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

Abstract

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

Reduction of Nitro Compounds Using 3d-Non-Noble Metal Catalysts

“…A particular catalyst system for the synthesis of N -arylhydroxylamines from nitroarenes was published by E. Gravel, E. Doris, and co-workers in 2017 . Here, Ni­(II) hydroxide was supported on carbon-nanotubes by a layer-by-layer strategy.…”

“…(a) Structure of DANTA with its hydrophilic head and hydrophobic tail, (b) structure of PDADMAC, and (c) schematic structure of the architecture of the catalyst reported by E. Gravel, E. Doris, and co-workers. Reproduced with permission from ref . Copyright 2017 Wiley-VCH.…”

“…A particular catalyst system for the synthesis of Narylhydroxylamines from nitroarenes was published by E. Gravel, E. Doris, and co-workers in 2017. 297 Here, Ni(II) hydroxide was supported on carbon-nanotubes by a layer-bylayer strategy. Diacetylene-nitrilotriacetic acid amphiphiles (DANTA, Figure 45 a Finally, Ni NPs were added to form the active material (Figure 45c), which showed very high selectivity toward Narylhydroxylamines.…”

Bimetallic ruthenium–rhodium particles supported on carbon nanotubes for the hydrophosphinylation of alkenes and alkynes

“…In addition, these transformations often necessitate heat activation. 9 With these features in mind, and as part of our longstanding interest in semi-heterogeneous 10 and heterogeneous processes, 11,12 we report here the use of a recyclable bimetallic ruthenium-rhodium (RuRh) catalyst supported on carbon nanotubes (CNTs) for the catalysis of the hydrophosphinylation reaction under mild conditions (Scheme 1).…”

Direct aerobic oxidation of alcohols into esters catalyzed by carbon nanotube–gold nanohybrids

“…Our group has long been involved in the design of catalytic nanohybrids made by the assembly of metallic nanoparticles on carbon nanotubes (CNTs). 2 In fact, nanostructured carbon allotropes such as CNTs have emerged as promising supports that provide unique advantages including stability, inertness, high specific surface area, and chemically tunable topography. 3 In addition, CNTs act as synergistic platforms capable of enhancing the performances of the supported catalytic metal.…”