554-00-7Relevant articles and documents
Efficient and recyclable bimetallic Co–Cu catalysts for selective hydrogenation of halogenated nitroarenes
Lu, Xionggang,Ren, Jiaan,Sheng, Yao,Wang, Xueguang,Wu, Baoqin,Zou, Xiujing
, (2021/12/20)
Silica supported N-doped carbon layers encapsulating Co–Cu nanoparticles (Co1Cux@CN/SiO2) were prepared by a one-step impregnation of Co(NO3)2·6H2O, Cu(NO3)2·3H2O, urea and glucose, following in situ carbothermal reduction. Effects of Cu contents on the catalytic performance of the Co1Cux@CN/SiO2 catalysts were investigated for selective hydrogenation of p-chloronitrobenzene to p-chloroaniline. The Co1Cu0.30@CN/SiO2 with Cu/Co molar ratio of 0.30:1 presented much higher activity and stability than the monometallic Co@CN/SiO2 catalyst. The addition of Cu into Co1Cux@CN/SiO2 catalysts had favorable effects on the formation of highly active Co–N sites and N-doped carbon layer. The role of the N-doped carbon layer was to protect the Co from oxidation by air, and the Co1Cu0.30@CN/SiO2 could be reused for at least 12 cycles without decrease in catalytic efficiency. Mechanistic and in situ infrared studies revealed that the interaction effect between the Co and Cu atoms made the surface of Co highly electron rich, which decreased adsorption of halogen groups and resulting in the enhanced selectivity during chemoselective hydrogenation of halogenated nitroarenes for a wide scope of substrates.
A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
Bastos, Gustavo A.,de Mattos, Marcio C.S.
, (2021/09/29)
A simple, efficient and pot-economic approach in a single vessel has been developed for conversion of aromatic and aliphatic carboxamides into primary amines with one fewer carbom atom (Hofmann reaction) in 38–89 % yield by reacting with trichloro- or tribromoisocyanuric acid and sodium hydroxide in aqueous acetonitrile. Under the same reaction conditions, cyclic imides gave amino acids (69–83 %). The role of the trihaloisocyanuric acids is the in situ generation of N-haloamides, key-intermediates for the Hofmann reaction. The scalability of the methodology was demonstrated by a multigram-scale transformation of phthalimide into anthranilic acid in 77 % yield.
Method for preparing dichloroaniline through chlorination
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Paragraph 0027-0040, (2021/02/13)
The invention relates to a method for preparing dichloroaniline by chlorination. The method comprises the following steps: adding o-chloroaniline into a solvent, and carrying out chlorination reactionat 0-80 DEG C for 2-12 hours; neutralizing the reaction solution with alkali until the pH value is 9-10, and separating the organic phase from the water phase to obtain an organic phase; and carryingout rectification separation on the organic phase to respectively obtain pure products 2,4-dichloroaniline and 2,6-dichloroaniline. According to the invention, the main raw material o-chloroaniline is easy to obtain and low in price, so that the method has relatively high economical efficiency; the method has the advantages of no need of special reagents or solvents, one-step chlorination reaction, mild reaction conditions, simple operation, less wastewater, simple treatment and environmental friendliness, and only generates a small amount of salt-containing wastewater in the neutralization step; and the total yield is greater than 90%, and the purity can reach 99.5% or above, which is higher than the purity of 99% of the product in the prior art.
A Pd confined hierarchically conjugated covalent organic polymer for hydrogenation of nitroaromatics: Catalysis, kinetics, thermodynamics and mechanism
Awasthi, Satish Kumar,Yadav, Deepika
, p. 4295 - 4303 (2020/07/30)
Herein, we propose a fast and scalable synthesis of a triazine based hierarchically conjugated covalent organic polymer under solvent and additive free conditions through a single step process. The synthesized material CCTP (Cyanuric Chloride-Thiourea-Polymer) was thoroughly characterized by various physicochemical techniques. The CCTP exhibited regular sponginess and excellent chemical as well as thermal stability. The solvent and additive free approach for CCTP synthesis provides a sustainable alternative for classical solvothermal methods. The CCTP was immobilized with Pd (0) and subsequently a heterogeneous material Pd&at;CCTP was obtained, which was used as an efficient catalyst for the hydrogenation of nitroarenes. The rate constant and Ea were measured to be 2.08 × 10-2 s-1 and 15.67 kJ mol-1 respectively and thereafter other thermodynamic parameters like ΔH, ΔS and ΔG for the hydrogenation of p-nitrophenol were also calculated. The obtained results indicate that the catalytic hydrogenation of p-nitrophenol is a non-spontaneous and endothermic process. We have also investigated the effect of surfactants (NH4OH, FA, and N2) on the reaction performance, and consequently NH4OH and FA both slow down the reaction while N2 doesn't affect the reaction medium. Further, we calculated the rate constant for the hydrogenation of 2,4-dinitrophenol and 2,4,6-trinitrophenol. An array of nitroarenes were further reduced to extend the substrate scope at RT; high TOFs were observed. Besides, Pd&at;CCTP showed excellent reusability in hydrogenation reactions without evident performance falloff.
In Situ Synthesized Silica-Supported Co@N-Doped Carbon as Highly Efficient and Reusable Catalysts for Selective Reduction of Halogenated Nitroaromatics
Sheng, Yao,Wang, Xueguang,Yue, Shengnan,Cheng, Gonglin,Zou, Xiujing,Lu, Xionggang
, p. 4632 - 4641 (2020/07/30)
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.
Highly selective hydrogenation of halogenated nitroarenes over Ru/CN nanocomposites by: In situ pyrolysis
Yue, Shengnan,Wang, Xueguang,Li, Shaoting,Sheng, Yao,Zou, Xiujing,Lu, Xionggang,Zhang, Chunlei
, p. 11861 - 11869 (2020/07/28)
A highly chemoselective and recyclable ruthenium catalyst for the hydrogenation of halogenated nitroarenes has been prepared via the simple in situ calcination of a mixture of melamine, glucose and ruthenium trichloride. Superfine Ru particles (2.3 ± 0.3 nm) were obtained and highly dispersed in the nitrogen-doped carbon matrix. The Ru/CN catalyst smoothly transforms a variety of halogenated nitroarenes to the corresponding haloanilines with high intrinsic activity (e.g. TOF = 1333 h-1 for p-chloronitrobenzene) and selectivity of more than 99.6percent. Furthermore, through an analysis of the products in the reaction process, it was concluded that there are two parallel reaction pathways (a direct pathway and an indirect pathway) for the hydrogenation of aromatic nitro compounds over the Ru/CN catalyst, and the direct pathway was proved to be dominant in catalyzing the intermediates. This journal is
Iron oxide modified N-doped porous carbon derived from porous organic polymers as a highly-efficient catalyst for reduction of nitroarenes
Dong, Zhengping,Liu, Zhengtang,Lv, Jing
, (2020/10/27)
Fabrication of cost-effective non-noble metal-based catalysts is significant for heterogeneous catalysis. Here, we prepared a porous organic polymer (POP) through the facile condensation of p-phenylenediamine with ferrocene carboxaldehyde, and then the ferrocene-functionalized POP material was carbonized under inert atmosphere, obtaining the γ-Fe2O3 nanoparticles (NPs) modified N-doped porous carbon catalyst (γ-Fe2O3/NPC). Various characterizations (such as XRD, BET, TEM and XPS etc.) indicated that the obtained γ-Fe2O3/NPC catalyst exhibits unique structural properties with uniformly dispersed γ-Fe2O3 species, porous morphology, and N-doped defective amorphous carbon. The γ-Fe2O3/NPC catalyst shows excellent activity in the catalytic reduction of nitroarenes with hydrazine hydrate as reductant. The synergistic effect between γ-Fe2O3 NPs and N-doped porous carbon improve the hydrazine hydrate adsorption and activation for active hydrogen atoms production, which is beneficial for nitroarenes reduction. Moreover, the γ-Fe2O3/NPC catalyst could be easily recycled by using a magnet and reused without obviously loss of catalytic activity. Therefore, this work should provide a useful platform for designing and fabricating stable non-noble metal NPs based catalysts derived from POP materials that have potential for various catalytic applications.
Sustainable visible light assisted in situ hydrogenation via a magnesium-water system catalyzed by a Pd-g-C3N4 photocatalyst
Sharma, Priti,Sasson, Yoel
supporting information, p. 261 - 268 (2019/01/28)
A non-hazardous and relatively mild protocol was formulated for an effectual hydrogen generation process via a "magnesium-activated water" system with a Pd-g-C3N4 photocatalyst under visible light at room temperature. Water functions photochemically as a hydrogen donor without any external source with the Pd-g-C3N4 photocatalyst. The synthesized Pd-g-C3N4 photocatalyst is highly efficient under visible light for the selective reduction of a wide range of unsaturated derivatives and nitro compounds to afford excellent yields (>99%). The photocatalyst Pd-g-C3N4 could be easily recovered and reused for several runs without any deactivation during the photochemical hydrogen transfer reaction process.
Bi-functional catalyst of porous N-doped carbon with bimetallic FeCu for solvent-free resultant imines and hydrogenation of nitroarenes
Wang, Kaizhi,Gao, Wenbing,Jiang, Pengbo,Lan, Kai,Yang, Ming,Huang, Xiaokang,Ma, Lei,Niu, Fang,Li, Rong
, p. 43 - 53 (2019/01/08)
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.
Co-MOF-Derived Hierarchical Mesoporous Yolk-shell-structured Nanoreactor for the Catalytic Reduction of Nitroarenes with Hydrazine Hydrate
Yuan, Man,Zhang, Hongbo,Yang, Chen,Wang, Fanhao,Dong, Zhengping
, p. 3327 - 3338 (2019/07/04)
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.
