- Highly Efficient Photo-Reduction of p-Nitrophenol by Protonated Graphitic Carbon Nitride Nanosheets
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Photocatalytic reduction of p-nitrophenol to p-aminophenol is important because of the high toxicity of p-nitrophenol and the wide application of p-aminophenol. Graphitic carbon nitride (g-CN) is an excellent photocatalyst for various photo-reduction reac
- Qian, Jiajia,Yuan, Aili,Yao, Chengkai,Liu, Jiyang,Li, Benxia,Xi, Fengna,Dong, Xiaoping
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- Pd@tetrahedral hollow magnetic nanoparticles coated with N-doped porous carbon as an efficient catalyst for hydrogenation of nitroarenes
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Hollow magnetic nanoparticles (MNPs) with tetrahedral morphology were synthesized and then covered by a shell prepared by coating with melamine–formaldehyde followed by the introduction of glucose-derived carbon. Subsequently, Pd nanoparticles were immobi
- Sadjadi, Samahe,Heravi, Majid M.
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- Composite of β-cyclodextrin and bentonite clay: a promising support for Pd immobilization and developing a catalyst for hydrogenation of nitroarenes under mild reaction condition
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In attempt to take advantages of naturally occurring compounds for the catalysis, a novel composite composed of β-cyclodextrin, dendrimer and bentonite clay is fabricated and utilized as a support for the stabilization of Pd nanoparticles. To prepare the support, bentonite is amino functionalized and then successively reacted with 2,4,6-trichloro-1,3,5-triazine and ethylenediamine to furnish a dendrimer of generation II on bentonite. Afterwards, the terminal functionalities of the dendrimer were adorned with cyclodextrin. Bentonite played role in the heterogenation of the catalyst and improvement of the stability of the composite while, cyclodextrins served as molecular shuttles and capping agent for the as-prepared Pd nanoparticles. Dendrimer with multi nitrogen atoms, on the other hand, improved Pd anchoring through electrostatic interactions. The catalyst was applied for the hydrogenation of nitroarenes under mild reaction condition in aqueous media in a selective manner. Notably, the catalyst could be recovered and reused repeatedly.
- Koohestani, Fatemeh,Sadjadi, Samahe
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- Chemoselective hydrogenation of halonitroaromatics over γ-Fe 2O3-supported platinum nanoparticles: The role of the support on their catalytic activity and selectivity
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Solvated platinum atoms, obtained by metal vapour synthesis (MVS), were conveniently used to prepare γ-iron oxide and γ-alumina supported Pt catalysts containing small metal nanoparticles of controlled size, ranging 0.5-3.0 nm in diameter (HR-TEM). The γ-Fe2O3- supported Pt system showed higher catalytic activity and selectivity than those of a similarly prepared γ-Al2O3-supported system in the selective hydrogenation reactions of p- and o-chloronitrobenzene to the corresponding haloanilines, in mild reaction conditions (25°C, 0.1 MPa hydrogen pressure) (p-chloronitrobenzene: specific activity (SA) = 59.5 min -1, Selectivity (Sel.) = 99.9%; o-chloronitrobenzene: SA = 42.8 min-1, Sel. = 99.2%). The Pt/γ-Fe2O3 system also showed high catalytic efficiency (Sel. > 98%, at 100% of conversion) in the selective hydrogenations of m-chloro-, p- and o-bromo- and p- and o-iodonitrobenzenes. XPS structural studies performed on a pristine Pt/γ-Fe2O3 sample as well as on a sample recovered after the reaction, indicate that the catalytic process did not induce permanent modification in the chemical and/or electronic structure of the catalyst according with the high reusability of the system.
- Evangelisti, Claudio,Aronica, Laura Antonella,Botavina, Maria,Martra, Gianmario,Battocchio, Chiara,Polzonetti, Giovanni
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- Pd stabilized on nanocomposite of halloysite and β-cyclodextrin derived carbon: An efficient catalyst for hydrogenation of nitroarene
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Carbon nanospheres, CCDs, were fabricated using β-cyclodextrin as carbon precursor. The as prepared CCD was then hybridized with halloysite nanotubes (Hal) through hydrothermal treatment to furnish a nanocomposite, Hal-CCD that was subsequently applied as
- Sadjadi, Samahe,Ghoreyshi Kahangi, Fatemeh,Heravi, Majid M.
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- Palladated composite of Cu-BDC MOF and perlite as an efficient catalyst for hydrogenation of nitroarenes
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A novel composite of metal-organic framework and perlite is prepared through hydrothermal treatment of terephthalic acid and Cu(NO3)2·3H2O in the presence of perlite. The resulting composite was then utilized as a support for the immobilization of Pd nanoparticles. The obtained compound was characterized via XRD, TGA, ICP, FTIR, TEM, FE-SEM/EDS and elemental mapping analysis and applied as a catalyst for the hydrogenation of nitroarenes under mild reaction condition. The results approved that the catalyst could efficiently promote hydrogenation of various nitroarenes with different electronic densities and steric properties. Moreover, the catalyst showed high selectivity towards hydrogenation of nitro groups. Hot filtration test affirmed heterogeneous nature of catalysis. Furthermore, the present catalytic composite was highly recyclable with low Pd leaching. A comparative study also approved superior activity of the composite compared to palladated perlite and metal-organic framework.
- Koohestani, Fatemeh,Sadjadi, Samahe
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- Industrial Cunninghamia lanceolata carbon supported FeO(OH) nanoparticles-catalyzed hydrogenation of nitroarenes
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The development of green and efficient methods for hydrogenation of nitroarenes is still highly demanding in organic synthesis. Herein, we report an industrial Cunninghamia lanceolata carbon supported FeO(OH) nanoparticles process for the synthesis of aryl amines with good yields via hydrogenation of nitroarenes. Nine key anti-cancer drug intermediates were successfully achieved with protocol. And Osimertinib intermediate 4m can be smoothly synthesized at a 2.67 kg-scale with >99.5% HPLC purity. This protocol features cheap carbon source, highly catalytic activity, simple operation, kilogram-scalable and recyclable catalysts (eight times without observable losing activity).
- Fu, Lihua,Li, Dingzhong,Lu, Hao,Qiu, Renhua,Sun, Tulai,Xing, Chen,Yang, Tianbao
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- Selective hydrodeoxygenation of acetophenone derivatives using a Fe25Ru75@SILP catalyst: a practical approach to the synthesis of alkyl phenols and anilines
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A versatile synthetic pathway for the production of valuable alkyl phenols and anilines has been developed based on the selective hydrodeoxygenation of a wide range of hydroxy-, amino-, and nitro-acetophenone derivatives as readily available substrates. Bimetallic iron ruthenium nanoparticles immobilized on an imidazolium-based supported ionic liquid phase (Fe25Ru75@SILP) act as highly active and selective catalysts for the deoxygenation of the side-chain without hydrogenation of the aromatic ring. The catalytic system allows operation under continuous flow conditions with high robustness and flexibility as demonstrated for the alternating conversion of 3′,5′-dimethoxy-4′-hydroxyacetophenone and 4′-hydroxynonanophenone as model substrates.
- Bordet, Alexis,Goclik, Lisa,Leitner, Walter,Walschus, Henrik
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supporting information
p. 2937 - 2945
(2022/04/07)
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- In situcreation of multi-metallic species inside porous silicate materials with tunable catalytic properties
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Porous metal silicate (PMS) material PMS-11, consisting of uniformly distributed multi-metallic species inside the pores, is synthesized by using a discrete multi-metal coordination complex as the template, demonstrating high catalytic activity and selectivity in hydrogenation of halogenated nitrobenzenes by synergistically activating different reactant moleculesviaNi and Co transition metal centers, while GdIIILewis acid sites play a role in tuning the catalytic properties.
- Liu, Yang-Yang,Wu, Chuan-De,Zhan, Guo-Peng
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supporting information
p. 6185 - 6188
(2021/06/30)
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- A suitable modified palladium immobilized on imidazolium supported ionic liquid catalysed transfer hydrogenation of nitroarenes
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The first well-defined modified palladium immobilized on imidazolium supported ionic liquid catalyst has been developed for the transfer hydrogenation of nitroarenes to anilines in good to excellent yields with formic acid as reducing agent. This methodology applies eco-friendly a reducing agent which is non-toxic, water soluble, more stable and simpler to handle. Particularly, the process constitutes a rare model of base-free transfer hydrogenations. The catalyst was reused up to nine consecutive cycles without any significance loss in its activity.
- Atheeswari, Alagudurai,Kanimozhi, Nallusamy,Karthikeyan, Parasuraman,Shanmugapriya, Ramasamy
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- Palladated composite of MOF and cyclodextrin nanosponge: A novel catalyst for hydrogenation reaction
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In attempt to develop green protocols for organic transformations, a novel catalyst is prepared by combination of the features of metal-organic frameworks and polymers of cyclic carbohydrates. In detail, cyclodextrin nanosponge was synthesized from β-cycl
- Koohestani, Fatemeh,Sadjadi, Samahe
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- Cu-Catalyzed Cross-Coupling of Nitroarenes with Aryl Boronic Acids to Construct Diarylamines
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The development and study of a simple copper-catalyzed reaction of nitroarenes with aryl boronic acids to form diarylamines that uses phenyl silane as the stoichiometric terminal reductant is described. This cross-coupling reaction requires as little as 2 mol % of CuX and 4 mol % of diphosphine for success and tolerates a broad range of functional groups on either the nitroarene or the aryl boronic acid to afford the amine in good yield. Mechanistic investigations established that the cross-coupling reaction proceeds via a nitrosoarene intermediate and that copper is required to catalyze both the deoxygenation of the nitroarene to afford the nitrosoarene and C-NAr bond formation of the nitrosoarene with the aryl boronic acid.
- Guan, Xinyu,Zhu, Haoran,Driver, Tom G.
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p. 12417 - 12422
(2021/10/12)
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- Method for synthesizing heteroatom- substituted aromatic compound from styrene compound
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The invention discloses a method for synthesizing a heteroatom-substituted aromatic compound from a styrene compound, which comprises the following steps of: mixing a styrene compound with a general formula (I) and a heteroatom-containing compound with a general formula (II), and reacting in the presence of an acid additive and an organic solvent to obtain a heteroatom-substituted compound with ageneral formula (III). According to the synthesis method disclosed by the invention, a large amount of styrene compounds are used as raw materials and react to generate aromatic amine or phenol compounds under the action of no metal catalysis; and compared with the traditional aromatic amine and phenol synthesis method, the method has the advantages of high yield, simple conditions, low waste discharge amount, no metal participation, simple reaction equipment, easiness in industrial production and the like.
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Paragraph 0189-0192
(2021/02/06)
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- Selective Thiocyanation and Aromatic Amination to Achieve Organized Annulation of Enaminone with Thiocyanate
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A tandem insertion of thiocyanate to enamine was performed for the regioselective synthesis of multisubstituted benzoimidazo[2,1-b]thiazoles. This method was shown to be effective in addressing the issue of isomerization encountered in common strategies. With a change made to the leading group on the aniline fragment of enamine, the reaction achieved different transformations, thus enabling multisubstituted benzo[4,5]imidazo[2,1-b]thiazoles and thiazoles in satisfactory yields.
- Feng, Xukai,Leng, Xin,Li, Jianli,Li, Yao,Liu, Hua,Liu, Lang,Liu, Ping,She, Mengyao,Zhang, Jun,Zhang, Shengyong,Zheng, Tingting
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supporting information
p. 8396 - 8401
(2021/11/17)
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- Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides
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A Lewis base catalyst Trip-SMe (Trip = triptycenyl) for electrophilic aromatic halogenation using N-halosuccinimides (NXS) is introduced. In the presence of an appropriate activator (as a noncoordinating-anion source), a series of unactivated aromatic compounds were halogenated at ambient temperature using NXS. This catalytic system was applicable to transformations that are currently unachievable except for the use of Br2 or Cl2: e.g., multihalogenation of naphthalene, regioselective bromination of BINOL, etc. Controlled experiments revealed that the triptycenyl substituent exerts a crucial role for the catalytic activity, and kinetic experiments implied the occurrence of a sulfonium salt [Trip-S(Me)Br][SbF6] as an active species. Compared to simple dialkyl sulfides, Trip-SMe exhibited a significant charge-separated ion pair character within the halonium complex whose structural information was obtained by the single-crystal X-ray analysis. A preliminary computational study disclosed that the πsystem of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.
- Nishii, Yuji,Ikeda, Mitsuhiro,Hayashi, Yoshihiro,Kawauchi, Susumu,Miura, Masahiro
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supporting information
p. 1621 - 1629
(2020/02/04)
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- Palladium Nanocatalysts Encapsulated on Porous Silica @ Magnetic Carbon-Coated Cobalt Nanoparticles for Sustainable Hydrogenation of Nitroarenes, Alkenes and Alkynes.
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Palladium nanoparticles were impregnated on porous silica shell carbon-coated cobalt nanoparticles, resulting in a magnetically retrievable material that was evaluated in the catalytic hydrogenation of nitroarenes, alkenes and alkynes. The prepared material was characterized by HR-XRD, HR-TEM, elemental mapping EDX, ICP-OES and XPS analyses, revealing highly dispersed palladium nanoparticles within the porous platform that could account for the high activity observed. Mild reaction conditions, easy retrievability of the catalyst with the aid of an external magnet, recycling in four runs with a total leaching of 19 ppm (1.2 % of the initially employed Pd amount), and high stability makes this material attractive for sustainable and environmentally benign applications.
- Purohit, Gunjan,Rawat, Diwan S.,Reiser, Oliver
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p. 569 - 575
(2019/11/19)
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- CO-free, aqueous mediated, instant and selective reduction of nitrobenzeneviarobustly stable chalcogen stabilised iron carbonyl clusters (Fe3E2(CO)9, E = S, Se, Te)
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Highly stable and thermally robust iron chalcogenide carbonyl clusters Fe3E2(CO)9(E = S, Se or Te) have been explored for the reduction of nitrobenzene. A 15 min thermal heating of an aqueous solution of nitrobenzene and hydrazine hydrate in the catalytic presence of Fe3E2(CO)9(E = S, Se or Te) clusters yield average to excellent aniline transformations. Among the S, Se and Te based iron chalcogenised carbonyl clusters, the diselenide cluster was found to be most efficient and produce almost 90% yield of the desired amino product, the disulfide cluster was also found to be significantly active, produce the 85% yield of amino product, while the ditelluride cluster was not found to be active and produced only 49% yield of the desired product. The catalyst can be reused up to three catalytic cycles and it needs to be dried in an oven for one hour prior to reuse for the best results. The developed method is inexpensive, environmentally benign, does not require any precious metal or a high pressure of toxic CO gas and exclusively brings the selective reduction of the nitro group under feasible and inert free conditions.
- Joshi, Raj Kumar,Kumari, Sangeeta,Sharma, Charu,Soni, Aditi,Srivastava, Avinash Kumar
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p. 32516 - 32521
(2020/09/17)
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- In situ-formed cobalt embedded into N-doped carbon as highly efficient and selective catalysts for the hydrogenation of halogenated nitrobenzenes under mild conditions
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Inhibiting the dehalogenation is the main challenge when halogenated nitrobenzenes are hydrogenated using H2 as hydrogen source by heterogeneous catalysis. Herein, the earth-abundant cobalt embedded into N-doped carbon (Co@CN) catalysts were fabricated via one-pot pyrolysis of tannic acid, Co(NO3)2·6H2O and melamine, which can function as a highly efficient non-noble-metal-based heterogeneous catalyst for selective hydrogenation of halogenated nitrobenzenes. Chloroanilines, bromoanilines, and iodoanilines, including all regioisomers, could be obtained with excellent selectivity (typically >99 %) at 60 °C under 1 MPa H2, at almost complete conversion of the substrates. Additionally, Co@CN demonstrated excellent catalytic stability and could be reused at least five times without obvious loss of catalytic activity and selectivity. Therefore, the Co@CN catalyst exhibits vast potential for future industrial application in the selective hydrogenation of halogenated nitrobenzenes.
- Cao, Yueling,Liu, Kangkai,Wu, Chen,Zhang, Hepeng,Zhang, Qiuyu
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- N,S co-doped hierarchically porous carbon materials for efficient metal-free catalysis
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Metal-free carbon catalysts with excellent catalytic performance have drawn much research attention recently. Herein, polymer-derived N,S co-doped carbon catalysts (PDNSC-X) with a hierarchically porous structure were facilely prepared by a cost-effective and convenient strategy via carbonization of a N- and S atom-containing polymer precursor and were subsequently used as efficient metal-free catalysts. The catalytic activity of the as-fabricated PDNSC-800 was greater than those of other reported heteroatom-doped carbon catalysts in catalytic reduction of various nitroarenes. The high catalytic activity of PDNSC-800 was related to the synergistic effects of a high surface area, a hierarchically porous structure, abundant N- and S-containing active sites, and defect formation. In addition, the close relationship between the N species (especially pyrrolic N) and high selectivity in metal-free catalytic synthesis was investigated in the reduction of nitroarenes and selective oxidation of ethylbenzene. This study may provide a new strategy to fabricate specific heteroatom-doped metal-free carbon catalysts for environmentally friendly efficient organic transformation.
- Hu, Xiwei,Sun, Xun,Song, Qiang,Zhu, Yangyang,Long, Yu,Dong, Zhengping
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supporting information
p. 742 - 752
(2020/02/21)
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- 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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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Nitromethane as a reagent for the synthesis of 3-nitroindoles from 2-haloarylamine derivatives
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A new approach to the synthesis of 3-nitroindoles using palladium-catalyzed arylation of nitromethane with N-(2-bromoaryl)imidates was developed. A convenient and rapid method for cyclization of ethyl N-(2-nitromethylaryl)acetimidates to 2-methyl-3-nitro-1H-indoles was proposed.
- Chesnokov,Ageshina,Maryanova,Rzhevskiy,Gribanov,Topchiy,Nechaev,Asachenko
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p. 2370 - 2377
(2020/12/31)
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- PRODUCTION METHOD OF PRIMARY AMINE COMPOUND
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PROBLEM TO BE SOLVED: To provide a simple production method of a primary amine compound unnecessary for complicated procedures and toxic sodium azide or the like. SOLUTION: A production method of a primary amine compound includes a step for reacting a ketone compound and an oxime compound in the presence of alcohol and an acid catalyst. Preferably, the acid catalyst is hydrochloric acid, sulfuric acid, methanesulfonic acid, camphorsulfonic acid, a tosyl acid hydrate, trifluoromethane sulfonic acid or a boron trifluoride diethyl ether complex. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0029
(2019/09/20)
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- AN IMPROVED ONE POT, ONE STEP PROCESS FOR THE HALOGENATION OF AROMATICS USING SOLID ACID CATALYSTS
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The present invention disclosed an improved one pot, one step process for halogenation of compound of formula (II) to afford corresponding halogenated compound of formula (I) having improved yield and increased selectivity under very mild conditions.
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Page/Page column 0063
(2019/04/18)
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- Hydrogenation of Functionalized Nitroarenes Catalyzed by Single-Phase Pyrite FeS2 Nanoparticles on N,S-Codoped Porous Carbon
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Catalytic hydrogenation of nitroarenes is an industrially very important and environmentally friendly process for the production of anilines; however, highly chemoselective reduction of nitroarenes decorated with one or more reducible groups in a nitroarene molecule remains a challenge. Herein, a novel hybrid non-noble iron-based nanocatalyst (named as FeS2/NSC) was developed, which was prepared from biomass as C and N source together with inexpensive Fe(NO3)3 as Fe source through high-temperature pyrolysis in a straightforward and cost-effective procedure. Comprehensive characterization revealed that single-phase pyrite FeS2 nanoparticles with precisely defined composition and uniform size were homogeneously dispersed on N,S-codoped porous carbon with large specific surface area, hierarchical porous channels, and high pore volume. The resultant catalyst FeS2/NSC demonstrated good catalytic activity for hydrogenation of functionalized nitroarenes with good tolerance of various functional groups in water as a sustainable and green solvent. Compared with bulk pyrite FeS2 and other non-noble metal-based heterogeneous catalysts reported in the literature, a remarkably enhanced activity was observed under mild reaction conditions. More importantly, FeS2/NSC displayed exclusive chemoselectivity for the reduction of nitro groups for nitroarenes bearing varying readily reducible groups.
- Duan, Yanan,Dong, Xiaosu,Song, Tao,Wang, Zhaozhan,Xiao, Jianliang,Yuan, Youzhu,Yang, Yong
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- Highly efficient MoIV3 ?sbIII cluster frustrated Lewis pair hydrogenation
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Frustrated Lewis pairs (FLPs) featuring Lewis acid-base synergistic action have been recognized as one of the most powerful bifunctional catalytic systems. Each Lewis component, however, is usually composed of a single atom and hence lacks a cooperative e
- Yu, Fang,Xu, Li
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p. 17445 - 17450
(2019/12/23)
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- Electronic Modulation of Palladium in Metal Phosphide Nanoparticles for Chemoselective Reduction of Halogenated Nitrobenzenes
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Tuning the electronic property of a transition metal plays an important role in the selective catalysis. Herein, the control synthesis of (PdxNiy)-P nanoparticles is reported. The binding energy of Pd3d5/2 as a function of
- Zhao, Ming,Feng, Baoming,Qiao, Xiaofei,Zhong, Ning,Ge, Xuemei,Ji, Yuan
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p. 407 - 410
(2019/01/14)
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- Photocatalytic hydrogenation of nitroarenes: supporting effect of CoOx on TiO2 nanoparticles
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Cobalt oxide visible light-active photo-catalysts supported on TiO2 nanoparticles with varying amount of cobalt oxide [3% CoOx/TiO2 (A), 4% CoOx/TiO2 (B), 5% CoOx/TiO2 (C)] were synthesized by solid-state method followed by calcination. The as-synthesized catalysts were characterized by various techniques such as powder XRD, TEM, EDX, UV-Vis-DRS and XPS analysis. The photocatalytic activity of the as-synthesized materials was studied for the reduction of nitroarenes to the corresponding amines using hydrazine monohydrate as the reductant. Cobalt(ii) oxide is responsible for the reduction of nitroarenes and then, cobalt(iii) is reduced back to the original compound by hydrazine hydrate, thus ascertaining the catalytic nature of this hydrogenation process. XPS suggests the presence of Co(ii) in CoOx/TiO2.
- Amanchi, Srinivasa Rao,Ashok Kumar,Lakshminarayana, Bhairi,Satyanarayana,Subrahmanyam
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p. 748 - 754
(2019/01/10)
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- Reduction of Nitroarenes to Anilines with a Benzothiazoline: Application to Enantioselective Synthesis of 2-Arylquinoline Derivatives
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The metal-free reduction of nitroarenes to aniline derivatives was accomplished in a short time by using a benzothiazoline as the hydrogen donor in combination with a Bronsted acid. An enantioselective synthesis of 2-arylquinolines was achieved by using 1-aryl-3-(2-nitrophenyl)propan-1-ones as starting materials and a combination of a benzothiazoline and a chiral phosphoric acid.
- Miyagawa, Masamichi,Yamamoto, Ryota,Kobayashi, Nanako,Akiyama, Takahiko
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supporting information
p. 499 - 502
(2019/02/26)
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- Bi-functional catalyst of porous N-doped carbon with bimetallic FeCu for solvent-free resultant imines and hydrogenation of nitroarenes
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The efficient and stable catalyst applied to the transformation of amines into the corresponding imines and hydrogenation of nitroarenes under mild reaction conditions is reported. The catalytic performance of porous N-doped carbon with FeCu (FeCu@NPC) catalyst are tested by aromatic alcohol-based N-alkylated of amines with solvent-free and hydrogenation of nitroarenes via N2H4·H2O. The results proved that the yield of these two reactions are all over 99.9% under optimum condition. Moreover, the synergistic effect of the catalyst for N-alkylated reaction was investigated through the kinetic study. The catalyst can be easily separated from reaction system by an external magnetism, and can be recycled and reutilized for at least 4 runs with conversions are all over 75%. The study of the catalyst indicated that it was suitable for the reactions in industry. Hence, the catalysis process by the inexpensive metals-based catalyst is green and sustainable.
- Wang, Kaizhi,Gao, Wenbing,Jiang, Pengbo,Lan, Kai,Yang, Ming,Huang, Xiaokang,Ma, Lei,Niu, Fang,Li, Rong
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- Fe/Fe2O3@N-dopped Porous Carbon: A High-Performance Catalyst for Selective Hydrogenation of Nitro Compounds
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Herein, we designed and prepared a novel Fe/Fe2O3-based catalyst, in which a remarkable synergistic effect has been revealed between Fe and Fe2O3 encapsulated in N-doping porous carbon. The Fe-based catalysts were fabricated via pyrolysis a mixture of MIL-101(Fe) and melamine. The catalyst exhibits exceptionally high catalytic activity (TOFs up to 8898 h?1 which is about 100 times higher than the similar kinds of catalysts) and chemoselectivity for nitroarene reduction under mild conditions.
- Yun, Ruirui,Hong, Lirui,Ma, Wanjiao,Jia, Weiguo,Liu, Shoujie,Zheng, Baishu
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p. 724 - 728
(2019/01/04)
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- High Selectivity of Hydrogenation Reaction over Co0.15@C/PC Catalyst at Room Temperature
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In the field of catalysis, material scientists pay much attention to tuning the activity and chemoselectivity of metal nanoparticles. Herein, we design and successfully synthesize a series of Co NPs which show high performance on hydrogenation of nitroarenes with both activity and chemoselectivity. Co0.15@C/PC preferentially activates the -C=O bond over -NO2 in water with ammonia borane (AB); however, when the hydrogen source is changes to hydrazine hydrate (HH), the results are the opposite. The Co-based catalyst exhibits exceptionally high catalytic activity (with a TOF value of 10512 h-1, which is approximately 100 times than the akin catalysts) and chemo-selectivity for the hydrogenation of nitro compounds under mild conditions. Additionally, the catalyst can be separated easily by a magnet and shows prominent stabilit, which means that it can be reused for at least 10 cycles.
- Yun, Ruirui,Ma, Wanjiao,Wang, Suna,Jia, Weiguo,Zheng, Baishu
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- Co-MOF-Derived Hierarchical Mesoporous Yolk-shell-structured Nanoreactor for the Catalytic Reduction of Nitroarenes with Hydrazine Hydrate
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Porous nanoreactors demonstrate immense potential for applications in heterogeneous catalysis due to their excellent mass-transfer performance and stability. The design of a simple, universal strategy for fabricating nanoreactor catalysts is of significance for organic transformation. In this study, a nanoreactor with a hierarchical mesoporous yolk-shell structure was successfully prepared by the high-temperature carbonization of a ZIF-67@polymer composite. The core of the resultant Co@ZDC@mC material comprised Co NPs anchored in the ZIF-67-derived carbon framework, while the shell comprised resin-polymer-derived mesoporous carbon. The as-obtained Co@ZDC@mC-700 catalyst enriched reactants, efficiently catalyzed the reaction in the core, and permitted the desorption of the product from the nanoreactor. In the catalytic reduction of nitrobenzene with N2H4?H2O, Co@ZDC@mC-700 exhibited superior catalytic efficiency (TOF=1136.3 h?1). In addition, Co@ZDC@mC-700 exhibited excellent performance for the catalytic reduction of various functionalized nitroarenes, as well as good reusability and recyclability. Hence, a simple, useful approach for fabricating a metal-organic-framework-derived non-noble metal-based yolk-shell nanoreactor for effective catalytic transformation is proposed.
- Yuan, Man,Zhang, Hongbo,Yang, Chen,Wang, Fanhao,Dong, Zhengping
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p. 3327 - 3338
(2019/07/04)
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- Selective Hydrogenation by Carbocatalyst: The Role of Radicals
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The selective hydrogenation of the nitro moiety is a difficult task in the presence of other reducible functional groups such as alkenes or alkynes. We show that the carbon-based (metal-free) catalyst can be used to selectively reduce substituted nitro groups using H2 as a reducing agent, providing a great potential to replace noble-metal catalysts and contributing to simple and greener strategies for organic synthesis.
- Ahmad, Muhammad Sohail,He, Huixin,Nishina, Yuta
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supporting information
p. 8164 - 8168
(2019/10/16)
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- Eco-friendly hydrogenation of aryl azides to primary amines on graphene oxide-decorated bimetallic Rh-Pt nanoparticles (RhPt@GO NPs)
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Graphene oxide-supported rhodium/platinum (Rh-Pt) nanoparticles (Rh-Pt@GO NPs) are a promising catalyst for the reduction of aryl azides to primary amines. Rh-Pt@GO NPs have been produced by the microwave-assisted sonochemical method. This catalyst showed superior catalytic activity to afford quantitative yields of primary amines under an extremely mild condition in the presence of sodium borohydride. The synthesized novel catalyst was easily recovered by centrifugation and reused without loss of its catalytic activity. The spectroscopic analyses of the RhPt@GO NPs indicated the formation of highly crystalline, monodisperse, and colloidally stable RhPt@GO NPs.
- Kilbas, Benan,Kara, Belguzar Yasemin
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- Unusual Chemistry in an Uncatalyzed Bromate-Aniline Oscillator: Ring-Contraction Oxidation of Aniline with Pulsative CO2 Production
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The bromate-aniline oscillatory reaction was discovered 4 decades ago, but neither the detailed mechanism nor the key products or intermediates of the reaction were described. We report herein a detailed study of this reaction, which yielded new insights. We found that oscillatory oxidation of aniline by acidic bromate proceeds, to a significant extent, via a novel reaction pathway with the periodic release of carbon dioxide. Several products were isolated, and their structures, not described so far, were justified on the basis of MS and NMR. One of the main products of the reaction associated with the CO2 release route can be assigned to 2,2-dibromo-5-(phenylimino)cyclopent-3-en-1-one. A number of known compounds produced in the studied reaction, including unexpected brominated 1-phenylpyrroles and 1-phenylmaleimides, were identified by comparison with standards. A mechanism is suggested to explain the appearance of the detected compounds, based on coupling of the anilino radical with the produced 1,4-benzoquinone. We assume that the radical adduct reacts with bromine to form a cyclopropanone intermediate that undergoes a Favorskii-type rearrangement. Further oxidation and bromination steps including decarboxylation lead to the found brominated phenyliminocyclopentenones. The detected derivatives of 1-phenylpyrrole could be produced by a one-electron oxidation of a proposed intermediate 2-phenylamino-5-bromocyclopenta-1,3-dien-1-ol followed by β-scission with the abstraction of carbon monoxide. Such a mechanism is known from the combustion chemistry of cyclopentadiene. The proposed mechanism of this reaction provides a framework for understanding the observed oscillatory kinetics.
- Valent, Ivan,Pribus, Marek,Novák, Filip,Plánková, Sylvia,Bla?ko, Jaroslav,Kubinec, Róbert,Almássy, Ambroz,Filo, Juraj,Sigmundová, Ivica,Sebechlebská, Táňa,Lawson, Thuy Bich,Noszticzius, Zoltán
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p. 9669 - 9681
(2019/11/14)
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- Ru-Catalyzed Deoxygenative Transfer Hydrogenation of Amides to Amines with Formic Acid/Triethylamine
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A ruthenium(II)-catalyzed deoxygenative transfer hydrogenation of amides to amines using HCO2H/NEt3 as the reducing agent is reported for the first time. The catalyst system consisting of [Ru(2-methylallyl)2(COD)], 1,1,1-tris(diphenylphosphinomethyl) ethane (triphos) and Bis(trifluoromethane sulfonimide) (HNTf2) performed well for deoxygenative reduction of various secondary and tertiary amides into the corresponding amines in high yields with excellent selectivities, and exhibits high tolerance toward functional groups including those that are reduction-sensitive. The choice of hydrogen source and acid co-catalyst is critical for catalysis. Mechanistic studies suggest that the reductive amination of the in situ generated alcohol and amine via borrowing hydrogen is the dominant pathway. (Figure presented.).
- Pan, Yixiao,Luo, Zhenli,Xu, Xin,Zhao, Haoqiang,Han, Jiahong,Xu, Lijin,Fan, Qinghua,Xiao, Jianliang
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supporting information
p. 3800 - 3806
(2019/07/12)
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- From alkylarenes to anilines via site-directed carbon–carbon amination
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Anilines are fundamental motifs in various chemical contexts, and are widely used in the industrial production of fine chemicals, polymers, agrochemicals and pharmaceuticals. A recent development for the synthesis of anilines uses the primary amination of C–H bonds in electron-rich arenes. However, there are limitations to this strategy: the amination of electron-deficient arenes remains a challenging task and the amination of electron-rich arenes has a limited control over regioselectivity—the formation of meta-aminated products is especially difficult. Here we report a site-directed C–C bond primary amination of simple and readily available alkylarenes or benzyl alcohols for the direct and efficient preparation of anilines. This chemistry involves a novel C–C bond transformation and offers a versatile protocol for the synthesis of substituted anilines. The use of O2 as an environmentally benign oxidant is demonstrated, and studies on model compounds suggest that this method may also be used for the depolymerization of lignin.
- Liu, Jianzhong,Qiu, Xu,Huang, Xiaoqiang,Luo, Xiao,Zhang, Cheng,Wei, Jialiang,Pan, Jun,Liang, Yujie,Zhu, Yuchao,Qin, Qixue,Song, Song,Jiao, Ning
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- Aromatic amine compound synthesis method
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The invention discloses an aromatic amine compound synthesis method which is characterized in that the method is implemented according to any of two methods. The first method includes the steps: mixing an alkyl aromatic compound with a general formula (I) and a nitrogen-containing compound with a general formula (II); performing reaction on mixture under an oxidizing agent and an organic solvent to obtain an aromatic amine compound with a general formula (III). The second method includes the steps: mixing an aromatic alcohol derivative with a general formula (I') and the nitrogen-containing compound with the general formula (II); performing reaction on mixture under an acid additive and an organic solvent to prepare the aromatic amine compound with the general formula (III). According to the method, a lot of alkyl aromatic compounds or aromatic alcohol derivatives firstly serve as raw materials, and the raw materials are reacted to generate the aromatic amine compound without the action of metal catalysis. Compared with a traditional synthesis method, the synthesis method has the advantages that the method is high in yield and simple in condition, waste discharging amount is less,metal participation is omitted, a reaction device is simple, industrial production is easily achieved and the like. The method has a wide application prospect.
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Paragraph 0145-0147
(2019/01/23)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0354-0356; 0359
(2019/01/07)
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- High catalytic activity of a new Ag phosphorus ylide complex supported on montmorillonite: synthesis, characterization, and application for room temperature nitro reduction
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In this work, the phosphorus ylide, [PPh3CHC(O)CH2Cl], was reacted with AgNO3 to give the [Ag{C(H)PPh3C(O)CH2Cl}2]+NO3? as the product. Then, it was supported on the modified montmorillonite nanoclay to prepare a new catalyst for the reduction reaction. The structure and morphology of the nanoclay catalyst were characterized by FT-IR, X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray analysis and transmission electron microscopy techniques; also, the content of silver was obtained by inductively coupled plasma analyzer. This composition was exploited to study its catalytic activity in the reduction in aromatic nitro compounds; it displayed the high catalytic activity. Factors such as catalyst amount, solvent, temperature and reaction time were all systematically investigated to elucidate their effects on the yield of catalytic reduction in nitroarenes. This catalytic system exhibited high activity toward aromatic nitro compounds under mild conditions. The catalyst was reused five times without any significant loss in its catalytic activity.
- Karami, Kazem,Rahimi, Mahzad,Dinari, Mohammad
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p. 281 - 291
(2018/03/29)
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- Magnetically Recyclable Metal–Organic Framework@Fe3O4 Composite-Catalyzed Facile Reduction of Nitroarene Compounds in Aqueous Medium
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A kind of Metal–organic framework (MOF) composite namely Cu-BTC@Fe3O4 (BTC?=?1,3,5-benzenetricarboxylate) was prepared and showed good catalytic activity toward the reduction of nitroarenes. This reaction proceeded smoothly under mild reaction conditions in aqueous medium using sodium borohydride as the reduction agent, affording the corresponding anilines in good to excellent yields. In addition, the catalyst could be easily recovered with an external permanent magnet and be reused for successive six runs with slight decrease in its activity.
- Yang, Sen,Zhang, Zhi-Hui,Chen, Qun,He, Ming-Yang,Wang, Liang
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- The Direct Synthesis of Imines, Benzimidazoles and Quinoxalines from Nitroarenes and Carbonyl Compounds by Selective Nitroarene Hydrogenation Employing a Reusable Iron Catalyst
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The “replacement” of noble metals by earth abundant metals is a desirable aim in catalysis and a possible way of conserving rare elements. The “replacement” is especially attractive if novel selectivity patterns are observed permitting the development of novel coupling reactions. Herein, we report on a novel, robust and reusable iron catalyst, which permits the selective hydrogenation of nitroarenes in the presence of hydrogenation-sensitive functional groups. Based on the selectivity pattern observed, the direct iron-catalyzed synthesis of imines and benzimidazoles from nitroarenes and aldehydes becomes feasible. In addition, we introduce the direct synthesis of quinoxalines from nitroarenes and diketones applying our catalyst.
- B?umler, Christoph,Kempe, Rhett
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supporting information
p. 8989 - 8993
(2018/05/30)
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- Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates
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The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N-oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation as well as for the gram-scale synthesis of several substrates of industrial importance.
- Gevorgyan, Ashot,Mkrtchyan, Satenik,Grigoryan, Tatevik,Iaroshenko, Viktor O.
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p. 375 - 382
(2018/06/04)
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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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- Pd-doped Ni nanoparticle-modified N-doped carbon nanocatalyst with high Pd atom utilization for the transfer hydrogenation of nitroarenes
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Palladium (Pd)-based catalysts with maximum utilization of the Pd atoms are attractive for hydrogenation reactions and conserving Pd resources. Herein, the highly dispersed Ni nanoparticle (NP)-modified mesoporous N-doped carbon (Ni/mCN) was successfully prepared by pyrolyzing a mixture of polyacrylonitrile, melamine and Ni(NO3)2·6H2O. Then, the resulting Ni/mCN material with highly dispersed metallic Ni NPs was treated with Pd(AcO)2, and Pd2+ was spontaneously reduced to metallic Pd by the Ni NPs, affording the PdNi NP-based catalyst (PdNi/mCN). The spontaneous reduction process deposits most of the Pd atoms on the surface of the Ni NPs, thus allowing for the maximum utilization of the noble metal Pd. The prepared mesoporous N-doped carbon support can not only provide more surface area to adsorb reaction substrates, but also enhances the accessibility of the active sites of PdNi NPs. The prepared PdNi/mCN nanocatalyst shows a very high catalytic activity for the transfer hydrogenation of nitroarenes using formic acid as the reductant under ambient conditions in aqueous solution, as compared to other Pd-based catalysts, probably because of the highly dispersed PdNi NPs and the maximum utilization of the Pd atoms, as well as the superior structure of mCN. Moreover, the PdNi/mCN nanocatalyst exhibits excellent recyclability and reusability, and the catalytic activity does not obviously decrease after ten reaction cycles. Therefore, we believe that this study should open a new frontier in the preparation of porous N-doped carbon-supported catalysts with maximum utilization of the noble metals for green and sustainable catalysis.
- Cui, Xueliang,Long, Yu,Zhou, Xia,Yu, Guiqin,Yang, Jin,Yuan, Man,Ma, Jiantai,Dong, Zhengping
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p. 1121 - 1130
(2018/03/13)
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- Enhanced catalytic performance of cobalt nanoparticles coated with a N,P-codoped carbon shell derived from biomass for transfer hydrogenation of functionalized nitroarenes
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The development of abundantly available base metal catalysts for organic transformations remains an important goal of chemical research. Herein, we report the first facile fabrication of active, inexpensive, and reusable cobalt nanoparticles (NPs) coated with a N,P-codoped carbon shell derived from naturally renewable biomass and earth-abundant, low-cost cobalt salt and PPh3. The entire process is operationally simple, straightforward, cost-effective and environmentally benign and can be used in mass production for practical application. The resultant catalysts allow for highly efficient and selective transfer hydrogenation of functionalized nitroarenes to the corresponding anilines using formic acid or ammonium formate as the hydrogen donor. Uniformly incorporated N and P into the carbon lattices exhibited synergistic effects with the encapsulated Co NPs to engineer the structure and composition of the catalyst, thereby substantially boosting the catalytic efficiency. The most active catalyst Co@NPC-800 exhibited outstanding activity and exclusive selectivity for the reduction of functionalized nitroarenes to anilines, especially those decorated with readily reducible functional groups. The catalyst demonstrated high stability and can be easily separated by using an external magnet for successive reuses without significant loss in both activity and selectivity.
- Duan, Yanan,Song, Tao,Dong, Xiaosu,Yang, Yong
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supporting information
p. 2821 - 2828
(2018/06/29)
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- Surfactant Assembly within Pickering Emulsion Droplets for Fabrication of Interior-Structured Mesoporous Carbon Microspheres
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Large-sized carbon spheres with controllable interior architecture are highly desired, but there is no method to synthesize these materials. Here, we develop a novel method to synthesize interior-structured mesoporous carbon microspheres (MCMs), based on the surfactant assembly within water droplet-confined spaces. Our approach is shown to access a library of unprecedented MCMs such as hollow MCMs, multi-chambered MCMs, bijel-structured MCMs, multi-cored MCMs, “solid” MCMs, and honeycombed MCMs. These novel structures, unattainable for the conventional bulk synthesis even at the same conditions, suggest an intriguing effect arising from the droplet-confined spaces. This synthesis method and the hitherto unfound impact of the droplet-confined spaces on the microstructural evolution open up new horizons in exploring novel materials for innovative applications.
- Liu, Dawei,Xue, Nan,Wei, Lijuan,Zhang, Ye,Qin, Zhangfeng,Li, Xuekuan,Binks, Bernard P.,Yang, Hengquan
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supporting information
p. 10899 - 10904
(2018/08/01)
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- Selective Photocatalytic Synthesis of Haloanilines from Halonitrobenzenes over Multifunctional AuPt/Monolayer Titanate Nanosheet
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Bimetallic alloy AuPt nanoclusters supported on monolayer H1.07Ti1.73O4·H2O nanosheets (AuPt/TN) jointly complete a rapid catalytic reaction toward hydrogenation of halonitrobenzene to haloaniline in methanol under ambient conditions using HCOONH4 as a hydrogen source. Especially, AuPt/TN with a Au/Pt molar ratio of 1:2 exhibits the high catalytic conversion efficiency for halonitrobenzene (>99%) with a high selectivity of haloaniline (>99%). In situ FTIR spectra suggest that the TN affords surface Br?nsted acid sites to chemisorb and activate the halonitrobenzene molecules via the surface hydrogen bond coordination. In situ ESR experiments indicate that HCOONH4 would be decomposed to H+ and a ?CO2- radical by photogenerated holes, serving as the hydrogen source and reducing species for the reduction of the -NO2 group, respectively. Experimental results reveal that atom Pt in alloy is responsible for the hydrogenation, while Au represses the dehalogenation of haloanilines. Finally, a possible synergetic mechanism is discussed. This work highlights that the multifunctional AuPt/TN catalyst with multiple active sites exerts the respective functions to cooperatively catalyze organic transformations toward desired target products.
- Song, Yujie,Wang, Huan,Wang, Zhitong,Guo, Binbin,Jing, Kaiqiang,Li, Yanjun,Wu, Ling
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p. 9656 - 9664
(2018/10/02)
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- Aminal-based Hypercrosslinked Polymer Modified with Small Palladium Nanoparticles for Efficiently Catalytic Reduction of Nitroarenes
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Fabrication of heterogeneous catalysts with excellent activity, selectivity and stability is significant for various catalytic applications. Here, we prepared a hypercrosslinked polymer (HCP) via a facile and cost-effective strategy using ferrocenecarboxaldehyde and melamine as building blocks. Then, the HCP was modified with highly dispersed ultrafine Pd nanoparticles (Pd/HCP). The obtained Pd/HCP shows excellent catalytic activity in the catalytic reduction of nitroarenes under mild reaction conditions. It′s worth mentioning that the N atoms in the HCP can efficiently coordinate Pd ions to form small Pd nanoparticles (NPs) and subsequently prevent the aggregation and leaching of Pd NPs during the reaction, so the Pd/HCP catalyst is highly stable and can be reused at least eight cycles without loss of catalytic activity. Therefore, this work may provide possibilities for using HCPs as ideal supporting materials for fabricating highly stable and efficient heterogeneous catalysts.
- Xu, Dan,Wang, Fushan,Yu, Guiqin,Zhao, Hong,Yang, Jing,Yuan, Man,Zhang, Xiaoyun,Dong, Zhengping
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p. 4569 - 4577
(2018/09/11)
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- A robust core-shell nanostructured nickel-iron alloy@nitrogen-containing carbon catalyst for the highly efficient hydrogenation of nitroarenes
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Currently, the catalytic selective hydrogenation of nitroarenes to produce aromatic amines is one of the most important key reactions in many fine chemical processes. In particular, non-noble-metal-catalyzed hydrogenation of nitroarenes represents more sustainable chemical processes. Here, we report a new robust and recyclable core-shell nanostructured nickel-iron alloy@nitrogen-containing carbon (NiFe@NC) catalyst and the beneficial effect of alloying Ni with Fe for the above reaction. The key to this synthetic strategy was thermally transforming the Ni-Fe layered double hydroxide (NiFe-LDH)/melamine mixture to form a fixed NiFe@NC nanostructure. A series of characterization results revealed the formation of NiFe alloy nanoparticles (NPs) coated with the NC overlayer. The as-fabricated NiFe@NC catalyst with a Ni/Fe atomic ratio of 3.0 exhibited superior activity for the reduction of the nitro group in o-chloronitrobenzene, with a 99.5% yield of o-chloroaniline under mild reaction conditions. The initial reaction rate over the catalyst was nearly three times that over the monometallic Ni@NC counterpart, and even one-order magnitude higher than that over pristine NiFe-LDH-derived NiFe alloy NPs. The extraordinary activity of NiFe@NC was reasonably attributed to the unique core-shell nanostructure, where both the NiFe alloy core and the NC overlayer shell could construct a significant promotional effect, being beneficial for the selective cleavage of the N-O bond. Recycling experiments indicated that the catalyst could be easily separated and recovered under an external magnetic field and experienced excellent recyclability during seventeen cycles without an obvious loss of catalytic activity. Furthermore, the present catalyst was also highly active for the chemoselective hydrogenation of other substituted nitroarenes bearing different functional groups to the corresponding anilines.
- Zhang, Yaowen,Liu, Chunling,Fan, Guoli,Yang, Lan,Li, Feng
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p. 13668 - 13679
(2018/10/15)
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