Reduction Of Aromatic Nitro Compounds Research Articles

Catalytically active (Pd) nanoparticles supported by electrospun PIM-1: Influence of the sorption capacity of the polymer tested in the reduction of some aromatic nitro compounds

Microfibers of the first so-called polymer of intrinsic microporosity (PIM-1) were prepared by electrospinning 10 wt.% PIM-1 in tetrachloroethane and used as immobilized supports for catalytic reactions. Solutions with varied concentrations of palladium diacetate (PdAc2) were coated on electrospun PIM-1 to show that PIM-1 is a superior catalyst supporting material with a high surface per weight ratio. Palladium (Pd) nanoparticles (NPs) were produced via the reduction of the PdAc2 with ethanol followed by subsequent thermal treatment for durably fixing the NPs on the fibers. A comparison of the catalytic activity of PIM-1 supported PdNPs was made with that of similarly produced electrospun nanofibers of polyacrylonitrile (PAN) and polyimide (6FDA-6FpDA) with catalytic PdNPs.The morphology of the electrospun fibers and the distribution of the Pd nanoparticles on the outer surface of the fibers were determined by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) analysis of the cross section of the fibers showed the distribution of PdNPs across the fiber with a slight excess on the outer surface of the fibers. The nanoparticles (NPs) supported by the electrospun polymers catalyzed the reduction of different aromatic nitro compounds to their corresponding amino derivatives. The kinetics of the reduction reactions were monitored by ultraviolet-visible (UV-Vis) spectroscopy. Results showed that the PdNPs supported by electrospun PIM-1 fiber possessed high activity in the reduction reaction with an only slight dependence on the fiber diameter in the case of p-nitrophenol, while in the case of the dinitro compounds the dependence of the kinetics on the fiber diameter was more pronounced. The catalytic tests on two dinitro compounds proved the higher sorption of PIM-1 for p-nitrophenol is responsible for the higher catalytic activity of PIM-1 based catalytic nanofiber mats. These results clearly show that the catalytic activity of the PIM-1 fiber mats is higher compared to the fiber mats from PAN or 6FDA-6FpDA in the case of small reactants, which is mainly due to the fact that the PdNPs are also formed within the microporous PIM-1 fibers, while this is not the case for the other more dense fibers, where the catalytic particles are located only on the outer surface.

Photosynthesis of silver nanoparticles using Durio zibethinus aqueous extract and its application in catalytic reduction of nitroaromatics, degradation of hazardous dyes and selective colorimetric sensing of mercury ions

A simple green route was reported to prepare highly stable silver nanoparticles. The aqueous leaf extract of Durio zibethinus reduces Ag+ to Ag0 in the presence of natural sunlight. The capping and stabilization of dAgNPs by the phytoconstituents of Durio zibethinus was confirmed by FTIR. TEM confirms that the dAgNPs are spherical in shape with a size range between 10–25 nm. XRD pattern confirmed that the dAgNPs are arranged in the face-centred cubic structure. The catalytic activity of the dAgNPs was proved by sodium borohydride mediated reduction of nitro aromatic compounds and degradation hazardous organic dyes. The reaction kinetics was analysed by pseudo-first order equation. Regardless of the efficacy of degrading organic dyes, we showed by zebrafish mortality assay that the toxicity of the dye degraded water reduced drastically. Besides catalysis, the dAgNPs has the potential to selective colorimetric sensing of hazardous mercury ion in aqueous solution.

Catalytic reduction of aromatic nitro compounds: general questions, equipment, enlarged laboratory tests

The article is devoted to issues of amines production from nitro compounds. The processes of catalytic reduction of aromatic nitrocompounds by hydrogen to amines have practically superseded all other methods for the production of aromatic amines in large-tonnage plants. Aromatic mono-, di- and polyamines, due to their high reactivity, are widely used in the production of various compounds (photochemicals, fuel stabilizers and additives lubricating oils, in the paint and varnish industry, for painting natural and synthetic fibers). Authors compare methods of nitro compounds reduction and show different variants of apparature design. The article also describes the results of enlarged laboratory examinations of the deposited catalysts synthesized by authors in reactions of p-phenylenediamine, p-amino-diethylaniline, o- and p-aminophenols production. By using relatively small amounts of catalysts (0.48-0.6 g of catalyst by hydrogenating 50 g of an aromatic nitro compound) were obtained high amine yields of 90-98.7%.

Simple and Practical Synthesis of Various New Nickel Boride-Based Nanocomposites and their Applications for the Green and Expeditious Reduction of Nitroarenes to Arylamines under Wet-Solvent-Free Mechanochemical Grinding

In this paper, we report a simple synthesis of four new nickel boride-based nanocomposites, namely Ni2B@ZrCl4, Ni2B@Cu2O, Ni2B@CuCl2 and Ni2B@FeCl3, from commercially available and cheap starting materials. All of the new Ni2B-based nanocomposites were well characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Further, the catalytic applications of these new nanocomposites were successfully evaluated in the wet-solvent-free reduction of aromatic nitro compounds to arylamines with sodium borohydride (NaBH4) at room temperature by a mechanochemical grinding technique. All the introduced catalytic systems provide excellent yields of arylamines in very short reaction times for a wide range of substrates. Also, recoverability and reusability of the new nanocomposites were investigated.

Novel Au Nanoparticles-Strewn MnOOH Nanorod Composites: Simple Fabrication and Application in the Catalytic Reduction of Aromatic Nitro Compounds

In this study, a surface functionalization process was designed for the preparation of Au nanoparticles-strewn MnOOH nanorods with enhanced catalytic performance for reduction of aromatic nitro compounds. (3-Aminopropyl) triethoxysilane was used as a modifier to link MnOOH nanorods and Au nanoparticles. The as-obtained nanocomposite was characterized by powder X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy (TEM/HRTEM), selected area electron diffraction, energy dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Our results showed that the MnOOH/Au nanocomposite can be used as a highly efficient catalyst for the reduction of aromatic nitro compounds in the presence of NaBH4 solution.

Green synthesis & catalytic study of sucrose stabilized Pd nanoparticles in reduction of nitro compounds to useful amines

An efficient chemoselective reduction of aromatic nitro compounds to corresponding amino analogues was achieved using palladium/sucrose (Pd/S) nanoparticles as an eco friendly catalyst, a green approach formate in ethanol at RT. The reductions are fruitfully carried out in presence of various other reducible functional groups such as halo, alkoxy, carbonyl, and cyanide etc. The reactions are worthy and high yielding (100%).

Electrocatalytic reduction of nitroaromatic compounds by activated graphite sheets in the presence of atmospheric oxygen molecules

Abstract The anthropogenic climate and environmental issues incite the remediation of nitroaromatic compounds (NACs). Therefore, most of the researches have been devoted to the electrocatalytic reduction of NACs. Mainly, the carbonaceous materials have been employed as an electrode material for the determination of NACs. However, the effect of oxygen reduction is necessary to address with the electrocatalytic reduction of NACs. Hence, this work mainly focuses the reduction of NACs with the saturated oxygen and atmospheric oxygen conditions. The graphite and nitrobenzene (NB) were chosen as a model electrode and analyte for assess the effect of oxygen reduction. Though, the graphite is no longer express high electrocatalytic activity thus the activated graphite sheets were employed in the determination of NACs. Interestingly, the activated graphite sheets exhibited an excellent performance to the reduction of nitrobenzene and revealed an acceptable linear range around 0.05–1100 µM, 0.05–147 µM and 0.05–145 µM, in the N2, O2 and aerated atmospheres, respectively. Moreover, the lowest detection limits were obtained around 0.026 µM, 0.031 µM and 0.032 µM, for the N2, O2 and aerated atmospheres respectively. In order to investigate the electrochemical reactivity of activated graphite, four different NACs were selected such as flutamide (anti-cancer drug), methyl parathion (pesticide), 4-nitro aniline and 4-nitro phenol.

Dendrimer encapsulated Silver nanoparticles as novel catalysts for reduction of aromatic nitro compounds

Polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where dendrimer acts as reducing and stabilizing agent. The encapsulated AgNPs were well characterized using TEM, DLS and XPS techniques. The synthesized AgNPs showed excellent catalytic activity towards the reduction of aromatic nitro compounds with sodium borohydride as reducing agent and the results substantiate that dendrimer encapsulated AgNPs can be an effective catalyst for the substituted nitro aromatic reduction reactions. Also the kinetics of different nitro compounds reductions was studied and presented.

An Efficient Method for Reduction of Nitroaromatic Compounds to the Corresponding Aromatic Amines with NH2NH2·H2O Catalysed by H2O2-Treated Activated Carbon

An efficient and green protocol for the reduction of nitroaromatic compounds to the corresponding amines has been developed. The reduction catalyst system includes NH2NH2·H2O and H2O2-treated activated carbon. Without adding additional metals, the H2O2-treated activated carbon could be reused for many cycles without decreasing catalytic efficiency. The aromatic amines could be obtained in good to excellent yields.

Nitro group reduction and Suzuki reaction catalysed by palladium supported on magnetic nanoparticles modified with carbon quantum dots generated from glycerol and urea

Glycerol and urea were used as green and cheap sources of carbon quantum dots (CQD) for modifying Fe3O4 nanoparticles (NPs). The obtained CQD@Fe3O4 NPs were used for the stabilization of palladium species and the prepared catalyst, Pd@CQD@Fe3O4, was characterized using various techniques. This magnetic supported palladium was applied as an efficient catalyst for the reduction of aromatic nitro compounds to primary amines at room temperature using very low palladium loading (0.008 mol%) and also for the Suzuki–Miyaura cross‐coupling reaction of aryl halides as well as challenging heteroaryl bromides and aryl diazonium salts with arylboronic acids and with potassium phenyltrifluoroborate. This magnetically recyclable catalyst was recovered and reused for seven consecutive runs in the reduction of 4‐nitrotoluene to p‐toluidine and for ten consecutive runs in the reaction of 4‐iodoanisole with phenylboronic acid with small decrease of activity. The catalyst reused in the Suzuki reaction was characterized using transmission electron microscopy, vibrating sample magnetometry and X‐ray photoelectron spectroscopy. Using experiments such as hot filtration and poisoning tests, it has been shown that the true catalyst works under homogeneous conditions according to the release–return pathway of active palladium species.

Catalytic Reduction of Nitroarenes by Dipalladium Complexes: Synergistic Effect

The direct reaction between 2,7-bis(2-pyridinyl)-1,8-naphthyridine (bpnp) and Pd(CH3COO)2 in CF3COOH yields the new dinuclear palladium(II) complex [Pd2(bpnp)(μ-OH)(CF3CO2)2](CF3CO2) (1). Similarly, substitution of Pd(CH3CN)4(BF4)2 with bpnp in DMF gives [Pd2(bpnp)(μ-OH)(DMF)2](BF4)3 (2). Treatment of 1 or 2 with Cl– readily provide the chloro-substituted species [Pd(bpnp)(μ-OH)(Cl)2]+. All complexes were characterized by spectroscopic methods, and the structure of 2 was further confirmed by X-ray crystallography. Complex 1 is an efficient catalyst for the reduction of aromatic nitro compounds leading to the corresponding aniline derivatives under atmospheric pressure of hydrogen at 50 °C. The mechanistic pathway of the catalysis is investigated. From the reaction pathway, it is suggested that a facile condensation of nitroso and hydroxylamine intermediates is enabled by the dipalladium system and the desired transformation proceeds smoothly under mild reaction conditions to yield the reduced product.

Well-dispersed rhenium nanoparticles on three-dimensional carbon nanostructures: Efficient catalysts for the reduction of aromatic nitro compounds

Rhenium nanoparticles (ReNPs) supported on ordered mesoporous carbon (OMC) as a catalyst (Re/OMC) through a solvent-evaporation induced self-assembly (ELSA) method were prepared. The synthesized heterogonous catalyst was fully characterized using X-ray diffraction, field emission transmission electron microscopy, N2 sorption, metal dispersion, thermogravimetric analysis, Raman, Fourier-transform infrared, and X-ray photon spectroscopies. In addition, the catalyst was applied to reduce the aromatic nitro compounds (ANCs) for the first time in aqueous media and the reactions were monitored by following the intensity changes in the UV–vis absorption spectra with respect to time. This method provides the advantages of obtaining a high rate constant (k), green reaction conditions, simple methodology, easy separation and easy workup procedures. Moreover, the catalyst can be easily recovered by centrifugation, recycled several times and reused without any loss of activity. The higher activity of this catalyst was attributed to higher dispersion and smaller particle size of ReNPs as observed from FE-TEM and XRD results.

常温常圧下での Pd・C 触媒による芳香族ニトロ化合物の接触水素還元 : 反応水素ガスの体積を測定する

常温常圧下での Pd・C 触媒による芳香族ニトロ化合物の接触水素還元 : 反応水素ガスの体積を測定する

Copper Nanoparticles Encapsulated Alginate Composite for Reduction of Aromatic Nitro Compounds

Copper Nanoparticles Encapsulated Alginate Composite for Reduction of Aromatic Nitro Compounds

Comparative assessment of azo dyes and nitroaromatic compounds reduction using indigenous dye-decolorizing bacteria

Abstract As known, azo dyes and nitro aromatic compounds were popularly used in industry and biotreatment of these chemicals were the most environmentally friendly. As literature indicated, azoreductases and nitroreductases were possibly originated from identical reductases. This study showed that excellent dye decolorizers Aeromonas hydrophila NIU01 and Shewanella sp. WLP72 also revealed significant capabilities for reduction of nitroaromatic compounds. Moreover, supplementation of redox mediators—riboflavin and reduced nicotinamide adenine dinucleotide (NADH) apparently enhanced the efficiency of nitroreduction. This first-attempt study also disclosed that reduced metabolites of 2-nitrophenol (2-NP) also owned electron-shuttling characteristics. Augmentation of such reduced metabolites to azo dyes-bearing cultures could significantly improve the efficiency of reductive decolorization. To the best of our knowledge, there are no reports in literature revealing dye decolorization and nitroreduction characteristics of strains in Aeromonas and Shewanella genera. This first-attempt study was crucial to decipher synergistic interaction of enzymatic activities on reduction of dyes and nitroaromatics for bioremediation of multiple contaminants.

Magnetic Cube‐Shaped NiFe2O4 Nanoparticles: An Effective Model Catalyst for Nitro Compound Reduction

AbstractNoble‐metal nanocatalysts are quite popular, but the use of magnetic catalysts composed of ferrite materials is rare. Here, we have synthesized transition‐metal‐based cube‐shaped nanoparticles of approximately 11 nm in size, the so‐called magnetic nickel ferrite nanocatalyst (NFNC), by a new method and shown its use in the reduction of nitroaromatic compounds. The NFNC was characterized by using XRD, energy‐dispersive X‐ray spectroscopy, TEM, and field‐emission SEM to confirm the structural features and morphology of the particles. The catalytic activity of NFNC was investigated in the reduction of 4‐nitrophenol to 4‐aminophenol by monitoring the reaction by using UV/Vis spectroscopy. The catalytic activity, recyclability and reusability, rate constant of the reaction, and surface area were investigated in detail to understand the catalytic phenomenon. We measured up to 30 cycles of the catalytic reaction using our NFNC, which shows the high stability of the catalyst. BET analysis of the NFNC shows a surface area of 54.60 m2 g−1. Our NFNC has many advantages because it is prepared easily, cost effective, highly stable, and environmentally compatible. The magnetic properties of the NFNC help us to separate the particles easily after its use in the reduction without disturbing the final product.

Palladium nanoparticles supported on SiO2@Fe3O4@m-MnO2 mesoporous microspheres as a highly efficient and recyclable catalyst for hydrodechlorination of 2,4-dichlorophenol and reduction of nitroaromatic compounds and organic dyes

In this study, magnetic SiO2@Fe3O4@m-MnO2 microspheres with uniform morphology and mesoporous MnO2 shell were successfully prepared. The MnO2 sheets structured mesoporous shell could provide a large specific surface area, thereby increasing the catalytically active sites. Thus, magnetic SiO2@Fe3O4@m-MnO2 microspheres were used as a catalyst support. Palladium nanoparticles (Pd NPs) were successfully anchored with high dispersion on SiO2@Fe3O4@m-MnO2 surface, successfully obtained Pd(6%)/SiO2@Fe3O4@m-MnO2 nanocatalyst with a Pd weight percentage of 6%. The obtained nanocatalyst was employed in the hydrodechlorination of highly toxic 2,4-dichlorophenol and catalytic reduction of the widely used nitroaromatics and organic dyes under ambient conditions. In these catalytic reactions, the Pd(6%)/SiO2@Fe3O4@m-MnO2 nanocatalyst with large and accessible pore surface area exhibited excellent catalytic activity as compared to other noble metal supported catalysts. The Pd(6%)/SiO2@Fe3O4@m-MnO2 nanocatalyst could also be easily and conveniently recovered from the reaction mixture by using an external magnet, attributed to its magnetism, thus preventing the catalyst loss. Moreover, it could also be reused for at least six times without significant decrease in the catalytic activity, indicating its excellent reusability and stability. This study provides a useful platform and a new perspective for fabricating mesoporous MnO2 microspheres based noble metals modified catalysts for environmental catalysis.

Vortex-layer devices as import-substituting equipment to produce paints and adhesives

It is proposed to use domestically produced vortex layer devices instead of imported bead mills for grinding pigments (and the synthesis of some of them) in the paint industry, for preparation of intermediates of film formers for the reduction of aromatic nitro-compounds to primary amines used as curing agents for epoxy oligomers, in the synthesis of dyes, etc. It is shown that using these devices results in not only technological advantages over bead mills, but will also allow us to replace some types of imported raw materials.

Tuning the reduction power of visible-light photocatalysts of gold nanoparticles for selective reduction of nitroaromatics to azoxy-compounds—Tailoring the catalyst support

It is a challenge to attain high selectivity to azoxy-compounds in the reduction of aromatic nitro compounds as azoxy-compounds can be readily reduced to azo- and aniline compounds. We proposed a new solution to this challenge: gold nanoparticles (AuNPs) on hydrotalcite (HT) support were used to catalyze the reduction under visible light irradiation at ambient temperature; and phosphate (PO43−) and metal (such as Ga3+, Fe3+, Zn2+) ions were incorporated into the HT support to moderate the reduction power of the catalyst avoiding the formation of azo- and aniline compounds. Very high azoxy-compound selectivity was achieved under green mild conditions. The photocatalytic activity strongly depends on the incident light wavelength and intensity, and we can further enhance the catalytic efficiency of this photocatalytic process by slight increase in reaction temperature (e.g. 10–20°C). Moreover, high stability and recyclability of the catalyst were also observed under the investigated conditions. A plausible reaction mechanism was proposed based on the experimental results and literatures. The introduction of both phosphate and metal ions into HT support can prevent the further reduction of azoxy-compounds to azo-compounds or anilines and achieve excellent selectivity to azoxy-compounds. This study reveals that we may engineer a product chemoselectivity by tailoring the supporting materials, and may present a new strategy towards the development of versatile heterogeneous photocatalysts.

Chitosan-based film supported copper nanoparticles: A potential and reusable catalyst for the reduction of aromatic nitro compounds

In this study, copper nanoparticles (CuNPs) were synthesized and stabilized into a chitosan/poly(vinyl alcohol) (CP) based film using a simple protocol under mild conditions. The polymeric matrix utilized in this study allows synthesizing stable nanoparticle with narrow size distribution within the film matrix. Further, this system showed very attractive properties, such as good mechanical properties, chemical resistance, easy handling during use and recovery, relatively low-cost as compared to other similar systems, among others. The catalytic performance of CP-Cu film was tested in the reduction reaction of nitrobenzene (NB) to aniline (AN). Our findings reveal that CP-Cu film catalyzes the reaction efficiently and also decreases the energy of activation (Ea) as compared to other catalysts. The catalytic efficiency of CP-Cu regarding this reaction was kept even after 6 consecutive reuse cycles. All these results rank this novel system as a promising catalyst in the reduction of aromatic nitro compounds to aromatic amines.