
(2014/06/23)
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- Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes
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Molecularly well-defined homogeneous catalysts are known for a wide variety of chemical transformations. The effect of small changes in molecular structure can be studied in detail and used to optimize many processes. However, many industrial processes require heterogeneous catalysts because of their stability, ease of separation and recyclability, but these are more difficult to control on a molecular level. Here, we describe the conversion of homogeneous cobalt complexes into heterogeneous cobalt oxide catalysts via immobilization and pyrolysis on activated carbon. The catalysts thus produced are useful for the industrially important reduction of nitroarenes to anilines. The ligand indirectly controls the selectivity and activity of the recyclable catalyst and catalyst optimization can be performed at the level of the solution-phase precursor before conversion into the active heterogeneous catalyst.
- Westerhaus, Felix A.,Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Pohl, Marga-Martina,Radnik, Joerg,Surkus, Annette-Enrica,Rabeah, Jabor,Junge, Kathrin,Junge, Henrik,Nielsen, Martin,Brueckner, Angelika,Beller, Matthias
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p. 537 - 543
(2013/07/19)
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- Functionally substituted Schiff bases in reduction reactions
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Functionally substituted Schiff bases obtained by the condensation of nitroaniline, pyrimidinylaminoaniline, 5-aminoquinoline, 5-aminoquinaldine derivatives with 4-methylformylbenzoate were studied in the reactions of sodium borohydride with acidic activators, hydrazine hydrate in the presence of Raney nickel, Raney alloy in the presence of potassium hydroxide. By the reduction of azomethines new benzyl derivatives of aniline, quinolylamine, arylaminopyrimidine, and phenylenediamine were obtained.
- Koroleva,Gusak,Ignatovich,Ermolinskaya
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p. 212 - 220
(2013/07/25)
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- METHOD FOR TREATMENT OF ISOCYANATE RESIDUE, AND METHOD FOR TREATMENT OF CARBONATE
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A method for treating an isocyanate residue, which comprises carrying out a thermal decomposition reaction of a carbamate that is produced by the reaction among an amine, urea and/or an N-unsubstituted carbamic acid ester and an alcohol to produce a decomposition solution, separating an isocyanate and the alcohol from the decomposition solution to produce the isocyanate residue, and bringing the isocyanate residue into contact with high-pressure/high-temperature water to decompose the isocyanate residue into an amine; and a method for treating a carbonate, which comprises bringing the carbonate into contact with high-pressure/high-temperature water to decompose the carbonate into an alcohol.
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Page/Page column 24
(2012/11/07)
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- Chemoselective transfer hydrogenation to nitroarenes mediated by cubane-type Mo3S4 cluster catalysts
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Chemoselective cubes: Cubane-type [Mo3S4X 3(dmpe)3]+ clusters (dmpe=1,2-(bis) dimethylphosphinoethane), in combination with an azeotropic 5:2 mixture of HCOOH and NEt3 as the reducing agent, act as selective cluster catalysts (X=H) or precatalysts (X=Cl) for the transfer hydrogenation of functionalized nitroarenes, without the formation of hazardous hydroxylamines. Copyright
- Sorribes, Iván,Wienh?fer, Gerrit,Vicent, Cristian,Junge, Kathrin,Llusar, Rosa,Beller, Matthias
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experimental part
p. 7794 - 7798
(2012/10/08)
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- Rapid hydrogenation of aromatic nitro compounds in supercritical carbon dioxide: Mechanistic implications via experimental and theoretical investigations
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An exceptionally rapid hydrogenation of nitrobenzene to aniline [TOF=252,000 h-1] over palladium containing MCM-41 (Pd/MCM-41) with excellent yield of >99% can be achieved in supercritical carbon dioxide at 50 °C and a hydrogen pressure of 2.5 MPa. It has been observed that this promising method preferred a single phase between liquid substrate and carbon dioxide-hydrogen system. The ascendancy of the supercritical carbon dioxide medium is established in comparison with the conventional organic solvent and solvent-less conditions. Changes in the reaction parameters such as carbon dioxide and hydrogen pressure, temperature and the reaction time do not affect the selectivity. A combined experimental and theoretical study has elucidated the mechanism under the studied reaction condition because experimental observations revealed a direct conversion of nitrobenzene to aniline. However, density functional theory (DFT) calculation shows that the direct conversion is energetically unfavourable; hence, a stepwise mechanism has been proposed. Theoretical predictions and experimental observations suggested that the rate-limiting step of nitrobenzene conversion is different from that of the liquid phase hydrogenation. This catalytic process can also be successfully extended to the hydrogenation of other aromatic nitro compounds with different substituents. Easy separation of the liquid product from catalyst and the use of an environmentally friendly solvent make this procedure a viable and an attractive green chemical process. Copyright
- Chatterjee, Maya,Chatterjee, Abhijit,Kawanami, Hajime,Ishizaka, Takayuki,Suzuki, Toshishige,Suzuki, Akira
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experimental part
p. 2009 - 2018
(2012/09/22)
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- General and selective iron-catalyzed transfer hydrogenation of nitroarenes without base
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The first well-defined iron-based catalyst system for the reduction of nitroarenes to anilines has been developed applying formic acid as reducing agent. A broad range of substrates including other reducible functional groups were converted to the corresponding anilines in good to excellent yields at mild conditions. Notably, the process constitutes a rare example of base-free transfer hydrogenations.
- Wienhoefer, Gerrit,Sorribes, Ivan,Boddien, Albert,Westerhaus, Felix,Junge, Kathrin,Junge, Henrik,Llusar, Rosa,Beller, Matthias
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experimental part
p. 12875 - 12879
(2011/10/03)
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- Efficient and highly selective iron-catalyzed reduction of nitroarenes
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Pyrolysis of iron-phenanthroline complexes supported on carbon leads to highly selective catalysts for the reduction of structurally diverse nitroarenes to anilines in 90-99% yields. Excellent chemoselectivity for the nitro group reduction is demonstrated.
- Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Westerhaus, Felix A.,Surkus, Annette-Enrica,Pohl, Marga-Martina,Junge, Henrik,Junge, Kathrin,Beller, Matthias
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supporting information; experimental part
p. 10972 - 10974
(2011/10/31)
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- Convenient reduction of nitro compounds to their corresponding amines with promotion of NaBH4/Ni(OAc)2.4H2O system in wet CH3CN
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NaBH4 in the presence of catalytic amounts of Ni(OAc) 2.4H2O reduces varieties of nitro compounds to their corresponding amines. Reduction reactions were carried out in a mixture of CH3CN and H2O (3.0:0.3 ml) at room temperature with high to excellent yields of products.
- Setamdideh, Davood,Khezri, Behrooz,Mollapour, Manouchehr
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experimental part
p. 991 - 996
(2012/03/27)
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