Green synthesis of metronidazole-based stabilized silica-coated Fe3O4 as a novel modified magnetic catalyst for the green solvent-free halogenation of aromatic compounds

Herein, Fe3O4 nanoparticle was first synthesized, then its surface was modified with tetraethyl orthosilicate, and finally, metronidazole was covalently fixed on its surface to synthesize Fe3O4@SiO2@(CH2)3-Metronidazole (FSCM). Synthesized materials were characterized. The catalytic activity of MNPs Fe3O4@SiO2@(CH2)3-metronidazole was studied by the aromatic bromination/iodination of aromatics under solvent-free conditions. Bromination/iodination products were characterized using 1H NMR and 13C NMR. The conversion yield of aniline to 4-bromoaniline using 0, 100, 200, 300, 400, and 500 mg of Fe3O4@SiO2@(CH2)3-Metronidazole at 25 min and 25 °C were trace, 76, 85, 96, 89, and 79 %, respectively. The catalyst showed high catalytic performance with excellent yields at short reaction times. The results showed that Fe3O4@SiO2@(CH2)3-Metronidazole can be used as a heterogeneous catalyst after 5 cycles without significant loss of catalytic activity (89%) for the bromination and iodination of aromatic hydrocarbons with KBr/KI.