Atomic-scale iron catalyst for the reductive N-formylation of nitroarenes under mild conditions

Abstract

The development of a mild and efficient non-noble metal heterogeneous catalytic system to achieve the conversion of nitroaromatic compounds into high-value products is of great significance, but it remains a substantial challenge. In this study, we present a mild and efficient protocol for the selective N-formylation of nitroarenes over a nitrogen-doped mesoporous carbon-supported iron-based catalyst Fe-opd-900, which was prepared by the method of high-temperature pyrolysis with the sacrifice of the template agent. Various substrates were successfully converted into the desired target products in moderate to excellent yields utilizing versatile formic acid as both a renewable hydrogen carrier and C1 source under mild conditions. The robust catalyst Fe-opd-900 could be used continuously for 15 times without significant loss in catalytic activity. The existence of atomically dispersed iron centers was confirmed by the characterizations of XPS, aberration-corrected HAADF-STEM, XANES, and EXAFS. Characterization and active sites studies indicate that the nitrogen species and highly dispersed Fe-N_x are crucial for the efficient activation of formic acid and the enhancement of catalytic performance. Based on kinetic experiments and control experiments, a reasonable reaction mechanism was proposed.