Defect-mediated selective hydrogenation of nitroarenes on nanostructured WS₂

Abstract

Colloidal 2H-WS2 nanostructures catalyze selective hydrogenation of substituted nitroarenes to anilines with molecular hydrogen, where sulfur vacancies and tungsten-terminated edges play key roles in enabling functional group selectivity.

Reduction of Nitroarenes via Catalytic Transfer Hydrogenation Using Formic Acid as Hydrogen Source: A Comprehensive Review

“…NaBH 4 or hydrosilanes, [17–25] hydrazine hydrate, [17,26–30] organic reagents ( e. g . alcohol, glycerol or formic acid) [17,31–33] and more recently, boron reagents [34–35] . Other methods based on reduced sulfur reagents like elemental sulfur, [36–37] dithionite [38] or sulfides [39] are useful for the reduction of nitro group, being particularly convenient for the selective reduction of polynitroarenes.…”

“…From Green Chemistry point of view, the catalytic hydrogenation have received enormous attention by their improvements compared to Bechmap's reduction; [17] however, this type of strategies presents some drawbacks such as the use of specialized equipment and safety issues related to H 2 storage, the manipulation of flammable hydrogen gas and the use of hazardous reagents and sophisticated organometallic complexes/nanometallic catalyst, which limit its practicality and economy. Moreover, the catalytic hydrogenation involves a significant lack of chemoselectivity for nitroarenes containing other reducible groups such as carbonyl, nitro, nitrile, halides, multiple bonds or heterocycles [17,41] . In order to improve the selectivity of classical catalyst, the construction of bimetallic catalyst such as Pt−Fe/TiO 2 , Rh−Fe/C, Pb−Pd/CaCO 3 have permitted the selective reduction of nitro group in nitro‐compounds containing benzylic, multiple bonds, carbonyl, nitrile and imine moieties [42–43a] .…”

“…[8][9] Alternatively to Bechamp's reduction, the nitro group into nitroarene can be reduced to corresponding aromatic amines through two chemical processes: (i) the catalytic direct hydrogenation using molecular hydrogen (H 2 ) or (ii) the hydrogenation transfer using a hydrogen source. The first is catalyzed by specific transition metals such as iron, nickel, palladium or platinum in presence of molecular hydrogen under special pressure conditions, [8b,10-16] whereas the second strategy employs hydrogen sources for the transfer hydrogenation process such as hydrides (e. g. NaBH 4 or hydrosilanes, [17][18][19][20][21][22][23][24][25] hydrazine hydrate, [17,[26][27][28][29][30] organic reagents (e. g. alcohol, glycerol or formic acid) [17,[31][32][33] and more recently, boron reagents. [34][35] Other methods based on reduced sulfur reagents like elemental sulfur, [36][37] dithionite [38] or sulfides [39] are useful for the reduction of nitro group, being particularly convenient for the selective reduction of polynitroarenes.…”

“…[34][35] Other methods based on reduced sulfur reagents like elemental sulfur, [36][37] dithionite [38] or sulfides [39] are useful for the reduction of nitro group, being particularly convenient for the selective reduction of polynitroarenes. From Green Chemistry point of view, the catalytic hydrogenation have received enormous attention by their improvements compared to Bechmap's reduction; [17] however, this type of strategies presents some drawbacks such as the use of specialized equipment and safety issues related to H 2 storage, the manipulation of flammable hydrogen gas and the use of hazardous reagents and sophisticated organometallic complexes/nanometallic catalyst, which limit its practicality and economy. Moreover, the catalytic hydrogenation involves a significant lack of chemoselectivity for nitroarenes containing other reducible groups such as carbonyl, nitro, nitrile, halides, multiple bonds or heterocycles.…”

“…Moreover, the catalytic hydrogenation involves a significant lack of chemoselectivity for nitroarenes containing other reducible groups such as carbonyl, nitro, nitrile, halides, multiple bonds or heterocycles. [17,41] In order to improve the selectivity of classical catalyst, the construction of bimetallic catalyst such as PtÀ Fe/TiO 2 , RhÀ Fe/C, PbÀ Pd/CaCO 3 have permitted the selective reduction of nitro group in nitrocompounds containing benzylic, multiple bonds, carbonyl, nitrile and imine moieties. [42-43a] Other inconvenient of catalytic hydrogenation is the high susceptibility of the C-halide bonds, in particular the CÀ Br and CÀ I bonds, that suffer hydrodehalogenation to form CÀ H bond mediated by oxidative addition of metal (Pt, Pd, Rh) to CÀ X bond.…”