Chemoselective Hydrogenation of Functionalized Nitroarenes to Anilines
Remarkable Effect of Alkalis on the Chemoselective Hydrogenation of Functionalized Nitroarenes over High-Loading Pt/FeOx Catalysts.
Chem. Sci. 2017;
18 September 2017 (online)
A sodium-containing FeOx-supported platinum catalyst (Na-Pt/FeOx) was prepared by mixing H2PtCl6 and Fe(NO3)3 with (NH4)2CO3 in water, followed by the treatment with NaNO3, calcination, and reduction with hydrogen (eq.1). Na-Pt/FeOx catalyzed the chemoselective hydrogenation of substituted nitroarenes under hydrogen pressure to afford the corresponding anilines in 95–97% yield (eq. 2). In the hydrogenation of 3-nitrostyrene, Na-Pt/FeOx promoted the hydrogenation of the nitro group to give 3-aminostyrene in 95% conversion with 98% selectivity (eq. 3). The catalyst was reused three times without significant loss of its catalytic activity or chemoselectivity.
Other alkali-metal-containing Pt/FeOx catalysts (Li-Pt/FeOx and K-Pt/FeOx) also promoted the selective hydrogenation of 3-nitrostyrene to 3-aminostyrene in 96 to >99% conversion and 94–95% selectivity. Compared with alkali-metal-containing catalysts, alkali-metal-free Pt/FeOx showed a lower selectivity (99% conversion and 66% selectivity). The authors have previously reported the chemoselective hydrogenation of functionalized nitroarenes to the corresponding anilines by using FeOx-supported platinum catalysts prepared from H2PtCl6, Fe(NO3)3, and Na2CO3 (Nat. Commun. 2014, 5, 5634).