Synthesis of aniline from dinitrogen and benzene mediated by magnesium oxide supported sodium hydride.

Abstract

The activation and valorization of inert molecules (e.g., dinitrogen (N₂), alkanes, and alkenes) for the synthesis of nitrogen-containing organic compounds have long been a highly sought-after goal in chemistry. However, it remains a formidable challenge, stemming from the inherent chemical inertness of the robust N ≡ N and C-H bonds, as well as the competitive adsorption and activation of reactants. Consequently, examples of direct C-N bond formation using N₂ and alkanes/alkenes as feedstocks remain exceptionally scarce. Herein, we report that sodium hydride supported on magnesium oxide (NaH/MgO) possesses unique multiple reactive sites, which enable the conversion of N₂ and unactivated arenes and facilitate C-N bond formation. The synergistic interplay between sodium, magnesium, and hydride species at the NaH/MgO interface plays a pivotal role in the reduction of N₂ to NH_x species. These reactive NH_x intermediates then deprotonate the aryl C-H bond, attack the alkali-interacted aryl ring, and drive the formation of sodium anilide on the surface. Subsequent protonation of sodium anilide yields aniline with high selectivity (>90%). This work demonstrates the feasibility of transforming N₂ and simple arenes into key nitrogen-containing organic compounds via a solid surface-mediated process, thereby opening ample room for developing heterogeneous catalysts for the transformation of N₂ and organic substrates.