Reduction of Nitroarenes into Aryl Amines and N-Aryl hydroxylamines via Activation of NaBH4 and Ammonia-Borane Complexes by Ag/TiO2 Catalyst

Andreou, Dimitrios; Iordanidou, Domna; Tamiolakis, Ioannis; Armatas, Gerasimos S.; Lykakis, Ioannis N.

doi:10.3390/nano6030054

Cited by 39 publications

(30 citation statements)

References 41 publications

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“…Silver nanoparticles (Ag NPs) have recently received extensive attention from researchers and developers due to their attractive optical, electronic, and catalytic properties and excellent antimicrobial activity [ 1 , 2 , 3 ]. Ag NPs exhibit strong antibacterial activity toward a broad range of microorganisms [ 4 ], but simultaneously possess a remarkably low human toxicity.…”

Section: Introductionmentioning

confidence: 99%

Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity

et al. 2016

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A facile, efficient, and eco-friendly approach for the preparation of uniform silver nanoparticles (Ag NPs) was developed. The synthesis was conducted in an aqueous medium exposed to microwave irradiation for 8 min, using laboratory-prepared, water-soluble quaternized carboxymethyl chitosan (QCMC) as a chemical reducer and stabilizer and silver nitrate as the silver source. The structure of the prepared QCMC was characterized using Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (NMR). The formation, size distribution, and dispersion of the Ag NPs in the QCMC matrix were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis), transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM) analysis, and the thermal stability and antibacterial properties of the synthesized QCMC-based Ag NPs composite (QCMC-Ag) were also explored. The results revealed that (1) QCMC was successfully prepared by grafting quaternary ammonium groups onto carboxymethyl chitosan (CMC) chains under microwave irradiation in water for 90 min and this substitution appeared to have occurred at -NH2 sites on C2 position of the pyranoid ring; (2) uniform and stable spherical Ag NPs could be synthesized when QCMC was used as the reducing and stabilizing agent; (3) Ag NPs were well dispersed in the QCMC matrix with a narrow size distribiution in the range of 17–31 nm without aggregation; and (4) due to the presence of Ag NPs, the thermal stability and antibacterial activity of QCMC-Ag were dramatically improved relative to QCMC.

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Section: Introductionmentioning

confidence: 99%

Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity

et al. 2016

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“…The final reduction step converting the hydroxylamine into an amine is unlikely to be the result of excess NaBH 4 , since phenylhydroxylamine is inert to this reductant (Figure S8 in the Supporting Information). In general, nitroaromatics also do not react with NaBH 4 spontaneously and instead require a catalyst such as Ag/TiO 2 or transition‐metal sulfides to promote formation of the corresponding amines . The inability of NaBH 4 to reduce nitro‐ and hydroxylamine‐containing aromatics provided the first opportunity to test the continuous turnover of an IYD derivative designed to act as an NR.…”

Section: Methodsmentioning

confidence: 99%

Conversion of a Dehalogenase into a Nitroreductase by Swapping its Flavin Cofactor with a 5‐Deazaflavin Analogue

Boucher

Rokita

2017

Angewandte Chemie

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Natural and engineered nitroreductases have rarely supported full reduction of nitroaromatics to their amine products,a nd more typically,t ransformations are limited to formation of the hydroxylamine intermediates.Efficient use of these enzymes also requires ar egenerating system for NAD-(P)H to avoid the costs associated with this natural reductant. Iodotyrosine deiodinase is am ember of the same structural superfamily as many nitroreductases but does not directly consume reducing equivalents from NAD(P)H, nor demonstrate nitroreductase activity.H owever,e xchange of its flavin cofactor with a5 -deazaflavin analogue dramatically suppresses its native deiodinase activity and leads to significant nitroreductase activity that supports full reduction to an amine product in the presence of the convenient and inexpensive NaBH 4 .

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“…A common route for obtaining N ‐aryl hydroxylamines is the selective reduction of nitroarenes which can be achieved using for example zinc dust in aqueous NH 4 Cl, hydrazine, or catalytic hydrogenation . Another method of choice is the use of sodium borohydride which usually requires the presence of noble metal activators such as silver, platinum, or palladium . Noble metal‐free alternatives have also recently emerged, aiming at developing more sustainable chemical processes …”

Section: Introductionmentioning

confidence: 99%

Selective Conversion of Nitroarenes to N‐Aryl Hydroxylamines Catalysed by Carbon‐Nanotube‐Supported Nickel(II) Hydroxide

et al. 2017

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International audienceA novel nanohybrid was assembled by a layer-by-layer strategy that permitted the immobilization of nickel(II) hydroxide on multi-walled carbon nanotubes. The heterogeneous catalyst was used for the reduction of a wide variety nitroaromatics to hydroxylamines in a binary solvent mixture (tetrahydrofuran/ water), in the presence of sodium borohydride and under mild conditions. The reaction is highly selective as it afforded cleanly the expected aromatic hydroxylamines in the presence of other sensitive groups such as halogens, esters, double bonds or nitriles. The catalyst could also be readily recycled by a simple centrifugation and reused in subsequent reduction reactions with no decrease in catalytic activities, over five cycles. Analysis of the spent catalyst indicated neither alteration in the morphology, metal-content, nor oxidation state of the carbon nanotube-supported nickel(II). The catalytic nanohybrid assembly reported in this work thus compares favorably with known systems, as it is very stable, operates at room temperature with limited nickel loading (0.8 mol%), and selectively leads to N-aryl hydroxylamines without the formation of the corresponding anilines

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Reduction of Nitroarenes into Aryl Amines and N-Aryl hydroxylamines via Activation of NaBH4 and Ammonia-Borane Complexes by Ag/TiO2 Catalyst

Cited by 39 publications

References 41 publications

Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity

Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity

Conversion of a Dehalogenase into a Nitroreductase by Swapping its Flavin Cofactor with a 5‐Deazaflavin Analogue

Selective Conversion of Nitroarenes to N‐Aryl Hydroxylamines Catalysed by Carbon‐Nanotube‐Supported Nickel(II) Hydroxide

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