The acidic-free synthesis of 2-nitropyrrole and 2,4-dinitropyrrole using choline nitrate as regent and Pd@C3N4 as photocatalyst

Escaping from conventional hazardous methods, an innovative, acidic-free approach for the synthesis of nitro-heterocycles was realized through photocatalytic nitration using Pd-doped g-C3N4. In this method, chlorate nitrate was initially utilized as a reagent. Spectral analysis and electronic microscopy confirmed the successful doping of Pd nanoparticles (NPs) onto the g-C3N4 surface, which subsequently enhanced the photocatalytic performance. The photogenerated electrons and Pd NPs played pivotal roles in the production of nitro-products. The reactive intermediate, NO2+, derived from nitrate, can be captured and elucidated through the shifts in cyclic voltammetry (CV) curves. Herein the synthesis of 2-nitropyrrole and 2,4-dinitropyrrole was achieved through the nitration of chlorate nitrate in a friendly manner. Moreover, the composite photocatalyst could be readily isolated and recycled in next four tests, demonstrating its practicality and sustainability in photocatalytic applications.