Catalytic Reduction of Aromatic Nitro Compounds by Coinage Metal Nanoparticles

Pradhan, Narayan; Pal, and Anjali; Pal, Tarasankar

doi:10.1021/la000862d

Cited by 540 publications

(374 citation statements)

References 9 publications

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“…After normalization of k app by the molar concentration of silver in our suspensions (1.210 -5 M), we obtain a specific rate coefficient k = 122  16 s -1 M -1 , which is within the range of values observed for polymer-stabilized Ag nanoparticles (~25 nm) obtained at similar NaBH 4 concentrations [60], albeit much lower than values originally reported by Pradhan et al for bare Ag nanoparticles [55]. This suggests that, although we cannot exclude the presence of a partially blocking adsorbed layer, metallic surface sites at the carbon-supported Ag aggregates are highly available to catalyse heterogeneous reactions.…”

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositessupporting

confidence: 80%

“…The reduction rate of 4-nitrophenol is negligible in aqueous solutions of NaBH 4 , however, it is catalysed by the presence of noble metal nanoparticles [19,54,55]. Fig.…”

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositesmentioning

confidence: 97%

“…5a shows time-dependent UV-Vis spectra of Ag/CM aqueous suspensions containing 1.010 -2 NaBH 4 , after injection of 4-nitrophenol; spectra have been corrected by the scattering contribution in the microsphere suspension [56]. A maximum at 400 nm is characteristic of 4-nitrophenolate ions [54,55,57,58]; the peak decreased rapidly after injection into the Ag/CM : NaBH 4 suspension, indicating that the arylnitro group is consumed over time. The graph also shows the appearance of a peak at 290 nm, which is attributed to the formation of 4-aminophenol [54,55,57,58], thus confirming that the nitroaromatic compound is reduced to its corresponding arylamine.…”

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositesmentioning

confidence: 99%

“…A maximum at 400 nm is characteristic of 4-nitrophenolate ions [54,55,57,58]; the peak decreased rapidly after injection into the Ag/CM : NaBH 4 suspension, indicating that the arylnitro group is consumed over time. The graph also shows the appearance of a peak at 290 nm, which is attributed to the formation of 4-aminophenol [54,55,57,58], thus confirming that the nitroaromatic compound is reduced to its corresponding arylamine. Control experiments confirmed that no reduction takes place in the presence of NaBH 4 or carbon microspheres alone, but only when Ag/CM composite particles were used in suspension.…”

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositesmentioning

confidence: 99%

See 3 more Smart Citations

Natural reducing agents for electroless nanoparticle deposition: Mild synthesis of metal/carbon nanostructured microspheres

Duffy

Reynolds

Sanders

et al. 2013

Materials Chemistry and Physics

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Composite materials are of interest because they can potentially combine the properties of their respective components in a manner that is useful for specific applications. Here, we report on the use of coffee as a low-cost, green reductant for the room temperature formation of catalytically active, supported metal nanoparticles. Specifically, we have leveraged the reduction potential of coffee in order to grow Pd and Ag nanoparticles at the surface of porous carbon microspheres synthesized via ultraspray pyrolysis. The metal nanoparticle-on-carbon microsphere composites were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). To demonstrate the catalytic activity of Pd/C and Ag/C materials, Suzuki coupling reactions and nitroaromatic reduction reactions were employed, respectively.3

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Section: Reduction Of 4-nitrophenol Using Ag/cm Compositessupporting

confidence: 80%

“…The reduction rate of 4-nitrophenol is negligible in aqueous solutions of NaBH 4 , however, it is catalysed by the presence of noble metal nanoparticles [19,54,55]. Fig.…”

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositesmentioning

confidence: 97%

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositesmentioning

confidence: 99%

Section: Reduction Of 4-nitrophenol Using Ag/cm Compositesmentioning

confidence: 99%

See 2 more Smart Citations

Natural reducing agents for electroless nanoparticle deposition: Mild synthesis of metal/carbon nanostructured microspheres

Duffy

Reynolds

Sanders

et al. 2013

Materials Chemistry and Physics

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show abstract

“…The reduction of aromatic nitro groups using excess NaBH 4 in the presence of metal NPs as catalyst has been investigated. 2,[23][24][25] Very recently, shapeselective Au-Ag core-shell nanocrystals have been utilized for catalytic reduction of nitro compounds. 26 Apart from the catalysis reaction, metal NPs were also tested for surface enhanced Raman scattering (SERS) studies.…”

Section: Introductionmentioning

confidence: 99%

Enhanced catalytic and SERS activities of CTAB stabilized interconnected osmium nanoclusters

Ede

Nithiyanantham

Kundu

2014

Phys. Chem. Chem. Phys.

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A new route for the formation of osmium nanoparticles (NPs) having different morphologies like aggregated clusters, chain-like networks, and small spheres are reported. The synthesis was done by utilizing a simple wet-chemical method at room temperature (RT) by the reaction of OsO 4 , cetyl trimethyl ammonium bromide (CTAB), 2,7-dihydroxynaphthalene (2,7-DHN) and NaOH under 30 min of reaction. The diameter of the individual particles in all the morphologies was B1-3 nm. The synthesized materials have been tested for catalysis and SERS studies. The catalysis study was examined taking different organic nitro compounds and the catalysis rate was found superior as compared to other reports. The surface enhanced Raman scattering (SERS) study was done taking Rose Bengal (R Be) as a probe molecule and the observed enhancement factor (EF) value was found superior or comparable to most of other noble metal NPs. The overall synthesis process was simple, less time consuming and cost-effective. The enhanced catalytic and SERS activities of the Os NCs might open up a new avenue for the application in other organic catalysis reactions, SERS based detection of environmentally important trace bio-molecules and sensors.

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Polymer Microgels for Catalysis

Terashima¹

2013

Encyclopedia of Polymer Science and Technology

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A polymer microgel is an intramolecularly cross-linked and discrete macromolecule, with the size ranging from nanometer to micrometer, to be fully dispersed, swollen, and soluble in various solvents (1-3), critically distinct from an insoluble macroscopic gel. The inner network structure of microgels provides multiple cavities with high loading capacity for various reagents. Focused on these features, microgels are so far employed for various applications, for example, as nanoreactors for catalysis, as nanocapsules (nanocarriers) for dye encapsulation, drug and gene delivery system, and as imaging agents (4-13).In this paper, recent advances in polymer-based microgels applicable to catalysis are comprehensively reviewed, especially focusing on the smart design of catalyst-embedded microgels and the unique catalytic performance.The study of these microgels began with the first report by Williams and co-workers in 1979 (14). They designed water-soluble microgels containing hydroxamic acid as a catalytic site by emulsion polymerization and discovered the excellent activity for the cleavage of 4-nitrophenylester. After the first example, several organic catalysts, such as acid (15,16), quaternary ammonium (17), and mercapto group (18), were incorporated into microgels. In the 2000s, polymer microgels with precisely controlled three-dimensional architectures have been combined with various catalyst species: metal complexes (19), metal nanoparticles (20), organocatalysts (21), and enzymes (22). The movement is attributed to the recent advances in living polymerization systems (23-28) that are quite effective to control primary structures of polymeric materials (3,10-13).Typical objectives for the encapsulation of catalysts into microgels are to improve the stability and the recyclability, with high activity and selectivity comparable to nonsupported (original) counterparts. The compatible performance originates from one of the inherent properties of microgels, that is of being "solubilized and/or dispersed" gels. Generally, insoluble gel-supported catalysts, typically based on silica and polystyrene gels, are useful for convenient catalyst recycle and product recovery (29), whereas they often result in low activity owing to the less accessibility of substrates to catalysts by the small surface area. In turn, soluble (non-cross-linked) polymer-supported catalysts often suffer catalyst leaching from the scaffolds to products during reactions, to spoil product recovery and catalyst recycle, though they perform activity comparable to nonsupported (original) counterparts for first cycle (30). In contrast, soluble (or dispersed) microgels solidly enclose catalysts in the cross-linked networks, similar to

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Catalytic Reduction of Aromatic Nitro Compounds by Coinage Metal Nanoparticles

Cited by 540 publications

References 9 publications

Natural reducing agents for electroless nanoparticle deposition: Mild synthesis of metal/carbon nanostructured microspheres

Natural reducing agents for electroless nanoparticle deposition: Mild synthesis of metal/carbon nanostructured microspheres

Enhanced catalytic and SERS activities of CTAB stabilized interconnected osmium nanoclusters

Polymer Microgels for Catalysis

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