Facile Reduction of Nitroarenes into Anilines and Nitroalkanes into Hydroxylamines via the Rapid Activation of Ammonia⋅ Borane Complex by Supported Gold Nanoparticles

Abstract

Gold nanoparticles supported on titania catalyse, even at a ppm loading level, the quantitative reduction of nitroarenes into anilines and nitroalkanes into alkylhydroxylamines by the ammonia· borane complex. No dehalohalogenation was seen in the case of chloro-or bromonitroarenes, while ester, cyano, or carboxylic acid functionalities also remain intact. The nitroarene to aniline reduction pathway does not require nitrosoarenes as intermediate products.

Tandem Dehydrogenation of Ammonia Borane and Hydrogenation of Nitro/Nitrile Compounds Catalyzed by Graphene-Supported NiPd Alloy Nanoparticles

“…Other amino-nitrobenzenes (20 and 22) were reduced similarly to 1,3-dinitrobenzene, producing the corresponding diamine products (Table 1, entries 11 and 12). The selective reduction of -NO 2 was better demonstrated in aromatic compounds bearing other reducible substituents such as 1-bromo-4-nitrobenzene (24) and methyl 2-hydroxy-4- nitrobenzoate (26). They were all reduced to the related amine products (>99% conversion in 5 min) ( Table 1, entries 13 and 14), and the Br-or ester group showed no obvious effect on the NO 2 reduction kinetics.…”

Highly efficient and selective reduction of nitroarenes into anilines catalyzed by gold nanoparticles incarcerated in a nanoporous polymer matrix: Role of the polymeric support and insight into the reaction mechanism

“…nitrostyrene, nitrobenzaldehydes and nitrobenzonitriles, was thus successfully accomplished. Other authors showed later that the reaction could be carried out under milder conditions using alternative and more efficient reductants as the ammonia-borane complex [7], sodium borohydride [8], isopropanol [9], silanes [10], CO/H 2 O [11] (WGS reaction as source of dihydrogen). Intriguingly UV-Vis light irradiation of the AuNPsTiO 2 catalysts produced the selective reduction of nitrobenzenes to azobenzenes [12].…”

‘‘Hydrogen-Free’’ Hydrogenation of Nitrobenzene Over Cu/SiO2 Via Coupling with 2-Butanol Dehydrogenation

“…Issues of sustainable production and safe handling are now drivers for alternative sources of hydrogen and/or hydrogen donors. Several hydrogen carriers including hydrazine [3], ammonia-borane complexes [4], esters [5], alcohols [6] and acids [7] have been employed in homogeneous and heterogeneous transfer hydrogenation but application is hampered due to the required separation steps for catalyst reuse. A continuous heterogeneous catalytic system that combines dehydrogenation with hydrogen release that is utilised in hydrogenation represents an alternative approach that circumvents the requirement for an external hydrogen supply.…”