Polymer supported Nickel nanoparticles as recyclable catalyst for the reduction of nitroarenes to anilines in aqueous medium (original) (raw)
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Journal of Chemical Sciences, 2018
A novel resin-encapsulated nickel nanocatalyst has been synthesized by a modified impregnation method using nickel acetate tetrahydrate in presence of sodium borohydride as a mild reducing agent. The synthesized nanocatalyst was characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The concentration of nickel nanoparticles encapsulated on resin was determined by inductively coupled plasma-mass spectroscopy (ICP-MS). Further, synthesized resinencapsulated nickel nanocatalyst was found to be stable and efficient in micromolar concentrations, for the selective reduction of functionalized nitroarenes to corresponding amines in good to high yield, under mild reaction conditions. The nanocatalyst shows excellent reusability.
Catalysts, 2018
We have demonstrated a convenient method of synthesizing nickel nanowires (NiNWs), which could be easily tuned to produce materials with a carefully defined nanostructure. By varying the concentration of the Ni precursor, pH of the medium or reaction temperature, we directly affected the diameter of the formed product as well as the yield of the process. The obtained material consisted of straight bundles of NiNWs, which revealed powerful catalytic action for the reduction of nitroarenes to appropriate amine derivatives. A selection of substrates were employed and all of them were successfully converted into the corresponding aromatic amine despite the presence of different substituents on the aromatic ring with high yields, even in large scale reactions. The results showed that NiNW-based catalysts could constitute efficient catalytic systems for the synthesis of aryl amines at industrial levels.
The catalytic reduction of nitroarenes under various catalytic systems has been widely reported in the flood of publications during last twenty years. This reaction has become a benchmark for testing catalytic activity of inorganic nanoparticles stabilized in various systems. This tutorial review presents design and classification of inorganic nanocatalysts along with their stabilizing agents used for catalytic reduction of nitroarenes. The techniques used for characterization of catalysts have been highlighted in this review. The mechanism of catalytic reduction has been described in a tutorial way. Factors affecting the rate of reduction of nitroarenes in the presence of metal nanoparticles stabilized in poly-electrolyte brushes, polyionic liquids, micelles, den-drimers, and microgels have been discussed for further development in this area.
Tetrahedron Letters, 2012
Anilines are one of the important chemical feedstocks and are utilized for the preparation of a variety of pharmaceuticals, agrochemicals, pigments, and dyes. In this context, the catalytic reduction of nitro functionality is an industrially vital process for the synthesis of aniline derivatives. Herein, we report an efficient nanosized bimetallic Pd−Au/TiO 2 nanomaterial which is proved to be quite efficient for rapid catalytic hydrogen transfer reduction of nitroarenes into corresponding amines. Significantly, the reduction process is successful under solvent-free and mild green atmospheric conditions. Bimetallic Pd−Au nanoparticles served as the active center, and TiO 2 played as a support in hydrogen transfer from the source hydrazine monohydrate. Typical results highlighted that the reactions were very rapid and the products were obtained in good to excellent yields. Significantly, the process was successful in the presence of a very low amount catalyst (0.1 mol %). Furthermore, the reaction showed good chemoselectivity and compatiblity with double or triple bond, aldehyde, ketone, and ester functionalities on the aromatic ring. Typical results indicated the true heterogeneous nature of the Pd−Au/TiO 2 nanocatalyst, where the catalyst retained the activity, without loss of its activity.
Hydrogenation of nitrobenzene over nickel nanoparticles stabilized by filamentous carbon
Applied Catalysis A-general, 2008
Simultaneous generation of filamentous carbon and nickel nanoparticles was achieved by decomposing methane over Raney-type skeletal nickel catalyst. Nickel nanoparticles were generated by metal disintegration and stabilized by filamentous carbon. This composite material was tested as a catalyst for the hydrogenation of nitrobenzene. The active phase of the catalysts consists of nickel nanoparticles in reduced form with superficial oxide layers. The catalysts exhibited excellent performance, producing clean aniline ($99% yield). ß
NiSb nanoparticles confined in SBA-15 are found to be highly efficient catalysts for nitroarene reduction reactions. The NiSb/SBA-15 catalysts with different chemical compositions were prepared using an adsorption–reduction method and were well characterized by XRD, N 2 sorption, UV-Vis, ICP-OES, SEM, TEM and EDAX. The effect of different metal concentrations of Ni and Sb on the formation of NiSb alloy nanoparticles on SBA-15 was investigated. The XRD, UV and TEM images confirmed the formation of uniform NiSb nanoparticles of size 4–6 nm on the SBA-15 support. The synthesized catalysts were screened for the nitroarene reduction using NaBH 4. The NiSb/SBA-15 catalyst showed excellent catalytic activity compared to NiSb nanoparticles of different particle sizes in p-nitrophenol reduction. The NiSb/ SBA-15 catalyst showed superior catalytic activity compared to any Ni nanoparticle catalysts reported so far. The NiSb/SBA-15 catalyst showed enhanced catalytic activity towards the reduction of various nitroarenes compared to Ni/SBA-15.
Reduction of Nitrobenzene to Aniline by CO/H2O in the Presence of Palladium Nanoparticles
Catalysts
The transformation of aromatic nitrocompounds into amines by CO/H2O is catalyzed by palladium(II) complexes. Recently, we have proposed that the catalytic cycle includes Pd0 as the transient intermediate and herein, for the first time, we describe the application of palladium nanoparticles (PdNPs) stabilized by monodentate N-heterocyclic ligands as nanocatalysts facilitating the reduction of Ar–NO2 into Ar–NH2 by CO/H2O. Among the series—Pd(II) complexes, PdNPs and commercial Pdblack—the highest catalytic activity was observed for PdNPs (3.0 ± 0.5 nm) stabilized by 4-Me-pyridine in the presence of 2-Cl-pyridine. The results may be helpful for mechanistic considerations on the role of metallic nanoparticles as active species in other organic processes.
Anilines are one of the important chemical feedstocks and are utilized for the preparation of a variety of pharmaceuticals, agrochemicals, pigments, and dyes. In this context, the catalytic reduction of nitro functionality is an industrially vital process for the synthesis of aniline derivatives. Herein, we report an efficient nanosized bimetallic Pd−Au/TiO 2 nanomaterial which is proved to be quite efficient for rapid catalytic hydrogen transfer reduction of nitroarenes into corresponding amines. Significantly, the reduction process is successful under solvent-free and mild green atmospheric conditions. Bimetallic Pd−Au nanoparticles served as the active center, and TiO 2 played as a support in hydrogen transfer from the source hydrazine monohydrate. Typical results highlighted that the reactions were very rapid and the products were obtained in good to excellent yields. Significantly, the process was successful in the presence of a very low amount catalyst (0.1 mol %). Furthermore, the reaction showed good chemo-selectivity and compatiblity with double or triple bond, aldehyde, ketone, and ester functionalities on the aromatic ring. Typical results indicated the true heterogeneous nature of the Pd−Au/TiO 2 nanocatalyst, where the catalyst retained the activity, without loss of its activity.
Molecules
In the present study, a novel heterogeneous catalyst was successfully fabricated through the decoration of palladium nanoparticles on the surface of designed Fe3O4-coffee waste composite (Pd-Fe3O4-CWH) for the catalytic reduction of nitroarenes. Various characterization techniques such as XRD, FE-SEM and EDS were used to establish its nano-sized chemical structure. It was determined that Pd-Fe3O4-CWH is a useful nanocatalyst, which can efficiently reduce various nitroarenes, including 4-nitrobenzoic acid (4-NBA), 4-nitroaniline (4-NA), 4-nitro-o-phenylenediamine (4-NPD), 2-nitroaniline (2-NA) and 3-nitroanisole (3-NAS), using NaBH4 in aqueous media and ambient conditions. Catalytic reactions were monitored with the help of high-performance liquid chromatography. Additionally, Pd-Fe3O4-CWH was proved to be a reusable catalyst by maintaining its catalytic activity through six successive runs. Moreover, the nanocatalyst displayed a superior catalytic performance compared to other catal...