626-01-7Relevant articles and documents
Nickel–Ruthenium Bimetallic Species on Hydrotalcite Support: A Potential Hydrogenation Catalyst
Ahammed, Shabas,Ganesh, V.,Ramachandran, Arya,Sakthivel, A.,Sreenavya, A.
, (2021)
Nickel–ruthenium loaded on magnesium–aluminium hydrotalcite materials were prepared by a post-synthetic method. The textural and physicochemical properties of the materials were systematically characterised by Fourier transform infra-red (FT–IR), powder X-ray diffraction (XRD), scanning electron microscope (SEM), nitrogen sorption, and X-ray photoelectron spectroscopy (XPS) analysis. The uniform distribution of bimetallic Ni-Ru on hydrotalcite support was evident from the powder XRD and HRTEM analysis of the used catalysts. The hydrogen temperature-programmed reduction profile reveals strong adsorption of hydrogen on the surface of the catalysts. The resultant materials show promising catalytic activity for nitrobenzene reduction under ambient reaction conditions. The formation of metallic nickel and ruthenium on the surface of hydrotalcite under the reaction conditions was evident through powder XRD analysis of the sample obtained under reaction condition. The reaction showed first order kinetics with respect to nitrobenzene. Furthermore, the catalytic activity remained intact for several cycles, and the catalysts also showed promising activity for the reduction of several substituted nitroarene molecules. Graphical Abstract: [Figure not available: see fulltext.].
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.
In situcreation of multi-metallic species inside porous silicate materials with tunable catalytic properties
Liu, Yang-Yang,Wu, Chuan-De,Zhan, Guo-Peng
supporting information, p. 6185 - 6188 (2021/06/30)
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.
NaI/PPh3-Mediated Photochemical Reduction and Amination of Nitroarenes
Qu, Zhonghua,Chen, Xing,Zhong, Shuai,Deng, Guo-Jun,Huang, Huawen
supporting information, p. 5349 - 5353 (2021/07/21)
A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 was found to enable highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (Cl, Br, and even I), aldehyde, ketone, carboxyl, and cyano. Moreover, the photoredox catalysis with NaI and stoichiometric PPh3 provides also an alternative entry to Cadogan-type reductive amination when o-nitrobiarenes were used.
A suitable modified palladium immobilized on imidazolium supported ionic liquid catalysed transfer hydrogenation of nitroarenes
Atheeswari, Alagudurai,Kanimozhi, Nallusamy,Karthikeyan, Parasuraman,Shanmugapriya, Ramasamy
, (2021/06/28)
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.
Microwave-assisted reduction of aromatic nitro compounds with novel oxo-rhenium complexes
Blacque, Olivier,Grieco, Gabriele
, (2021/09/16)
The reduction of several aromatic nitro compounds to amines by means of the two novel catalytic systems ([IMes]2ReOBr3)/PhSiH3 and ([Py]3ReNOBr2)/PhSiH3 under microwave irradiation is here reported. These two systems were able to perform the reduction of nitro groups with higher TON and TOF when compared with previously reported systems based on oxo-rhenium core under standard heating, although they showed a lesser broad reaction scope compared with the known systems.
Tuning acylthiourea ligands in Ru(II) catalysts for altering the reactivity and chemoselectivity of transfer hydrogenation reactions, and synthesis of 3-isopropoxy-1H-indole through a new synthetic approach
Sathishkumar, Pushpanathan N.,Prabha, Padinhattath Sachind,Bhuvanesh, Nattamai S.P.,Karvembu, Ramasamy
, (2020/01/09)
Ru(II)-p-cymene complexes (1–3) containing picolyl based pseudo-acylthiourea ligands (L1-L3) were synthesized and characterized. The crystallographic study confirmed the molecular structures of all the ligands (L1-L3) and complex 3. The catalytic activity of the complexes was tested mainly towards TH of carbonyl compounds and nitroarenes. The influence of steric and electronic effects of the ligands on the chemoselectivity and reactivity were reported. The catalytic activity was enhanced and chemoselectivity was switched after tuning the ligands in the catalysts, compared to their corresponding unmodified Ru(II)-p-cymene complexes. The catalysis was extended to a broad range of substrates including some challenging systems like furfural, benzoylpyridine, benzoquinone, chromanone, etc. The strategy of tuning the bifunctional ligands in the catalysts for effective and selective catalysis worked nicely. Further, the catalysis was extended to one pot synthesis of 3-isopropoxyindole from 2-nitrocinnamaldehyde, the first synthetic route similar to Baeyer Emmerling indole synthesis. All the catalytic experiments exhibited high conversion and selectivity.
In situ-formed cobalt embedded into N-doped carbon as highly efficient and selective catalysts for the hydrogenation of halogenated nitrobenzenes under mild conditions
Cao, Yueling,Liu, Kangkai,Wu, Chen,Zhang, Hepeng,Zhang, Qiuyu
, (2020/01/28)
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.
Direct Hydrogenation of Nitroaromatics at Room Temperature Catalyzed by Magnetically Recoverable Cu@Fe2O3 Nanoparticles
Borah, Biraj Jyoti,Bharali, Pankaj
, (2020/05/18)
Metal embedded in metal oxide nanoparticles are active as catalyst in plethora of industrially important reactions. Herein, embedded Cu@Fe2O3 nanoparticles was synthesized via a one step hydrothermal strategy which selectively catalyzes the hydrogenation of diverse nitroaromatics in H2O at room temperature. The remarkable catalytic performance is due to the successful hybridization of metallic Cu and Fe2O3 which in turn allows easy electroflipping between various oxidation states of Cu and Fe. Azo- and azoxy-compounds are not formed during the catalyzed process. This evidently establish that the hydrogenation of nitroaromatics proceeds via direct route with >99percent selectivity to the corresponding anilines.
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.
