Sustainable protocol for the reduction of nitroarenes by heterogeneous Au@SBA‐15 using NaBH4 under flow conditions

Abstract

Gold‐incorporated SBA‐15 catalyst was prepared by a solvent‐free ball milling approach. The catalyst showed high reactivity and selectivity in the reduction of a variety of nitroarenes to anilines operating in absolute EtOH using NaBH4 as reducing agent. The catalyst was reused in batch conditions over 5 consecutive runs without detecting any losses of activity and selectivity. Considering the high chemical stability and reusability of the catalytic system, a continuous flow protocol was also investigated and defined in order to minimize the production of waste associated to the process and optimize the continuous reuse of the catalyst. Benefits of flow conditions were proven by TON values that increased from 47.5 to 1902 and also by the minimization of both leaching (9.5 vs 1 ppm) and E‐factor values (8 vs 23 in batch).