- Subnanometer Bimetallic Platinum–Zinc Clusters in Zeolites for Propane Dehydrogenation
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Propane dehydrogenation (PDH) has great potential to meet the increasing global demand for propylene, but the widely used Pt-based catalysts usually suffer from short-term stability and unsatisfactory propylene selectivity. Herein, we develop a ligand-protected direct hydrogen reduction method for encapsulating subnanometer bimetallic Pt–Zn clusters inside silicalite-1 (S-1) zeolite. The introduction of Zn species significantly improved the stability of the Pt clusters and gave a superhigh propylene selectivity of 99.3 % with a weight hourly space velocity (WHSV) of 3.6–54 h?1 and specific activity of propylene formation of 65.5 mol (Formula presented.) gPt?1 h?1 (WHSV=108 h?1) at 550 °C. Moreover, no obvious deactivation was observed over PtZn4?S-1-H catalyst even after 13000 min on stream (WHSV=3.6 h?1), affording an extremely low deactivation constant of 0.001 h?1, which is 200 times lower than that of the PtZn4/Al2O3 counterpart under the same conditions. We also show that the introduction of Cs+ ions into the zeolite can improve the regeneration stability of catalysts, and the catalytic activity kept unchanged after four continuous cycles.
- Cheng, Jun,Fan, Qiyuan,Jia, Ran,Jiang, Zheng,Li, Lin,Mayoral, Alvaro,Miao, Shu,Sun, Qiming,Terasaki, Osamu,Wang, Ning,Wang, Ye,Xu, Jun,Yang, Dong-Chun,Yang, Ruoou,Yu, Jihong,Zeng, Lei,Zhang, Jichao,Zhang, Peng,Zhang, Qinghong,Zhang, Tianjun,Zhou, Wei
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Read Online
- Impregnating Subnanometer Metallic Nanocatalysts into Self-Pillared Zeolite Nanosheets
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Impregnation is the most commonly used approach to prepare supported metal catalysts in industry. However, this method suffers from the formation of large metal particles with uneven dispersion, poor thermal stability, and thus unsatisfied catalytic performance. Here, we demonstrate that the self-pillared MFI zeolite (silicalite-1 and ZSM-5) nanosheets with larger surface area and abundant Si-OH groups are ideal supports to immobilize ultrasmall monometallic (e.g., Rh and Ru) and various bimetallic clusters via simple incipient wetness impregnation method. The loaded subnanometric metal clusters are uniformly dispersed within sinusoidal five-membered rings of MFI and remain stable at high temperatures. The Rh/SP-S-1 is highly efficient in ammonia borane (AB) hydrolysis, showing a TOF value of 430 molH2 molRh-1 min-1 at 298 K, which is more than 6-fold improvement over that of nanosized zeolite-supported Rh catalyst and even comparable with that of zeolite-supported Rh single-atom catalyst. Because of the synergistic effect between bimetallic Rh-Ru clusters and zeolite acidity, the H2 generation rate from AB hydrolysis over Rh0.8Ru0.2/SP-ZSM-5-100 reaches up to 1006 molH2 molmetal-1 min-1 at 298 K, and also shows record activities in cascade hydrogenation of various nitroarenes by coupling with the hydrolysis of AB. This work demonstrates that zeolite nanosheets are excellent supports to anchor diverse ultrasmall metallic species via the simple impregnation method, and the obtained nanocatalysts can be applied in various industrially important catalytic reactions.
- Wang, Ning,Sun, Qiming,Zhang, Tianjun,Mayoral, Alvaro,Li, Lin,Zhou, Xue,Xu, Jun,Zhang, Peng,Yu, Jihong
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Read Online
- 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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- C-H Amination of Arenes with Hydroxylamine
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This Letter describes the development of a TiIII-mediated reaction for the C-H amination of arenes with hydroxylamine. This reaction is applied to a variety of electron-rich (hetero)arene substrates, including a series of natural products and pharmaceuticals. It offers the advantages of mild conditions (room temperature), fast reaction rates (30 min), compatibility with ambient moisture and air, scalability, and the use of inexpensive commercial reagents.
- See, Yi Yang,Sanford, Melanie S.
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supporting information
p. 2931 - 2934
(2020/04/09)
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- Method for continuous hydrogenation preparation of aromatic amine through nitro-compound
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The invention provides a method for continuous hydrogenation preparation of aromatic amine through a nitro-compound, and belongs to the field of heterogeneous catalysis. The method comprises the stepsthat the nitro-compound serves as a raw material, nano-porous palladium serves as a catalyst and hydrogen serves as a hydrogen source; a static bed liquid phase catalysis hydrogenation process is utilized for synthesizing the nitro-compound into the aromatic amine, and the activity of the catalyst is not lowered after 400-hour continuous running of the catalyst; continuous hydrogenation is carried out under the catalysis condition of the nano-porous palladium catalyst to obtain an aromatic amine product. The method is mild in reaction condition, high in reaction selectivity, compatible in substrate and good in stability, and industrial production is facilitated.
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Paragraph 0042-0043
(2019/06/27)
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- Zeolite-Encaged Single-Atom Rhodium Catalysts: Highly-Efficient Hydrogen Generation and Shape-Selective Tandem Hydrogenation of Nitroarenes
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Single-atom catalysts are emerging as a new frontier in heterogeneous catalysis because of their maximum atom utilization efficiency, but they usually suffer from inferior stability. Herein, we synthesized single-atom Rh catalysts embedded in MFI-type zeolites under hydrothermal conditions and subsequent ligand-protected direct H2 reduction. Cs-corrected scanning transmission electron microscopy and extended X-ray absorption analyses revealed that single Rh atoms were encapsulated within 5-membered rings and stabilized by zeolite framework oxygen atoms. The resultant catalysts exhibited excellent H2 generation rates from ammonia borane (AB) hydrolysis, up to 699 min?1 at 298 K, representing the top level among heterogeneous catalysts for AB hydrolysis. The catalysts also showed superior catalytic performance in shape-selective tandem hydrogenation of various nitroarenes by coupling with AB hydrolysis, giving >99 % yield of corresponding amine products.
- Sun, Qiming,Wang, Ning,Zhang, Tianjun,Bai, Risheng,Mayoral, Alvaro,Zhang, Peng,Zhang, Qinghong,Terasaki, Osamu,Yu, Jihong
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supporting information
p. 18570 - 18576
(2019/11/25)
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- Direct conversion of phenols into primary anilines with hydrazine catalyzed by palladium
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Primary anilines are essential building blocks to synthesize various pharmaceuticals, agrochemicals, pigments, electronic materials, and others. To date, the syntheses of primary anilines mostly rely on the reduction of nitroarenes or the transition-metal-catalyzed Ullmann, Buchwald-Hartwig and Chan-Lam cross-coupling reactions with ammonia, in which non-renewable petroleum-based chemicals are typically used as feedstocks via multiple step syntheses. A long-standing scientific challenge is to synthesize various primary anilines directly from renewable sources. Herein, we report a general method to directly convert a broad range of phenols into the corresponding primary anilines with the cheap and widely available hydrazine as both amine and hydride sources with simple Pd/C as the catalyst.
- Qiu, Zihang,Lv, Leiyang,Li, Jianbin,Li, Chen-Chen,Li, Chao-Jun
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p. 4775 - 4781
(2019/05/16)
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- Highly efficient reduction of nitro compounds: Recyclable Pd/C-catalyzed transfer hydrogenation with ammonium formate or hydrazine hydrate as hydrogen source
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Herein, we described a highly efficient heterogeneous Pd/C-catalyzed transfer hydrogenation of nitro compounds for the synthesis of primary amines, using ammonium formate and hydrazine hydrate as hydrogen source independently. The products were obtained with up to >99% yield. Furthermore, gram scale and recycling of catalyst had been tested with well results.
- Chen, Xia,Zhou, Xiao-Yu,Wu, Hong,Lei, Yi-Zhu,Li, Jin-Hui
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supporting information
p. 2475 - 2484
(2018/10/25)
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- Multi-phase catalytic hydrogenation reduction method of unsaturated compound
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The invention discloses a multi-phase catalytic hydrogenation reduction method of an unsaturated compound. The method comprises a step of carrying out multi-phase catalytic hydrogenation reaction to reduce the unsaturated compound; the multi-phase catalytic hydrogenation reaction takes water as a solvent and a hydrophobic and atmophile material as a catalyst. According to the multi-phase catalytichydrogenation reduction method, hydrophobic and atmophile properties of the catalyst are utilized, so that hydrogen gas can be rapidly adsorbed and spread on the surface of the catalyst, the surfacehydrogen concentration of the catalyst is improved, and the hydrogenation reaction speed is improved; a conventional pressurizing method is changed, so that requirements on equipment and dangerousnessare reduced. The atmophile catalyst Pd/GA can be used for hydrogenation of double bonds, nitryl and an aldehyde group under normal pressure, and is applicable to wide types. The method provided by the invention has a wide application potential in other fields needing gas to react.
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Paragraph 0050; 0051; 0052; 0053; 0054
(2019/04/26)
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- Development of a novel protocol for chemoselective deprotection of N/O-benzyloxycarbonyl (Cbz) at ambient temperature
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Abstract: A novel protocol for the deprotection of N-benzyloxycarbonyl and O-benzyloxycarbonyl groups by nickel boride generated in situ from NaBH4 and NiCl2·6H2O in methanol at room temperature has been developed to give the corresponding amines and phenols. This protocol is chemoselective as groups like chloro, bromo, amide, ester, pyridine, and tert-butyloxycarbonyl moiety are unaffected under these conditions. The deprotection has also been validated in gram scale reactions, to establish the wider appropriateness of this protocol. Graphical abstract: [Figure not available: see fulltext.].
- Saroha, Mohit,Aggarwal, Komal,Bartwal, Gaurav,Khurana, Jitender M.
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p. 2231 - 2235
(2018/10/02)
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- Palladium nanoparticles stabilized by aqueous vesicles self-assembled from a PEGylated surfactant ionic liquid for the chemoselective reduction of nitroarenes
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Vesicles self-assembled from an aqueous PEGylated surfactant ionic liquid solution can be applied for stabilizing palladium nanoparticles, which prove to be an efficient catalytic system for chemoselective hydrogen transfer of nitroarenes using hydrazine hydrate as a hydrogen source. The particle sizes of vesicles are decreased with the increase of ionic liquid's concentrations and relatively small particle sizes are beneficial to the reduction. Moreover, the aqueous catalytic system still stays in reactor by simple extraction, and is reused without further treatment.
- Xu, Zhu-bing,Lu, Guo-ping,Cai, Chun
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- Constructing magnetic Si-C-Fe hybrid microspheres for room temperature nitroarenes reduction
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In this work, we present, for the first time, the synthesis and characterization of magnetic Si-C-Fe hybrid microspheres and their catalytic performance in room temperature reduction of 4-nitrophenol as a representative sustainable process for converting environmental pollutants to fine chemicals. The ferrocene-modified polydivinylbenzene (Fc-PDVB) precursor was synthesized by Pt-catalyzed hydrosilylation between the residual vinyl groups on the PDVB surface and 1,1′-bis (dimethylsilyl)ferrocene, where further pyrolysis led to the formation of Fe nanocrystal-containing Si-C-Fe hybrid microspheres. The precursor and hybrid microspheres were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), BET surface area/porosity, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), magnetic properties and MAS solid-state NMR measurements. The ultimate microspherical catalyst exhibited nano- and meso-pores, a high specific surface area (i.e., 347.9 m2 g-1) and good ferromagnetic properties. Efficient catalytic activity (TOF: 0.163 s-1), 100% selectivity (to 4-aminophenol) and excellent reusability (with easy separation) have been delivered. The achieved microspheres outperform a number of nanomaterials such as supported noble metal particles, composites, monoliths and sheets. We have confirmed by DFT calculations that the activation of 4-nitrophenol via its weak non-covalent interaction with the sp2 carbon domain of Si-C-Fe hybrid microspheres contributed to the superior performance which can be extended to a range of nitrobenzenes.
- Zhang, Xiaofei,Chen, Lixin,Yun, Jin,Wang, Xiaodong,Kong, Jie
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p. 10986 - 10997
(2017/07/11)
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- Fe-Catalyzed Amination of (Hetero)Arenes with a Redox-Active Aminating Reagent under Mild Conditions
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A novel and efficient Fe-catalyzed direct C?H amination (NH2) of arenes is reported using a new redox-active aminating reagent. The reaction is simple, and can be performed under air, mild, and redox-neutral conditions. This protocol has a broad substrate scope and could be used in the late-stage modification of bioactive compounds. Mechanistic studies demonstrate that a radical pathway could be involved in this transformation.
- Liu, Jianzhong,Wu, Kai,Shen, Tao,Liang, Yujie,Zou, Miancheng,Zhu, Yuchao,Li, Xinwei,Li, Xinyao,Jiao, Ning
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supporting information
p. 563 - 567
(2017/01/18)
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- A highly efficient heterogeneous copper-catalysed cascade reaction of aryl iodides with acetamidine hydrochloride leading to primary arylamines
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A highly efficient heterogeneous copper-catalysed cascade reaction of aryl iodides with acetamidine hydrochloride was achieved in DMF in the presence of 10 mol% of an MCM-41-immobilised L-proline-copper(I) complex (MCM-41-L-proline-CuI) with Cs2CO3 as base, yielding a variety of primary arylamines in good to excellent yields. The new heterogeneous copper complex can be easily prepared from commercially readily available and inexpensive reagents, recovered by a simple filtration of the reaction solution and used at least seven more times without any decrease in activity.
- Huang, Xue,Xiao, Ruian,You, Chongren,Yan, Tao,Cai, Mingzhong
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p. 315 - 320
(2017/06/19)
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- Chemoselective transfer hydrogenation of nitroarenes by highly dispersed Ni-Co BMNPs
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Highly dispread Ni-Co bimetallic nanoparticles (Ni-Co BMNPs) are synthesized and applied as an efficient catalyst in the chemoselective transfer hydrogenation of nitroarenes (CTH) using hydrazine hydrate as the hydrogen donor. The BMNPs can efficiently catalyze the reduction reaction without any additives under mild conditions with high TOF. Significantly higher activity is achieved when compared with corresponding single-component catalysts, optimal composition of the Ni-Co BMNPs was screened which was proved to be crucial in both the selectivity and yields. Excellent performance of Ni-Co BMNPs can be ascribed to the improved dispersion of active sites on the BMNPs surface (compared with Ni NPs) and the electron transfer from cobalt to nickel.
- Zhang, Jia-Wei,Lu, Guo-Ping,Cai, Chun
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- Electrophilic amination of aromatics with sodium azide in BF3-H2O
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Boron trifluoride monohydrate is an excellent Br?nsted acid catalyst system for a wide range of reactions. It is a non-oxidizing acid catalyst prepared easily by bubbling BF3 into water. We have found boron trifluoride monohydrate/sodium azide combination to be an efficient reagent system for aromatic electrophilic amination. The present method avoids the use of expensive superacids such as trifluoromethanesulfonic acid and provides a facile access to aromatic amines directly from aromatics.
- Prakash, G.K. Surya,Gurung, Laxman,Marinez, Eric R.,Mathew, Thomas,Olah, George A.
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supporting information
p. 288 - 291
(2016/01/12)
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- Synthesis method of riboflavin medical intermediate 3,4-dimethylaniline
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The invention relates to a synthesis method of a riboflavin medical intermediate 3,4-dimethylaniline. The synthesis method of the riboflavin medical intermediate 3,4-dimethylaniline is characterized by comprising the following steps: adding 2.3mol of ortho-xylene, 0.16mol of aluminum powder, 2.6-2.9mol of methylamine and 0.27mol of stannous chloride into a reaction vessel, raising solution temperature to 160-170 DEG C, controlling reaction pressure to be 2.6-2.8MPa and reaction time to be 21-23 hours, lowering the solution temperature to 21-25 DEG C, discharging solution, separating an organic layer, adding 110ml of potassium hydrogen sulfite solution into the organic layer, carrying out atmospheric distillation, cooling distillate, then separating out crystals, carrying out suction filtration, adding the crystals into 800ml of oxalic acid solution, controlling stirring rate to be 130-170rpm for dissolving the crystals, extracting for 3-5 times with cyclohexane, regulating pH of a water layer to be 9-10 with potassium sulfite solution, carrying out atmospheric distillation, cooling distillate, separating out solids, dissolving the solids into propionitrile, dehydrating by adopting a dehydrating agent, carrying out reduced pressure distillation, collecting fraction at the temperature of 90-95 DEG C, and recrystallizing in ethyl acetate, so that 3,4-dimethylaniline crystals are obtained.
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Paragraph 0014; 0015
(2016/11/21)
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- Preparation and characterization of Ni/mZSM-5 zeolite with a hierarchical pore structure by using KIT-6 as silica template: An efficient bi-functional catalyst for the reduction of nitro aromatic compounds
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Ni/mZSM-5 and Ni/H-mZSM-5 were synthesized as hierarchical (micro/meso porous) ZSM-5 zeolites by an indirect template method for the first time. The resulting zeolite materials exhibited significantly enhanced diffusional properties in comparison to purely microporous zeolite materials. The structural and morphological characterization of the prepared catalysts was investigated using XRD, BET, atomic absorption spectroscopy, FT-IR, 27Al-MAS NMR, SEM, TEM, XPS and DRS-UV techniques. These hierarchical zeolites were used as acid-metal bi-functional heterogeneous catalysts for hydride transfer in the reduction of nitro aromatic compounds. In these reactions, NaBH4 was used as a reducing agent. Excellent yields at room temperature and very short reaction times in aqueous media conditions were obtained. Reusability experiments showed the excellent stability of Ni/mZSM-5 and Ni/H-mMZSM-5 and the catalysts could be reused 7 times without much loss of activity in reduction of nitro aromatic compounds. Surprisingly, the acid form of Ni/H-mZSM-5 showed much higher activity than that of Ni/mZSM-5. High yield, short reaction time, green solvent (water), room temperature, no by-product, the easy reusability of catalysts and the low amounts of catalyst required are some of the advantages of these catalysts.
- Mazaheri, Omid,Kalbasi, Roozbeh Javad
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p. 34398 - 34414
(2015/04/27)
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- Efficient and highly selective boron-doped carbon materials-catalyzed reduction of nitroarenes
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Exploring the potential catalytic applications of boron-doped carbon materials is a fascinating challenge. Here we describe that boron-doped onion-like carbon and carbon nanotubes as metal-free catalysts exhibit excellent catalytic activity and stability in nitroarene reduction under a stoichiometric amount of reductant.
- Lin, Yangming,Wu, Shuchang,Shi, Wen,Zhang, Bingsen,Wang, Jia,Kim, Yoong Ahm,Endo, Morinobu,Su, Dang Sheng
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p. 13086 - 13089
(2015/08/18)
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- Magnetically separable CuFe2O4 nanoparticles in PEG: A recyclable catalytic system for the amination of aryl iodides
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A recyclable catalytic system comprising magnetically separable CuFe 2O4 nanoparticles in a poly(ethylene glycol) medium has been established as an inexpensive, nontoxic, environmentally benign system for the amination of aryl iodides with aqueous ammonia. A wide variety of aryl iodides underwent amination to afford the corresponding aryl amines in moderate to good yields. The catalytic system was recycled five times with consistent activity. Georg Thieme Verlag Stuttgart . New York.
- Kumar, A. Suresh,Ramani,Sreedhar
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supporting information
p. 938 - 942
(2013/06/27)
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- CuI-nanoparticles-catalyzed selective synthesis of phenols, anilines, and thiophenols from aryl halides in aqueous solution
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CuI-nanoparticles-catalyzed selective synthesis of phenols, anilines, and thiophenols from aryl halides was developed in the absence of both ligands and organic solvents. Anilines were formed selectively with ammonia competing with hydroxylation and thiophenols were generated selectively with sulfur powder after subsequent reduction competing with hydroxylation and amination.
- Xu, Hua-Jian,Liang, Yu-Feng,Cai, Zhen-Ya,Qi, Hong-Xia,Yang, Chun-Yan,Feng, Yi-Si
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supporting information; experimental part
p. 2296 - 2300
(2011/06/17)
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- Ecofriendly solvent free microwave enhanced alkyl migration in N-alkyl anilines in dry media conditions
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A rapid, cleaner, cost effective and ecofriendly synthesis of exclusive para alkyl anilines in solvent free conditions using solid supports under microwave irradiation is achieved.
- Selvakumar,Easwaramurthy,Raju
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p. 713 - 715
(2008/09/18)
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- Liquid-liquid-liquid phase transfer catalysis: A novel and green concept for selective reduction of substituted nitroaromatics
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The selective reduction of nitroaromatics to the corresponding amines is an important transformation since many aromatic amines exhibit biological activities and find a multitude of industrial applications, being intermediates for the synthesis of dyes, pharmaceuticals and agrochemicals. A variety of nitroaromatics dissolved in organic solvents was reduced by using aqueous sodium sulfide, and tetrabutylammonium bromide (TBAB) as the phase transfer catalyst by choosing appropriate concentrations which resulted in three immiscible liquid phases. Compared to L-L PTC, the L-L-L PTC offers much higher rates of reaction, better selectivities and repeated use of catalyst. The selectivities for the desired products were 100%.
- Yadav, Ganapati D.,Lande, Sharad V.
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p. 1235 - 1241
(2007/10/03)
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- Electrophilic Amination of Methylbenzenes with the System NaN 3-AlCl3-HCl. Effects of the Solvent, Crown Ether, and Substrate Structure
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Using mesitylene and o-xylene as examples, it was shown that the solvent nature strongly affects the conversion of methylbenzenes in electrophilic amination with the system NaN3-AlCl3-HCl. Two-parameter correlations were found between the substrate conversion, on the one hand, and dielectric constant and number of heavy atoms in the solvent, on the other. A considerable solvent effect on the regioselectivity of amination of o-xylene was observed. The presence of 18-crown-6 weakly affects the ratio of isomeric amines, but the conversion of o-xylene sharply decreases. Solid aromatic substrates, such as durene and pentamethylbenzene can also be involved in electrophilic amination with the system NaN3-AlCl3-HCl. On the basis of the experimental data and the results of quantum-chemical calculations, participation of a nitrenium intermediate in this reaction was postulated.
- Borodkin,Elanov,Popov,Pokrovskii,Shubin
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p. 672 - 679
(2007/10/03)
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- Synthetic reactions using metal powders under microwave irradiation
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Liquid-phase synthetic reactions that require the use of metal powders are widely regarded as being unsuited to heating with microwave radiation, as they tend to exhibit destructive arcing. In a previous paper, we examined the factors that lead to arcing in these systems and, hence, how it may be controlled. This paper describes the application of those findings in a range of microwave-induced syntheses of organometallic and organic compounds, where metal powders are necessary. Although reaction yields were similar to those observed when conventional heating is used, the rapid nature of microwave heating leads to a slight reduction in reaction times.
- Whittaker,Mingos
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p. 3967 - 3970
(2007/10/03)
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- Xenon difluoride-trimethylsilyl isocyanate-triflic acid as a new system for the amination of aromatic compounds
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In the title system, OCNXeOSO2CF3 is formed, which readily oxidises iodobenzene to [PhI+-NCO -OTf]. The direct amination of aromatic substrates is possible with the use of XeF2-Me3SiNCO-CF3SO3H.
- Pirkuliev,Brel,Akhmedov,Zefirov,Stang
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p. 172 - 173
(2007/10/03)
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- Photochromic spiroxazines, compositions and articles containing them
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The invention concerns photochromic compounds having a formula (I), where R1 is a polycyclo group formed by at least one alicyclic group linked to, bridged or condensed, with at least one other aliphatic or aromatic ring. STR1
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- Direct Aromatic Amination by Azides: Reactions of Hydrazoic Acid and Butyl Azides with Aromatic Compounds in the Presence of Both Trifluoromethanesulfonic Acid and Trifluoroacetic Acid
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Reactions of hydrazoic acid with aromatic compounds in the presence of both trifluoromethanesulfonic acid (TFSA) and trifluoroacetic acid (TFA) efficiently gave primary arylamines without diamine contaminants.The reactions provide mainly the ortho- and para-monoamines wven for readily oxidised aromatic compounds such as cumene, mesitylene, durene, isodurene and anisole.The mechanistic investigation demonstrates that the reactions proceed via a concerted process involving both arene attack on a conjugate acid of the azide and elimination of N2 from the conjugate acid.The reaction of butyl azide with benzene and mesitylene in the presence of both TFSA and TFA produced N-butylarylamines in low yields together with high yields of butanal via a butylnitrenium ion intermediate; a similar reaction with tert-butyl azide gave no tert-butylarylamines.
- Takeuchi, Hiroshi,Adachi, Taki,Nishiguchi, Hideaki,Itou, Katsutaka,Koyama, Kikuhiko
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p. 867 - 870
(2007/10/02)
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- REDUCTION WITH METAL BOROHYDRIDE-TRANSITION METAL SALT SYSTEM. I. REDUCTION OF AROMATIC NITRO COMPOUNDS WITH POTASSIUM BOROHYDRIDE-COPPER(I) CHLORIDE
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Upon treatment with potassium borohydride-copper(I) chloride, aromatic nitro compounds afforded cleanly primary amines in high yields.Similarly, nitroso-, azoxy-, and azobenzene were reduced by the same reagent system to give aniline.
- He, Yun,Zhao, He,Pan, Xinfu,Wang, Shaofei
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p. 3047 - 3050
(2007/10/02)
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- Intramolecular Selectivity of the Alkylation of Substituted Anilines by Gaseous Cations
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The intramolecular selectivity of the electrophilic reactions of Et(1+), i-Pr(1+), and Me2F(1+) cations with substituted anilines, including m-toluidine, m-anisidine, and m- and p-fluoroaniline, has been investigated in the dilute gas state at pressures ranging from 100 to 720 torr by a radiolytic technique, complemented by chemical ionization mass spectrometry.The results indicate an appreciable kinetic bias for the nitrogen atom, leading to predominant N-methylation by Me2F(1+).The reactivity of the carbenium ions is complicated by the simultaneous occurrence of proton transfer, in particular to the NH2 group, which increases the relative extent of ring alkylation.The positional selectivity is characterized, aside from the usual orienting effects of the substituents, by the enchanced reactivity of the ring positions ortho to an n-type substituent, irrespective of its activating or deactivating properties.The effect is traced to the preliminary formation of an electrostatic adduct between the aniline and the gaseous electrophile.
- Attina, Marina,Cacace, Fulvio,de Petris, Giulia
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p. 1556 - 1561
(2007/10/02)
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- Amination/demethylation process
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This invention relates to the intramolecular oxidation and reduction of aromatic hydrocarbons containing at least one methyl group and a nitro group ortho to the methyl group. Further, it relates to preparing methyl o-amino arylcarboxylates and aromatic amines. The process comprises reacting aromatic hydrocarbons having at least one methyl group and a nitro group ortho to the methyl group in a solvent at a temperature of about 450° to 750° C. When the solvent is methanol, methyl o-amino arylcarboxylates useful in anesthetics, printing inks for polyethylene, and useful in the manufacture of azo dyes are produced. Novel substituted methyl anthranilates have been produced which have the foregoing uses. When no solvent is used or the solvent is benzene, cyclohexane, toluene, hexafluorobenzene or any other non-reactive solvent, the compounds are demethylated and aromatic amines are produced. These aromatic amines are useful as pesticides, anti-oxidants and as pickling inhibitors for aluminum and zinc and as curing agents for epoxy resins.
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- Manufacture of aromatic amino compounds
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A process for producing an aromatic amine comprises heating an aromatic sulfonate and a metal amide in liquid ammonia in a closed reactor at a temperature of at least 40° C to produce a metal arylamide and reacting the resultant metal arylamide with water or lower aliphatic alcohol to produce an aromatic amine.
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