Reduction Of Aromatic Nitro Compounds Research Articles

Fabrication of CdIn2S4/ZnS S-scheme heterojunction via in-situ phase transformation for boosting photocatalytic conversion of organic compounds

Developing efficient photocatalysts is one of green and low cost tactic for addressing the environmental deterioration and energy crisis. Therefore, it remains a fantastic and important strategy to design an efficient junction between different semiconductors for harvesting solar light, boosting the redox capability. Herein, the fabrication of ZnS in situ decorated CdIn2S4 (referred to as CIS-Zx) were prepared by converting ZnS particles on Cd2In4S surface by a facile cation exchange method during solvothermal synthesis. According to a series of PEC measurements and DFT calculations, the bending of band edge as well as the establishing of built-in electric field in the interface of CIS/ZnS heterojunction were concluded, causing the formation of in-situ S-scheme heterojunctions in CdIn2S4/ZnS. The in-situ S-scheme heterojunctions can effectively ameliorate the migration behaviors of photo-generated charges. Compared with pure CdInS4, ZnS and physically mixed CdIn2S4/ZnS, the CIS-Zxin-situ S-scheme heterojunction exhibits efficient photocatalytic activity and stability in the selective reduction of aromatic nitro compounds and oxidation of aromatic alcohols, it is hoped that this work will open up a new avenue for innovative applications of in-situ S-scheme heterojunctions.

Ag nanoparticles on arginine-cyanoguanidine functionalized magnetic g-C3N4: A catalyst for nitroaromatic hydrogenation and regioselective click reactions

This study describes the development of a novel hybrid nanocatalyst that was obtained by doping magnetic g-C3N4 with Ag nanoparticles and modifying it with arginine and cyanoguanidine (Ag@Fe3O4-g-C3N4-Arg-CG). Comprehensive characterization of the nanocatalyst using techniques such as FTIR, XRD, SEM, and TGA confirmed its structural and morphological properties. The catalytic efficiency of the synthesized nanostructure was evaluated in two key reactions: the reduction of nitroaromatic compounds and a click reaction for 1,2,3-triazole synthesis. The results demonstrate that Ag@Fe3O4-g-C3N4-Arg-CG effectively reduced various nitroaromatic compounds to substituted anilines at room temperature using NaBH4 as the reducing agent. Nitrobenzene reduction did not proceed in aprotic solvents such as acetonitrile, CH2Cl2, and dimethylformamide, whereas it exhibited a high reaction yield in protic solvents such as ethanol and water. The highest yield (100 %) was observed in water at 50 °C using H2O solvent. Additionally, the nanohybrid exhibited significant potential for “green” click chemistry by efficiently synthesizing 1,2,3-triazoles under mild conditions, with low catalyst loading. Its magnetic properties facilitated easy recovery, and the catalyst maintained high activity over six cycles, making it suitable for sustainable applications in organic transformations.

Highly active iron oxide@NC catalyst derived from the iron acetate/polyacrylonitrile threads: Driving nitroarene conversion to value‐added amines

AbstractChemoselective reduction of nitroarenes to corresponding arylamines is a significant reaction in the chemical industry. However, in the presence of other reducible groups, including halogenated nitrobenzene, nitrobiphenyl, and nitroquinoline in the same molecule of nitroaromatics, the control of chemoselectivity remains challenging. Here, a facile fabrication of a heterogeneous iron‐based catalyst is reported as a potential alternative to precious metal catalysts for the chemoselective reduction of nitroarenes. The pyrolysis of iron acetate/polyacrylonitrile (PAN) template under an inert atmosphere furnishes active Fe3O4 nanoparticles (NPs) encapsulated in nitrogen‐doped (N‐doped) carbon layers, which can provide more catalytic active sites (Fe3O4/PAN@800). Notably, non‐precious iron oxide NPs supported on N‐doped carbon support prevent aggregation, thereby enhancing the catalytic activity. The sustainable and reusable Fe3O4/PAN@800 catalyst, having only 0.8% metal content as demonstrated by x‐ray photoelectron spectroscopy, delivers excellent yields of corresponding amines from differently functionalized nitroarenes. Hydrogenation of a series of structurally functionalized nitroarenes produced excellent yields of anilines, which serve as building blocks and intermediates for fine and bulk chemicals. Hydrogenation of 2‐chloro‐3‐nitropyridine, 2‐nitro‐1,1′‐biphenyl, ortho‐nitroaniline, and 4‐aminophenyl acrylonitrile yielded respective anilines up to 99%. The active sites of Fe3O4 have magnetic performance, hence, the catalyst can be easily recovered using a magnet and reused for at least five cycles without significant loss of catalytic activity. Therefore, the easily prepared, cost‐effective, and reusable Fe3O4/PAN@800 catalyst presented in this study shows potential for applications in the selective reduction of aromatic nitro compounds. Consequently, this study potentially establishes a guideline for the facile preparation of abundant transition‐non‐noble metal‐based reusable supported catalysts for various applications in the chemical industry.

Exploring Multifaceted Roles of Nitroreductases in Bacterial, Animal and Plant Biosystems and their Detection using Fluorescent Probes

AbstractNitroreductases are the enzymes that can convert nitroaromatic substances including explosives like TNT to their corresponding nitrite, hydroxylamine or amino derivatives with reduced NADH or NADPH as an electron donor. A wide range of nitroreductases are known to present in bacterial genomes that are explored for their potential in the reduction of nitroaromatic compounds and they are used in converting prodrugs to toxic hydroxylamine derivatives causing tumor cell killing. Likewise, in cancer cells, the low oxygen condition called hypoxia is a characteristic of solid tumors and during hypoxia nitroreductase gene expression occurs. Moreover, due to the ability of nitroreductases to reduce nitroaromatic compounds, phytoremediation potential of plants was inspected by expressing bacterial nitroreductase genes in plants through genetic engineering. Due to its diversity and widespread applications in different biosystems, its detection has gained momentum among the scientific community. Designing fluorescent probes for detecting nitroreductases has emerged as a beneficial tool compared to conventional monitoring approaches due to their high sensitivity, selectivity, and real‐time monitoring ability. This review aims to provide an understanding of the activity and the status of nitroreductases in bacteria, plants and animal cells as well as the significance of fluorescent imaging‐related studies by employing recently designed probes.

Rapid metal-free reduction of aromatic nitro compounds to aromatic amines in MeOH/H2O with B2pin2

The efficient reduction of nitro compounds to their corresponding amino compounds has been a challenging task. In this study, we developed a method for the rapid reduction of aromatic nitro compounds to aromatic amines. The method uses B2pin2 as the reducing agent and NaOH as the base, and the reaction can be completed in 15 min at 50 °C. A range of nitro compounds containing a variety of sensitive functional groups, such as halogen, thioether, cyano, vinyl, and heteroaryl were chemoselectively reduced to the corresponding anilines in good yields.

Phytosynthesis of CeO2-ZnO Nanocomposites Mediated by Parkia Speciosa Hassk Bark Aqueous Extract as Superior Photocatalyst in Reduction of Nitroaromatic Compound

Phytosynthesis of CeO2-ZnO Nanocomposites Mediated by Parkia Speciosa Hassk Bark Aqueous Extract as Superior Photocatalyst in Reduction of Nitroaromatic Compound

Encapsulated Dye in Coordination-Assembled Octahedron for Visible-Light-Driven Proton Reduction and Nitroaromatic Hydrogenation.

To mimic the finely tuned natural photosynthetic systems, a large metal-organic octahedron was synthesized by one-pot self-assembly with modified triphenylamine ligands and redox-active cobalt ions. By encapsulating an organic dye, fluorescein (Fl), within the inner cavity of the octahedron, the host-guest supramolecular system was provided for light-driven hydrogen production. The intimate distance between the redox site and the photosensitizer in the supramolecular metal-organic cage allowed the photoinduced electrons to transfer from the excited state Fl* to the redox cobalt center in a pseudo-intramolecular pathway. The supramolecular system showed good performance in light-driven hydrogen production and the reduction of nitroaromatic compounds. Control experiments based on a mononuclear compound resembling a cobalt corner of the octahedron and inhibitor competition provided evidence of enzyme-like catalytic behavior. The supramolecular reaction pathways within confined spaces contribute to the superior activity of the host-guest system.

Green Synthesis of Carbon Quantum Dots and Carbon Quantum Dot-Gold Nanoparticles for Applications in Bacterial Imaging and Catalytic Reduction of Aromatic Nitro Compounds

Green Synthesis of Carbon Quantum Dots and Carbon Quantum Dot-Gold Nanoparticles for Applications in Bacterial Imaging and Catalytic Reduction of Aromatic Nitro Compounds

Copper oxides supported sulfur-doped porous carbon material as a remarkable catalyst for reduction of aromatic nitro compounds

Synthesis and manufacturing of metal–organic framework derived carbon/metal oxide nanomaterials with an advisable porous structure and composition are essential as catalysts in various organic transformation processes for the preparation of environmentally friendly catalysts. In this work, we report a scalable synthesis of sulfur-doped porous carbon-containing copper oxide nanoparticles (marked CuxO@CS-400) via direct pyrolysis of a mixture of metal–organic framework precursor called HKUST-1 and diphenyl disulfide for aromatic nitro compounds reduction. X-ray diffraction, surface area analysis (BET), X-ray energy diffraction (EDX) spectroscopy, thermal gravimetric analysis, elemental mapping, infrared spectroscopy (FT-IR), transmission electron microscope, and scanning electron microscope (FE-SEM) analysis were accomplished to acknowledge and investigate the effect of S and CuxO as active sites in heterogeneous catalyst to perform the reduction-nitro aromatic compounds reaction in the presence of CuxO@CS-400 as an effective heterogeneous catalyst. The studies showed that doping sulfur in the resulting carbon/metal oxide substrate increased the catalytic activity compared to the material without sulfur doping.

Catalytic Reduction of Aromatic Nitro Compounds in Aqueous Media using Silver Nanoparticles Embedded-Preyssler Functionalized Cellulose Biocomposite as a Green and Recoverable Catalyst

Reduction reactions of aromatic nitro compounds to amines with high conversion and chemoselectivity have been achieved using a combination of catalytic quantities of silver nanoparticles embedded Preyssler-cellulose biocomposite (PC/AgNPs) with NaBH4 under mild conditions and in an aqueous medium. The stabilization of silver nanoparticles on the surface of the Preyssler-functionalized cellulose biocomposite with more accessible active sites may be reliable for increased catalytic hydrogenation.

Harnessing the Oxygen Vacancies in Metal Oxides for Nitroreduction

AbstractOxygen vacancies are one of the prominent types of defects in metal oxides. In addition to their role in modifying the electronic properties in solids, these sites have been shown to activate chemical bonds. As a result, the use of defect‐rich metal oxides in the organic transformations is promising. The article gives an overview of various chemical processes that are in use for the chemical reduction of aromatic nitro compounds to amines. Recently, application of oxygen vacancies in transition metal oxide for the selective reduction of aromatic nitro compounds to the corresponding amines has emerged as a new method of synthesis of amines. Oxygen vacancies in reducible oxide such as CuO have been shown to decompose hydrazine hydrate to H2 and in situ cause the reduction of nitro arenes to corresponding amines. This concept article discusses the literature pertaining to the synthesis of nitro reduction reaction, various strategies employed thus far and the place the defect‐mediated synthesis holds. The article also discusses the perspectives and challenges that remain to be addressed to gain more insights into the mechanistic understanding of the role of oxygen vacancies in nitro reduction and beyond.

Graphene quantum dots incorporated ZIF‐67 for stabilization of Au nanoparticles: Efficient catalyst for A3‐coupling and nitroarenes reduction reactions

Zeolitic imidazolate framework‐67 (ZIF‐67) functionalized with graphene quantum dots was prepared and utilized for the reduction of Au (III) and stabilization of Au nanoparticles. This newly prepared ZIF‐67/GQD@Au was characterized with different techniques and employed as a capable heterogeneous catalyst for reduction of aromatic nitro compounds and A1‐coupling reaction of alkynes, amines, and aldehydes in water solvent. Experiments indicate that this catalyst is able to reduce nitroarenes in short reaction times (10–20 min) in water at room temperature and corresponding amines were obtained in excellent yields (90–100%). Also, reactions of structurally different alkynes, amines, and aldehydes in the presence of this catalyst proceed effectively at 60°C and desired propargylic amine achieved in good to very good yields (76–88%) in water during 1 day. This catalyst displayed excellent stability and recyclability in both reactions and recycled for six runs with a small decrease in the activity.

A New Catalytic Performance of Mn2O3 Nanorods for Reduction of Aromatic Nitro Compounds

The reduction of aromatic nitro compounds is the simplest and most widely used method for preparing aniline compounds, and widely used in chemistry, biology, medicine, dyes, and so on. Among them, reduction of aromatic nitro compounds by sodium borohydride usually requires noble metal-based catalyst, which results in difficulty in industrial application. In this letter, we report a discovery that the Mn2O3 nanorods can replace noble metal nanoparticles to efficiently catalyze the reduction of aromatic nitro compounds with different types of substituents by NaBH4, and moderate to excellent yields were obtained. By studying the similar catalytic performance of different manganese oxide materials, we proposed a plausible catalytic mechanism. Our discovery will open up new applications of manganese oxide materials in the field of catalysis.

OBTENÇÃO DE AMINAS PRIMÁRIAS A PARTIR DA REDUÇÃO DE NITROCOMPOSTOS AROMÁTICOS VIA PROTOCOLOS DE REAÇÕES SUSTENTÁVEIS PARTE II: EM MEIO ORGÂNICO

SYNTHESIS OF PRIMARY AMINES FROM THE REDUCTION OF AROMATIC NITRO COMPOUNDS THROUGH SUSTAINABLE REACTION PROTOCOLS PART II: REACTIONS IN ORGANIC MEDIA. The reduction of nitroarenes is the main methodology to produce anilines, important precursors of building blocks, dyes, and drugs. Continuing our goal of describing sustainable methodologies for the reduction of nitroarenes to their respective anilines, herein we compile selected reaction protocols, using organic medium, reported from 2017 to 2023, in order to provide a comprehensive and complementary view of the new processes and catalysts developed during this period.

Chemoselective reduction of aromatic nitro compounds (o-nitrophenol derivatives) using simple borane-THF without transition metal catalysts, additives, or ligands

Chemoselective reduction of aromatic nitro compounds (ortho-nitrophenol derivatives) using Borane in THF (BH3-THF) at room temperature, without using an additional metal catalyst is reported. Interestingly, nitroarenes containing two or three groups, a selective reduction of the nitro group adjacent to the hydroxy group is observed which happens to be the first Chemoselective reduction protocol for nitro groups using BH3-THF. The presence of the phenolic hydroxyl group is found to be the key that aids in hydrogen transfer to the nitro group through a cyclic transition step.

A novel synthesis of β-CD@SA@Ag composite hydrogel microspheres with high catalytic activity and environmental adaptability

The composite of hydrogels and noble metal nanoparticles has wide applications in the field of functional materials. In this paper, we developed a novel and green strategy to synthesize a kind of composite hydrogel microspheres containing silver nanoparticles and β-cyclodextrin (β-CD) modified sodium alginate (β-CD@SA@Ag) without use of strong reducing reagent. First, β-CD was chemical linked to SA by epichlorohydrin (ECH) to form the β-CD modified polymer (β-CD@SA). then AgNO3 was added to the as-prepared polymer solution, in which silver nanoparticles were formed by the reducing power of β-CD units. Subsequently, by reversed-phase emulsion method and ionic cross-linking, a kind of β-CD@SA@Ag hydrogel microspheres were obtained. The structure and morphology of the composite material were characterized in detail by Fourier infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Test data indicated that silver nanoparticles evenly dispersed in the composite material. On the basis, the adsorption and catalytic performances of the β-CD@SA@Ag hydrogel microspheres were studied towards to the reduction of aromatic nitro compounds. Research results showed that the β-CD@SA@Ag hydrogel microspheres had excellent catalytic activity along with high environmental adaptability. whether in pure water, tap water or river water, aromatic nitro compounds can be completely reduced within 2–13 min. Moreover, the morphology of microspheres of the composite material endows the composite material with high stability and reusability. We believe that our work would provide a new idea for the green synthesis of organic-inorganic composite functional materials.

Enhancement of Bifunctional Catalytic Performance of G‐C3N4@ Ag Composite by NaBH4 Etching

AbstractHerein, a novel composite of g‐C3N4 and silver nanoparticles(g‐C3N4@Ag) with enhanced bifunctional catalytic activity through chemical etching is reported. A kind of g‐C3N4@Ag composite by one‐pot route, then treated the product with sodium borohydride (NaBH4) solution for a certain time is first synthesized. The property and morphology of the g‐C3N4@Ag composite changed greatly after the treatment. Compared with the pristine g‐C3N4@Ag composite, the NaBH4‐etching endowed g‐C3N4@Ag composite (RACN) with smoother two‐dimensional plane structure, as well as an extension of the conjugate system which originating from the stronger chemical connection between the Ag nanoparticles and g‐C3N4. Furthermore, research results indicated that the RACN showed superior broad‐spectrum catalytic performance for the reduction of aromatic nitro compounds, and the catalytic efficiency of the RACN is enhanced dozens of times by the treatment. Moreover, the photocatalytic activity of the RACN is also greatly improved. This discovery provides an efficient and facile method toward the enhancement of catalytic activity of semiconductor and metal nanoparticle composites by chemical etching.

Surfactant-free synthesis of Ag@TiO2 and CuO@TiO2 photocatalyst: a comparative study of their photocatalytic activity for reduction of nitroaromatics in water

The reduction of harmful nitroaromatics to useful amino-aromatics have significant opportunities in synthetic chemistry. Here a visible-light-driven eco-friendly method for the selective reduction of aromatic nitro compounds to their corresponding amines in aqueous solution by using Ag@TiO2 and CuO@TiO2 is described. It was observed that both Ag@TiO2 and CuO@TiO2 are photo-catalytically more efficient compared to bare TiO2 and CuO@TiO2 has higher activity over Ag@TiO2 for the said conversion. The structural and morphological characterization of the as-synthesized catalysts has been done with SEM-EDX, TEM, powder XRD, ICP-AES, XPS, Photoluminescence, and UV-vis spectroscopic techniques. The nanocomposites Ag@TiO2 and CuO@TiO2 exhibit pure anatase phase with average crystallite size of 5.89 nm and 5.87 nm respectively as calculated from the Debye-Scherrer equation depending on the (101) plane. UV-visible results inferred enhanced optical properties of both the synthesized catalysts and revealed a reduced band gap (3.07 eV for Ag@ TiO2 and 2.5 eV for CuO@ TiO2) as compared to neat TiO2 (3.36 eV). Various nitro compounds were tolerated under 150 W LED as a light source (13.9 lumens for an area of 0.2 ft2) in an aqueous medium at room temperature (30 °C) using NaBH4 as a reducing agent to access corresponding amines in satisfying yields (78%–99%). The catalyst can be separated from the reaction mixture by simple centrifugal precipitation and reused for up to six consecutive cycles without apparent loss of its catalytic activity. The products were characterized by 1H-NMR spectroscopic techniques and compared with authentic samples.

Realizing the Continuous Chemoenzymatic Synthesis of Anilines Using an Immobilized Nitroreductase.

The use of biocatalysis for classically synthetic transformations has seen an increase in recent years, driven by the sustainability credentials bio-based approaches can offer the chemical industry. Despite this, the biocatalytic reduction of aromatic nitro compounds using nitroreductase biocatalysts has not received significant attention in the context of synthetic chemistry. Herein, a nitroreductase (NR-55) is demonstrated to complete aromatic nitro reduction in a continuous packed-bed reactor for the first time. Immobilization on an amino-functionalized resin with a glucose dehydrogenase (GDH-101) permits extended reuse of the immobilized system, all operating at room temperature and pressure in aqueous buffer. By transferring into flow, a continuous extraction module is incorporated, allowing the reaction and workup to be continuously undertaken in a single operation. This is extended to showcase a closed-loop aqueous phase, permitting reuse of the contained cofactors, with a productivity of >10 gproduct gNR-55-1 and milligram isolated yields >50% for the product anilines. This facile method removes the need for high-pressure hydrogen gas and precious-metal catalysts and proceeds with high chemoselectivity in the presence of hydrogenation-labile halides. Application of this continuous biocatalytic methodology to panels of aryl nitro compounds could offer a sustainable approach to its energy and resource-intensive precious-metal-catalyzed counterpart.

Reduced graphene Oxide/NiO based nano-composites for the efficient removal of alizarin dye, indigo dye and reduction of nitro aromatic compounds

Removal of alizarin red S (ARS) and Indigo dye from aqueous media and reduction of nitro aromatic compounds are successfully done under mild condition by using reduced Graphene Oxide-Nickel Oxide (rGO-NiO) nanocomposite as catalyst. RGO-NiO is well characterized by different analytical techniques. Morphology, structural, and composition studies done by HRTEM, FESEM, EDX, TGA, FTIR, XPS, Raman spectroscopy, and XRD. RGO-NiO nanocomposite has high stability for the removal of ARS, Indigo dye, reduction reaction nitro aromatic compounds.