title: Immobilized iron oxide nanoparticles as stable and reusable catalysts for hydrazine-mediated nitro reductions in continuous flow.
abstract: An experimentally easy to perform method for the generation of alumina-supported Fe3O4 nanoparticles [(6±1) nm size, 0.67 wt %]and the use of this material in hydrazine-mediated heterogeneously catalyzed reductions of nitroarenes to anilines under batch and continuous-flow conditions is presented. The bench-stable, reusable nano-Fe3O4@Al2O3 catalyst can selectively reduce functionalized nitroarenes at 1 mol % catalyst loading by using a 20 mol % excess of hydrazine hydrate in an elevated temperature regime (150 °C, reaction time 2-6 min in batch). For continuous-flow processing, the catalyst material is packed into dedicated cartridges and used in a commercially available high-temperature/-pressure flow device. In continuous mode, reaction times can be reduced to less than 1 min at 150 °C (30 bar back pressure) in a highly intensified process. The nano-Fe3O4@Al2O3 catalyst demonstrated stable reduction of nitrobenzene (0.5 M in MeOH) for more than 10 h on stream at a productivity of 30 mmol h(-1) (0.72 mol per day). Importantly, virtually no leaching of the catalytically active material could be observed by inductively coupled plasma MS monitoring.
authors.affiliation: Christian Doppler Laboratory for Flow Chemistry (CDLFC) and Institute of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz (Austria).
authors.forename: Mojtaba Mirhosseini
authors.initials: MM
authors.lastname: Moghaddam
authors.forename: Bartholomäus
authors.initials: B
authors.lastname: Pieber
authors.forename: Toma
authors.initials: T
authors.lastname: Glasnov
authors.forename: C Oliver
authors.initials: CO
authors.lastname: Kappe
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D000814:Aniline Compounds / Q000737:chemistry; D002384:Catalysis; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006834:Hydrazines / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry; D010084:Oxidation-Reduction
chemical_list: D000814:Aniline Compounds; D006834:Hydrazines; D009574:Nitro Compounds; C029424:hydrazine; D000537:Aluminum Oxide; C023650:aniline; D052203:Ferrosoferric Oxide
keywords: anilines; heterogeneous catalysis; iron; microreactors; nanoparticles