Room temperature selective reduction of nitrobenzene to azoxybenzene over magnetically separable urchin-like Ni/Graphene nanocomposites

Magnetically recyclable Ni/Graphene (Ni/G) nanocomposites were synthesized via an in situ reduction growth process for selective reduction of nitroarenes into corresponding azoxybenzene at room temperature and at atmospheric pressure. Here, hydrazine hydrate (N2H4 center dot H2O) is used as the reducing agent which generates harmless by-products such as N-2 and water. The catalyst, when used under controlled reaction conditions, exhibits a 100% conversion and selectivity to the target product without the use of any external additives (turnover number 36.2). Under the optimized conditions, a variety of structurally different nitroarenes were selectively transformed to their corresponding azoxy products in high conversions. Furthermore, a high stability and recyclability of the catalyst were also observed under the investigated conditions (93% conversion, 100% selectivity after the 4th reuse). (C) 2016 Elsevier Inc. All rights reserved.