Gum acacia-CuNp-silica hybrid: an effective, stable and recyclable catalyst for reduction of nitroarenes

A gum acacia-CuNp-silica hybrid behaved as an efficient catalyst for the sodium borohydride reduction of nitroarenes. The hybrid (3 x 10(-3) g) in combination with 0.1MNaBH(4) was capable of reducing 4-nitrophenol into 4-amino phenol within 2.3 minutes at roomtemperature. The reduction did not require any exclusion of oxygen or moisture. The catalyst retained its full activity even after one month storage under the laboratory conditions. It could be easily recycled for six repeated cycles with only marginal loss of catalytic activity. The conditions for borohydride reduction of 4-nitrophenol have been optimized, and under these conditions the reduction of 4-nitroaniline and 4-nitrobenzoic acid was possible within 3.15 and 8.3 minutes, respectively.