Efficient Reduction of Nitroarenes over Nickel‐Iron Mixed Oxide Catalyst Prepared from a Nickel‐Iron Hydrotalcite Precursor

Abstract

Nickel-iron mixed oxide prepared from a nickel-iron hydrotalcite precursor was found to be a highly efficient catalyst for the chemoselective reduction of nitroarenes under mild reaction conditions.Keywords: aromatic amines; chemoselectivity; hydrogen transfer; hydrotalcites; nitroarenes; reduction Aromatic amines are an important class of compounds frequently used as key intermediates in the synthesis of pharmaceutical products, dyestuffs and polymers. Various methods have been reported for the preparation of aromatic amines from the corresponding aromatic nitro compounds. Compared to the generally used methods [1] that need either strong acid medium, which corrodes the reaction equipment seriously, or hazardous molecular hydrogen and highpressure reactors, catalytic transfer hydrogenation, as a safer and greener way, has attracted more and more attention.[2] Hydrazine hydrate is widely employed as hydrogen donor in catalytic transfer hydrogenation because the hydrazine reduction produces harmless by-products such as nitrogen gas and water. The usual catalysts used in the hydrazine reduction of nitroarenes are zinc, [3] magnesium, [4] FeCl 3 ·6 H 2 O-activated carbon, [5] ironA C H T U N G T R E N N U N G (III) oxide [6] and iron oxide hydroxide. [7] Recently magnesium-iron mixed oxide prepared from a magnesium-iron hydrotalcite-like precursor has also been reported as an effective catalyst for the hydrazine reduction of aromatic nitro compounds.[8]Hydrotalcite-like compounds belong to the anionic clay materials and have the general formulawhere M is a metal and A is an anion).[9] Thermal decomposition of hydrotalcite-like compounds can form highly thermally stable and highly dispersed mixed oxides with large surface area and obvious basic properties, as well as redox properties if a reducible metal is contained in the network. In recent years, mixed oxides prepared from hydrotalcite-like precursors have received increasing interest because these oxides often display good activity and selectivity in various reactions. [10] Nickel-iron hydrotalcite, a very important member of the hydrotalcite family, has been widely researched [11] and applied as adsorbent [12] and catalyst [13] over the past decade. However, it is surprising that, until now, there are few reports about the application of nickeliron mixed oxide obtained from a nickel-iron hydrotalcite precursor as catalyst in the organic synthesis. [14] In continuation of our interest in exploring the applications of mixed oxides prepared from hydrotalcite-like precursors in reduction, herein, we report for the first time the use of nickel-iron mixed oxide from a nickel-iron hydrotalcite-like precursor as catalyst in the reduction of nitroarenes to prepare aromatic amines (Scheme 1). We expect that the present study could play a role of a catalyst which will accelerate the investigation of nickel-iron mixed oxide as a catalyst in organic synthesis.As shown in Table 1, various nitroarenes with different substituted groups have been successfully reduce...

In Situ Generated Iron Oxide Nanocrystals as Efficient and Selective Catalysts for the Reduction of Nitroarenes using a Continuous Flow Method

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Polymer supported palladium nanocrystals as efficient and recyclable catalyst for the reduction of nitroarenes to anilines under mild conditions in water

“…Numerous protocols for the reduction of aromatic nitro compounds have been reported in the literature [2][3][4][5][6][7]. They include: 1) hydrogenation under H 2 at various pressures promoted by various catalysts [8], such as Pt/C [9], Rh 3 Ni 1 [10], Pd/C [11][12][13], Pd [14,15] and Rh [16] nanoparticles; 2) catalytic reduction in the presence of CO and H 2 O [17] and photocatalytic hydrogenation [18]; 3) catalytic transfer hydrogenation promoted, for example, by Cu [19], Pd [20], palladium/graphene [21], Au [22], Ru [23] or Fe 3 O 4 -Ni [24] nanoparticles with reducing agents other than molecular hydrogen [25,26], including hydrazine [27][28][29][30][31][32], silanes [33,34] and sodium borohydride [35][36][37][38][39][40][41]. In this last case, large use of Au based catalysts has been explored [42].…”

Noncovalently functionalized carbon nanotubes immobilized Fe–Bi bimetallic oxides as a heterogeneous nanocatalyst for reduction of nitroaromatics

“…However, these catalysts are either less active or easily deactivated in cycles, and some of them are made from less common iron precursor, such as Fe(acac) 3 . Due to the synergistic effects between different metals, to design bimetallics [31] and bimetallic oxides [32] catalysts is considered as a promising strategy for producing the catalysts with high activity, good selectivity and low cost.…”