Hydrogenation Of Nitroarenes Research Articles

Molybdenum trioxide as a newer diversified economic catalyst for the transformation of nitroarenes to arylamine and 5-substituted-1H-tetrazole.

The present work has developed a straightforward, gentle, and effective approach for synthesizing arylamines and 5-substituted-1H-tetrazole derivatives, and among the two tested catalysts, molybdenum trioxide (MoO3) proved to be highly effective. The selective hydrogenation of nitroarenes to arylamines presents a significant challenge due to the complex reaction mechanism and the competitive hydrogenation of other reducible functional groups. It facilitated the transfer hydrogenation of nitrobenzene using hydrazine hydrate-produced amino compounds and enabled the [3 + 2] cycloaddition of sodium azide with aromatic nitriles to yield 5-substituted-1H-tetrazoles. The structure of compound 5-(4-bromophenyl)-1H-tetrazole (5k) was verified through single-crystal X-ray analysis, and the calculation of Green Chemistry Metrics showed the optimal range. Notably, the MoO3 catalyst can be reutilized for up to seven cycles with minimal loss of effectiveness. These attributes make molybdenum trioxide particularly attractive for industrial applications. This methodology offers several advantages over traditional synthetic methods.

Bifunctional Fe2O3 catalyst for the hydrogenation and transfer hydrogenation of nitroarenes

Bifunctional Fe2O3 could activate H2 and N2H4·H2O to reduce nitrobenzene, in which the –NO2 group was involved in the hydrogenation process.

Synergistic enhancement of electrocatalytic nitroarene hydrogenation over Mo2C@MoS2 heteronanorods with dual active-sites.

Electrocatalytic hydrogenation (ECH) enables the sustainable production of chemicals under ambient conditions, in which catalysts catering for the different chemisorption of reactants/intermediates are desired but still challenging. Here, Mo2C@MoS2 heteronanorods with dual active-sites are developed to accomplish efficient nitroarene ECH according to our theoretical prediction that the binding of atomic H and nitro substrates would be synergistically strengthened on Mo2C-MoS2 interfaces. They afford high faradaic efficiency (>85%), yield (>78%) and selectivity (>99%) for the reduction of 4-nitrostyrene (4-NS) to 4-vinylaniline (4-VA) in neutral electrolytes, outperforming not only the single-component counterparts of Mo2C nanorods and MoS2 nanosheets, but also recently reported noble-metals. Accordingly, in situ Raman spectroscopy combined with electrochemical tests clarifies the rapid ECH of 4-NS on Mo2C-MoS2 interfaces due to the facilitated elementary steps, quickly refreshing active sites for continuous electrocatalysis. Mo2C@MoS2 further confirms efficient and selective ECH toward functional anilines with other well-retained reducible groups in wide substrate scope, underscoring the promise of dual-site engineering for exploring catalysts.

Highly dispersed platinum and phosphomolybdic acid (PMo) on the UiO-66 metal–organic framework (MOF) for highly efficient and selective hydrogenation of nitroaromatics

Pt-PMo@UiO-66 (0.32 wt% Pt) shows the highest catalytic activity and selectivity to one –NO2 hydrogenation in nitroarene hydrogenation due to its novel structure and synergism.

Catalysis for the hydrogenation of nitroaromatics by highly dispersed palladium nanoparticles anchored on a resorcin[4]arene-based metal–organic dimer containing amino groups

A new family of resorcin[4]arene-based metal–organic dimers (1–9) were self-assembled, and the catalyst Pd@2 displayed efficient catalytic performance for nitroarene hydrogenation.

Electron-rich Pt anchored on covalent triazine frameworks for the selective hydrogenation of halogenated nitrobenzenes

Ultrafine Pt nanoparticles were successfully anchored on a polyimide-based covalent triazine framework for the selective hydrogenation of halogenated nitrobenzenes and tandem hydrogenation-coupling reaction to halogenated secondary amines.

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.

Copper-Catalyzed Continuous-Flow Transfer Hydrogenation of Nitroarenes to Anilines: A Scalable and Reliable Protocol.

A robust supported catalyst that is made up of copper nanoparticles on Celite has been successfully prepared for the selective transfer hydrogenation of aromatic nitrobenzenes to anilines under continuous flow. The method is efficient and environmentally benign thanks to the absence of hydrogen gas and precious metals. Long-term stability studies show that the catalytic system is able to achieve very high nitrobenzene conversion (>99%) when working for up to 145 h. The versatility of the transfer hydrogenation system has been tested using representative examples of nitroarenes, with moderate-to-excellent yields being obtained. The packed bed reactor (PBR) permits the use of a setup that can provide products via simple isolation by SPE without the need for further purification. The recovery and reuse of either EG or the ion-exchange resin leads to consistent waste reduction; therefore, E-factor distribution analysis has highlighted the environmental efficiency of this synthetic protocol.

Doped activated carbons obtained from nitrogen and sulfur-containing polymers as metal-free catalysts for application in nitroarenes hydrogenation

Activated carbons doped with nitrogen and/or sulfur have been obtained by pyrolysis followed of steam activation of a sulfur containing polymer (polythiophene) and two nitrogen-containing polymers (polyaniline and polypyrrole). These polymers were synthesized by oxidative chemical polymerization in aqueous media of their corresponding monomers.The influence of the steam activation on the textural properties and surface chemistry of the carbons has been evaluated and their catalytic activity has been determined in the hydrogenation reaction of 1-chloro-4-nitrobenzene. The degree of conversion in the reaction depends on the development of adequate porosity in the activated carbon (which is determined by the activation conditions) together with the presence of heteroatoms that act as active catalytic sites, with S showing considerably greater effectiveness than N. A compromise between an acceptable level of doping with sulfur and an adequate porosity is necessary, which has been achieved in a carbon obtained from polythiophene pyrolyzed at 900 °C and steam activated at 800 °C for 4 h, with a specific surface area of 742 m2/g and S content of 1.71 at%.

Total Structure, Structural Transformation and Catalytic Hydrogenation of [Cu41 (SC6 H3 F2 )15 Cl3 (P(PhF)3 )6 (H)25 ]2- Constructed from Twisted Cu13 Units.

Herein, a remarkable achievement in the synthesis and characterization of an atomically precise copper-hydride nanocluster, [Cu41 (SC6 H3 F2 )15 Cl3 (P(PhF)3 )6 (H)25 ]2- via a mild one-pot reaction is presented. Through X-ray crystallography analysis, it is revealed that [Cu41 (SC6 H3 F2 )15 Cl3 (P(PhF)3 )6 (H)25 ]2- exhibits a unique shell-core-shell structure. The inner Cu29 kernel is composed of three twisted Cu13 units, connected through Cu4 face sharing. Surrounding the metal core, two Cu6 metal shells, resembling a protective sandwich structure are observed. This arrangement, along with intracluster π···π interactions and intercluster C─H···F─C interactions, contributes to the enhanced stability of [Cu41 (SC6 H3 F2 )15 Cl3 (P(PhF)3 )6 (H)25 ]2- . The presence, number, and location of hydrides within the nanocluster are established through a combination of experimental and density functional theory investigations. Notably, the addition of a phosphine ligand triggers a fascinating nanocluster-to-nanocluster transformation in [Cu41 (SC6 H3 F2 )15 Cl3 (P(PhF)3 )6 (H)25 ]2- , resulting in the generation of two nanoclusters, [Cu14 (SC6 H3 F2 )3 (PPh3 )8 H10 ]+ and [Cu13 (SC6 H3 F2 )3 (P(PhF)3 )7 H10 ]0 . Furthermore, it is demonstrated that [Cu41 (SC6 H3 F2 )15 Cl3 (P(PhF)3 )6 (H)25 ]2- exhibits catalytic activity in the hydrogenation of nitroarenes. This intriguing nanocluster provides a unique opportunity to explore the assembly of M13 units, similar to other coinage metal nanoclusters, and investigate the nanocluster-to-nanocluster transformation in phosphine and thiol ligand co-protected copper nanoclusters.

A general and robust Ni-based nanocatalyst for selective hydrogenation reactions at low temperature and pressure.

Catalytic hydrogenations are important and widely applied processes for the reduction of organic compounds both in academic laboratories and in industry. To perform these reactions in sustainable and practical manner, the development and applicability of non-noble metal-based heterogeneous catalysts is crucial. Here, we report highly active and air-stable nickel nanoparticles supported on mesoporous silica (MCM-41) as a general and selective hydrogenation catalyst. This catalytic system allows for the hydrogenation of carbonyl compounds, nitroarenes, N-heterocycles, and unsaturated carbon─carbon bonds in good to excellent selectivity under very mild conditions (room temperature to 80°C, 2 to 10 bar H2). Furthermore, the optimal nickel/meso-silicon dioxide catalyst is reusable (4 cycles) without loss of its catalytic activity.

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.

Hydrogenation of Nitroarenes by Onsite-Generated Surface Hydroxyl from Water

Hydrogenation of Nitroarenes by Onsite-Generated Surface Hydroxyl from Water

Ethanol as hydrogen donor: An efficient transfer hydrogenation of aldehydes, ketones, and nitroarenes with H-bonded Ru(II)-N-heterocyclic iminium complex

Isopropanol and formic acid are predominantly utilized as hydrogen sources in catalytic transfer hydrogenation reactions. However, the utilization of primary alcohols in such reactions has been sparsely documented, with only a limited number of reports available. In this article, we hereby present findings that underscore the prospective application of ecologically sustainable and economically viable ethanol, alongside a ruthenium(II) catalyst that exhibits remarkable resilience in the presence of moisture and oxygen. The air-stable Ru(II) complex (I) has been synthesized by non-covalently interacting anionic Ru(p-cymene)Cl3 and 1,3-diisopropyl-1H-perimidin-2(3H)-iminium (LH2+). The compound was subjected to experimental evaluation to conduct transfer hydrogenation reactions on aldehydes, ketones, and nitroarenes. The process entailed the utilization of ethanol, a hydrogen source that is both economically advantageous and ecologically benign. The hydrogen bond interaction existing between the Ru(p-cymene)Cl3 and LH2+ species plays a crucial in facilitating the exceptional catalytic efficiency exhibited by the Ru(II) complex (I). The reaction exhibits a wide range of substrate compatibility, enabling the hydrogenation of ketones, aldehydes, and nitroarenes. The results obtained from the control experiments have provided evidence for the formation of Ru − H species. A plausible mechanism has been hypothesized, relying on stoichiometric investigations.

Biosynthesis of silver nanocatalyst and its application for the efficient hydrogenation of nitroarenes

The utilization of plant extracts for the synthesis of silver nanoparticles (Ag-NPs) has attracted attention from all over the world due to its unique physicochemical characteristics and significance in the field of environment. Here, Nepal pepper fruit extract was successfully employed to synthesize Ag-NPs. As obtained, Nepal pepper-mediated Ag-NPs were employed for the catalytic conversion of nitroarenes including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), and 2,4,6-trinitrophenol (2,4,6-TNP), into their corresponding amino derivatives using sodium borohydride (NaBH4). The Ag-NPs were analyzed using UV–visible (UV-Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-rays (EDX), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), X-rays Diffraction (XRD), and Zeta potential. TEM micrographs revealed the prepared Ag-NPs were predominantly spherical, with an average diameter of 13.9 nm. DLS and zeta potential studies showed stable small-size Ag-NPs of an average size of 6.8 nm. Ag-NPs elucidate outstanding reduction efficiency against 4-NP, 2-NP, 2-NA, and 2,4,6-TNP with rate constants of 1.71 × 10−3 s−1, 2.32 × 10−3 s−1, 2.88 × 10−3 s−1, and 1.54 × 10−3 s−1, respectively. Additionally, stability and reusability of Ag-NPs revealed stability for up to 15 days and excellent recyclability with small activity loss. This study constittutes an environmentally friendly approach for the synthesis of Ag-NP nanoparticles and their applications in improved organic chemical reduction rates and transformations.

Ruthenium(III) acyl thiourea complex: A catalyst for transfer hydrogenation of nitroarenes

The complex of ruthenium (III) ([RuCl2(PPh3)2BTU], 1) was prepared by reacting the acylthiourea ligand with a ruthenium salt ([RuCl2(PPh3)3]), and has been thoroughly characterised using various analytical techniques such as elemental analysis, magnetic susceptibility, UV–Vis, 1H NMR and single-crystal X-ray diffraction. The crystal packing of 1 has been found to be stabilised by intramolecular and intermolecular hydrogen bonding interactions, as well as CH⋅⋅⋅π contacts, namely C9-H9A⋅⋅⋅Cg(5), C12-H12A⋅⋅⋅Cg(4) and C45-H45⋅⋅⋅Cg(3), which play a crucial role in determining the overall supramolecular crystal structure of the compound. Hirshfeld surface analysis and 2D fingerprint analysis of 1 revealed that the compound was stabilised by various intermolecular interactions, including CH⋯C and CH⋯Cl interactions, with intermolecular H⋅⋅⋅H (54.9 %), C⋅⋅⋅H/H⋅⋅⋅C (23.6 %) and Cl⋅⋅⋅H/H⋅⋅⋅Cl (19.0 %) interactions being more prominent than other types of interactions. Furthermore, the conversion of nitroarenes to their corresponding aniline compounds was studied at different time intervals in ethanol at 50 °C in the presence of NaBH4. Examination of different nitro substrates revealed that 1 was a remarkable catalyst for the catalytic reduction of nitroarenes (0.01 mol of catalyst, >99 yield).

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.

Catalytic Hydrogenation of Nitroarenes over Ag33 Nanoclusters: The Ligand Effect.

Using ligand-protected metallic nanoclusters with atomic precision as catalysts and elucidating its ligand effect in the catalysis are the prerequisites to deepen the structure-catalysis relationship of nanoclusters at the molecular level. Herein, a series of Ag33 nanoclusters protected with different thiolate ligands (2-phenylethanethiol, 4-chlorobenzyl mercaptan, and 4-methoxybenzyl mercaptan as precursors) were synthesized and used as heterogeneous catalysts for the conversion of nitroarenes to arylamine with NaBH4 as reductant. The obtained nanoclusters exhibited ligand-dependent catalytic activity, with benzyl thiolate ligands distinctly superior to the phenethyl thiolate ligands. DFT calculations revealed that the ligand regulated catalytic activity of the nanoclusters was ascribed to the H-π and π-π interactions between the ligands and the substrates, owing to the presence of phenyl rings in these structures. This work highlighted the importance of the ligands on the metallic nanoclusters in catalysis and provides a strategy to regulate the catalytic activity by utilizing weak interactions between the catalysts and the substrates.

Transfer Hydrogenation of Azoarenes and Nitroarenes Using Co, Supported on N-Doped Porous Carbon

Transfer Hydrogenation of Azoarenes and Nitroarenes Using Co, Supported on N-Doped Porous Carbon

Preparation of magnetic biochar functionalized by polyvinyl imidazole and palladium nanoparticles for the catalysis of nitroarenes hydrogenation and Sonogashira reaction

Catalysts are essential materials in biotechnology, medicine, industry, and chemistry. On the other hand, recycling and using waste materials is important in economic efficiency and green chemistry. Thus, biochar was prepared from the stem and roots of the Spear Thistle to recover waste. After magnetizing the biochar, its surface was modified with polyvinyl imidazole. Finally, this modified biochar was decorated with Pd nanoparticles and used as a selective and recyclable nanocatalyst in the hydrogenation of nitroarenes and the Sonogashira reaction. The structure of this organic–inorganic nanocatalyst has been characterized by FESEM-EDS, XRD, FT-IR, TEM, and VSM techniques. In the hydrogenation reaction with the amount of 30 mg of nanocatalyst, the temperature of 50 °C in the water solvent, the reaction efficiency reached 99% for 30 min. In addition, under optimal conditions for the Sonogashira reaction: 1.0 mmol iodobenzene, 1.2 mmol phenylacetylene, 20 mg MBC-PVIm/Pd, 2 mmol K2CO3 in H2O at 50 C for 15 min, the reaction efficiency reached 95%. The recyclability of magnetic nanocatalysts was investigated and recognized this nanocatalyst can be used several times without notable loss of its activity.