Hydrogenation Of Nitro Compounds Research Articles

Ni2MnAl Heusler Alloy Nanoparticles for Chemoselective Hydrogenation of Nitro Compounds

Despite immense interest for years in Heusler alloys as magnetoelastic materials, their application in heterogeneous catalysis has only recently been explored. We report the development of highly active, robust and magnetically separable Ni2MnAl Heusler alloy nanoparticles as a heterogeneous catalyst for hydrogenation of aliphatic and aromatic nitro compounds to the corresponding amines. The easily synthesizable Ni2MnAl nanoparticles are thermally and chemically robust and exhibited excellent chemoselectivity in the hydrogenation of a range of aliphatic and aromatic nitroarenes, including those bearing functional groups sensitive to reduction, such as alkene, bromo, iodo, carbonyl and cyano, yielding the respective functionalized amines in good yields. Moreover, this solid catalyst is magnetically separable from the reaction mixture and could be recycled and reused at least 10 times without any loss in catalytic activity. The mechanism of the Ni2MnAl Heusler alloy nanoparticles catalyzed nitro reduction was studied by various spectroscopy and control experiments and kinetics. Our work opens a new avenue of developing heterogeneous earth‐abundant metal catalysis for economic and environment‐friendly synthesis of fine chemicals owing to their straightforward synthesis and tunable composition from base‐metals and their diverse structure and properties with their high surface area, thermal and chemical stability, excellent chemoselectivity, magnetic separability and recyclability.

Recent Progress in Homogeneous Catalytic Hydrogenation of Nitro Compounds

Recent Progress in Homogeneous Catalytic Hydrogenation of Nitro Compounds

Synthesis of an MXene supported Co nanoparticle catalyst for efficient catalytic transfer hydrogenation of nitro compounds with formic acid

The developed 2.6% Co/MXene exhibited excellent catalytic performance for the catalytic transfer hydrogenation of readily available nitroarenes employing HCOOH, leading to the specific generation of essential and versatile formamides.

Protein–metal ion networks coated carbon matrix as a precursor: to construct carbon-supported Mo-based catalysts with highly exposed active sites for hydrogenation of nitro compounds

Protein–metal ion networks coated carbon matrices were employed as a precursor for preparing carbon-supported Mo-based catalysts with highly exposed active sites for nitro hydrogenation.

Highly Efficient Iron-Based Catalyst for Light-Driven Selective Hydrogenation of Nitroarenes.

Light-driven hydrogenation of nitro compounds to functionalized amines is of great importance yet a challenge for practical applications, which calls for the development of high-performance, nonprecious photocatalysts and efficient catalytic systems. Herein, we report a high-efficiency Fe3O4@TiO2 photocatalyst via a sol-gel and subsequent pyrolysis strategy, which exhibits desirable photothermal hydrogenation performance of nitro compounds to functionalized amines with the excellent selectivity of >90% exceeding those of the state-of-the-art heterogeneous photocatalysts. Our experimental results and theoretical calculations for the first time reveal that Fe3O4 is the major active phase, and the strong metal-support interaction between Fe3O4 and reducible TiO2 further leads to performance improvement, taking advantage of the enhanced photothermal effect and the improved adsorption for the reactant and hydrazine hydrate. Notably, a variety of halonitrobenzenes and pharmaceutical intermediates can be completely converted to functionalized amines with high selectivities, even in gram-scale reactions. This work provides a new insight into the rational design of nonprecious photo/thermo-catalysts for other catalytic reactions.

Interfacial nanoarchitectonics of nickel phosphide supported on activated carbon for transfer hydrogenation of nitroarenes under mild conditions

Metal phosphides are promising catalysts for hydrogenation reactions due to their unique ability to generate active hydrogen species which are essential for desired reactions. In this work, the hydrogenation potential of nickel phosphide (Ni2P) is explored for the transfer hydrogenation of aromatic nitro compounds using hydrazine hydrate as hydrogen source. The Ni2P was supported on activated carbon (AC) to facilitate highly exposed active reaction sites. The as-synthesized Ni2P-AC catalyst showed excellent catalytic potential for the hydrogenation of nitro compounds to corresponding amines with 100% conversion efficiency and resulted in excellent yields. The reaction conditions were optimized by varying different reaction parameters, such as time, temperature, solvents, catalyst amount and hydrogen sources. The developed reaction protocol is highly selective for nitro compounds having reduction susceptible functional groups like -Cl, -Br, –CHO, etc. The structure–activity relationship of the Ni2P-AC was also examined which suggested that both acidic and basic sites present in Ni2P-AC catalyst plays crucial role in hydrogenation reaction. Besides, an in-depth insight into the reaction mechanism illustrates that the reaction proceeds via N-phenyl hydroxylamine as the reaction intermediate. In addition, decent recyclability and stability of Ni2P-AC catalyst demonstrates its highly versatile nature for potential large-scale applications. The use of highly efficient Ni2P-AC catalyst for hydrogenation reactions can lead the way towards sustainable and effective industrial organic catalysis.

Recent advances in β‐cyclodextrin‐based catalysts for reducing toxic nitroaromatic: An overview

Regarding the incremental shortage of water resources, wastewater treatment is essential for guarding the ecosystem and the sufficient usage of water resources. Freshwater, a vital item of life for humans and animals, is in danger because of the existence of destructive pollutants, such as p‐nitrophenol (p‐NP), and organic azo dyes, leading to water pollution. Among environmental pollution, water pollution has been recognized as one of the important threat agents in charge of many illnesses in humans. Nitrophenols contain high stability and solubility in water, which causes health risks. It is essential to change these harmful chemicals into healthy materials to have a safe life on the globe. Nitro compounds obtained from industrial wastewater are a severe threat to human being health and living organisms. Hence, designing green strategies and environment‐friendly catalysts to reduce toxic contaminants such as nitro compounds and dyes is a considerable challenge. One technique to overcome this crisis is the catalytic hydrogenation of nitro compounds to the amines, which are invaluable and non‐toxic materials. Reducing nitroarenes can be synthesized the amines, vital intermediates in organic and biological chemistry. Designing green strategies in nitro reduction processes for synthetic organic chemists is a great challenge. The nitroarene reduction reaction is a very efficient, reliable, and environmentally friendly method for synthesizing amines. Cyclodextrin (CD) can be applied as an effective catalyst in many aqueous organic reactions. Their derivatives have exhibited outstanding performance in water‐mediated organic synthesis and are now of ongoing attraction to many scientists in various fields. CDs show better catalytic activity and selectivity due to their particular geometry and structural interactions. CDs catalyzed reactions have been getting significant attention recently due to their low toxicity, biodegradability, economically and eco‐friendly behavior. Many reports are available in the literature on CDs material considered promising catalysts in reducing nitro compounds. This review article focuses on the use of β‐CD catalyst systems as valuable catalysts in the hydrogenation of nitroarenes and overviews articles up to 2023.

Construction of Highly Active and Selective Molecular Imprinting Catalyst for Hydrogenation.

Surface molecular imprinting (MI) is one of the most efficient techniques to improve selectivity in a catalytic reaction. Heretofore, a prerequisite to fabricating selective catalysts by MI strategies is to sacrifice the number of surface-active sites, leading to a remarkable decrease of activity. Thus, it is highly desirable to design molecular imprinting catalysts (MICs) in which both the catalytic activity and selectivity are significantly enhanced. Herein, a series of MICs are prepared by sequentially adsorbing imprinting molecules (nitro compounds, N) and imprinting ligand (1,10-phenanthroline, L) over the copper surface of Cu/Al2O3. The resulting Cu/Al2O3-N-L MICs not only offer promoted catalytic selectivity but also enhance catalytic activity for nitro compounds hydrogenation by an creating imprinting cavity derived from the presorption of N and forming new active Cu-N sites at the interface of the copper sites and L. Characterizations by means of various experimental investigations and DFT calculations disclose that the molecular imprinting effect (promoted activity and selectivity) originates from the formation of new active Cu-N sites and precise imprinting cavities, endowing promoted catalytic selectivity and activity on the hydrogenation of nitro compounds.

Heterogeneous V2O5/TiO2-Mediated Photocatalytic Reduction of Nitro Compounds to the Corresponding Amines under Visible Light.

The hydrogenation of nitro compounds to their corresponding amines is developed using a heterogeneous and recyclable catalyst (V2O5/TiO2) under irradiation of blue LED (9 W) at ambient temperature. Hydrazine hydrate is used as a reductant and ethanol is used as a solvent, facilitating green, sustainable, low-cost production. The synthesis of 32 (hetero)arylamines and their pharmaceutically relevant molecules (five) are described. Significant features of the protocol include catalyst recyclability, green solvent, ambient temperature, and gram-scale reactions. Among the other aspects studied are 1H-NMR-assisted reaction progress monitoring, control experiments for mechanistic studies, protocol applications, and recyclability studies. Furthermore, the developed protocol enabled wide functional group tolerance, chemo-selectivity, high yield, and low-cost, sustainable, and environmentally benign synthesis.

Cobalt-Doped g-C3N4 Nanosheets for One-Pot Synthesis of Imines under Mild Conditions

The traditional synthesis methods of imines are limited by expensive catalysts, harsh reaction conditions, and low atomic efficiency. The one-pot synthesis of imines using nitrobenzene and benzaldehyde is a promising reaction path. Transition metal catalytic transfer hydrogenation offers advantages in terms of safety. It has attracted the attention of industrial production and academia as an alternative to conventional hydrogenation processes. Herein, we report an environmentally friendly Co/g–C3N4 nanocatalyst that uses inexpensive cobalt as the fundamental source of feedstock; formic acid is applied as the hydrogen donor, and the yield of the synthesis method can reach 96% under mild conditions. Besides, the catalyst proved to be stable and efficient despite five successive cycles of testing. Moreover, the excellent catalytic activity was demonstrated to be derived from the Co–Nx site based on the mechanistic analysis and characterization. For this work, a pathway will be developed to produce transfer hydrogenation of nitro compounds.

Iron-Based Active Sites Encapsulated in Carbon Nanotubes for an Efficient Hydride Process

Selective and efficient catalytic hydrogenation of aromatic nitro compounds with multiple groups into target amines under mild conditions is highly desirable yet fairly challenging. Herein, we report a novel iron-based catalyst, which has metal nanoparticles (NPs) encapsulated in porous N-doped carbon nanotubes (NCT). The experimental and density functional theory results reveal that the NCT-supported porous structure provides the metal nanoparticles with more accessible active sites, leading to the Fe/Fe5C2@NCT-800 catalyst to show extremely high activity, chemoselectivity, and stability toward the hydrogenation of nitro compounds, affording full conversion within 0.2–0.3 h under room temperature.

Boosting Chemoselective Hydrogenation of Nitroaromatic via Synergy of Hydrogen Spillover and Preferential Adsorption on Magnetically Recoverable Pt@Fe2 O3.

It is highly desired but challenging to design high performance catalyst for selective hydrogenation of nitro compounds into amino compounds. Herein, a boosting chemoselective hydrogenation strategy on Pt@Fe2 O3 is proposed with gradient oxygen vacancy by synergy of hydrogen spillover and preferential adsorption. Experimental and theoretical investigations reveal that the nitro is preferentially adsorbed onto oxygen vacancy of Pt@Fe2 O3 , meanwhile, the H2 dissociated on Pt nanoparticles and then spillover to approach the nitro for selective hydrogenation (>99% conversion of 4-nitrostyrene, > 99% selectivity of 4-aminostyrene, TOF of 2351h-1 ). Moreover, the iron oxide support endows the catalyst magnetic retrievability. This high activity, selectivity, and easy recovery strategy provide a promising avenue for selective hydrogenation catalysis of various nitroaromatic.

Chemoselective Hydrogenation of Nitro Compounds by MoS2 via Introduction of Independent Active Hydrogen-Donating Sites

Chemoselective Hydrogenation of Nitro Compounds by MoS₂ via Introduction of Independent Active Hydrogen-Donating Sites

Site-Isolated Cobalt Complex on Porous Carbon as a Catalyst for Hydrogenation of Nitro Compounds

Site-Isolated Cobalt Complex on Porous Carbon as a Catalyst for Hydrogenation of Nitro Compounds

Solvent-free synthesis of Co@NC catalyst with Co—N species as active sites for chemoselective hydrogenation of nitro compounds

Metal-organic frameworks (MOFs) derived Co-based catalysts have received extensive attention in the chemoselective hydrogenation of nitroarenes, while they usually require a lot of solvent during the synthesis and identification of active species. This study explores a solid-phase synthesis strategy to obtain MOF precursors without using any solvent, which is then foamed and pyrolyzed to synthesize the Co@NC-X catalyst. It was found that a nitrogen-doped graphene shell can well encapsulate the Co nanoparticles. The resulting catalyst, which was pyrolyzed at 800°C, exhibited ~100% conversion for the hydrogenation of 3-nitrostyrene and >99% selectivity to 3-vinylaniline. This catalyst also showed excellent stability and good substrate universality for the hydrogenation of extensive substituted nitroarenes. Various characterizations revealed a positive relationship between the catalytic performance and the content of Co—N species tuned by pyrolysis temperature. This work provides a novel and green strategy to design an efficient Co-based catalyst for chemoselective hydrogenation.

High-density atomically dispersed CoNx catalysts supported on nitrogen-doped mesoporous carbon materials for efficient hydrogenation of nitro compounds

Carbon supported atomically dispersed transition metal–nitrogen (MNx) catalysts are promising for catalysis. Synthesis of such catalysts with high densities of MNx sites is an important task. In this work, a facile and scalable method by combining freeze drying and hard templating is presented for the synthesis of N-doped mesoporous carbon supported high-density and exclusive CoNx sites (denoted as CoNx-NMCs). The influences of the drying method (freeze drying and regular drying) on the aggregation of the silica pore forming agent, the precursor and metal species and the properties and performances of the resulted catalysts are investigated. The strong Co2+/histidine and silica/histidine interactions and the homogeneous distribution of the SiO2 nanoparticles for precursor physical isolation are essential to inhibit metal aggregation, sustain N dopant and generate high densities of CoNx sites. The CoNx-OMCs possess high surface areas (440–630 m2/g), uniform mesopores (~ 7 nm), high N contents (2.54–17.84 wt%) and abundant CoNx sites with high single cobalt atom loadings up to 1.7 wt%. The representative catalyst delivers outstanding catalytic performances for hydrogenation of a series of nitro compounds into amines with excellent conversions and selectivities and a high stability with H2 as the reducing agent and water as the solvent. A series of control experimental results clearly reveal the critical role of the CoNx sites for the chemoselective hydrogenation and clarify the influences of the properties of the catalysts on their performances. The work may provide a general approach and some insight for the development of atomically dispersed MNx catalysts with a high metal atom utilization efficiency for the purpose of various catalytic applications.

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Atomically Dispersed Co–S–N Active Sites Anchored on Hierarchically Porous Carbon for Efficient Catalytic Hydrogenation of Nitro Compounds

Atomically Dispersed Co–S–N Active Sites Anchored on Hierarchically Porous Carbon for Efficient Catalytic Hydrogenation of Nitro Compounds

Pd on thermo-responsive composite of silica-coated carbon nanotube and 1-vinyl-3-butylimidazolium-based ionic liquid copolymers as an efficient catalyst for hydrogenation of nitro compounds

In this work, an ionic liquid-containing thermo-responsive heterogeneous catalyst with utility for promoting hydrogenation of nitro-compounds in aqueous media is developed. To prepare the catalyst, silica-coated carbon nanotubes were synthesized and vinyl-functionalized. The resulted compound was then polymerized with 1-viny-3-butylimidazolium bromide and N-isopropylacrylamide. The obtained ionic liquid-containing thermo-responsive composite was palladated via wet-impregnation method to give the final catalyst. Study of the performance of the catalyst confirmed high catalytic activity of the catalyst at temperature above the lower critical solution temperature. Furthermore, the catalyst was highly recyclable and showed negligible Pd leaching upon recycling. Broad substrate scope and selectivity of the catalyst towards reduction of nitro functionality were also confirmed. Furthermore, hot filtration test implied the heterogeneous nature of the catalysis. The comparison of the activity of Pd/CNT-P with some control catalysts approved the importance of hybridization of P and CNT and the presence of ionic liquid for the catalytic activity.

Pd on imidazolium ionic liquid modified halloysite: A potent catalyst for the hydrogenation of nitro-compounds under mild reaction condition

Cl-functionalized halloysite nanoclay was modified by multi imidazolium ionic liquids through successive reactions with imidazole, epichlorohydrin, tris(2-aminoethyl)amine and the as-prepared epoxide-functionalized imidazolium ionic liquid. The resultant compound was used as a support for the stabilization of Pd nanoparticles to furnish a heterogeneous catalyst for the hydrogenation of nitro-compounds in aqueous media. Investigation of the reaction variables confirmed that use of scant amount of the catalyst at ambient temperature and hydrogen pressure of 1 bar led to the formation of the hydrogenated products in high yields. Moreover, hydrogenation of the nitro compounds with carbonyl groups confirmed high selectivity of the catalyst towards hydrogenation of nitro group. Hot filtration test also demonstrated the true heterogeneous nature of the catalysis and recycling experiments indicated that the catalyst could be recovered and recycled for five successive reaction runs with slight Pd leaching and loss of the activity.