Synthesis of N- aryl and N -heteroaryl hydroxylamines via partial reduction of nitroarenes with soluble nanoparticle catalysts

Highly efficient and selective partial reduction of nitroarenes to N-arylhydroxylamines catalysed by phosphine oxide-decorated polymer immobilized ionic liquid stabilized ruthenium nanoparticles

“…The synthesis of N-arylhydroxylamines is of considerable interest as they are important intermediates to high value products including pharmaceuticals such as acetaminophen and pyraclostrobin and bioactive derivatives of the antibiotics azomycin and chloramphenicol [1][2][3][4][5][6][7][8][9][10][11], fine chemicals [12][13][14], polymerisation inhibitors [15][16] as well as useful reagents in organic synthesis as they undergo cyclizations, rearrangements and metal-catalysed additions to multiple bonds [17][18][19][20][21][22][23]. While N-arylhydroxylamines can be prepared by metal catalysed Narylation of a hydroxylamine [24][25][26][27] or the catalytic reduction of aldoximines [28][29][30][31][32][33], the selective reduction of nitroarenes is potentially the most versatile and convenient [34][35][36][37][38][39][40][41][42][43][44][45]…”

“…To this end, while there has been a plethora of reports of the reduction of nitroarenes to the corresponding aniline, selective partial reduction to the thermodynamically unfavourable N-arylhydroxylamine remains a challenge. The most common protocols involve stoichiometric reductions with zinc, tin, antimony or bismuth [34][35][36][37][38][39] and catalytic reductions using either heterogeneous or nanoparticle-based catalysts such as Rh/C [40][41], Pt/SiO 2 [42], RuNP/CNT [43], RuNP/polystyrene [44], PtNP/ Amberlite IRA 900 resin [45], c-PtNP/C [46], IrNP/polystyrene [47], solid-supported PtNP deactivated by DMSO or amine [48][49], silica-supported PdNP [50] and ultra-small palladium nanoclusters [51]. Despite the popularity of this approach, they all suffer one or more drawbacks including, the use of large amounts of expensive noble metal catalyst or stoichiometric quantities of earth abundant metal reagent, the need for an additive, low isolated yields, poor selectivity and functional group tolerance as well as slow rates, the need for harsh reaction conditions and poor environmental credentials due to the use of toxic and/or hazardous reagents and the generation of large amounts of by-product.…”

Biomolecule-Mediated Generation of Ru Nanocatalyst for Sustainable Reduction of Nitrobenzene

“…The widely studied methods for the generation of nanodimensional Ru catalyst utilize the conventional reduction process with drastic reaction conditions. 11,12…”

“…The widely studied methods for the generation of nanodimensional Ru catalyst utilize the conventional reduction process with drastic reaction conditions. 11,12 Reduction using biomolecules has gradually captured the limelight of researchers due to the increasing environmental, economic, as well as industrial concern. In this connection, plant extract or plant-mediated materials have revealed their capability to convert metal ions into their nanostate often through a simple process without requirement of any rigorous experimental setup.…”

“…Although ruthenium is a low-cost material, a recyclable Ru-based catalyst would make the methodology many-fold cost-effective, environment-friendly, and industrially efficient. The widely studied methods for the generation of nanodimensional Ru catalyst utilize the conventional reduction process with drastic reaction conditions. , …”