Polyphosphoric acid supported on silica-coated NiFe2O4 nanoparticles: An efficient and magnetically-recoverable catalyst for N-formylation of amines

A rapid, green and simple method for the N-formylation of various aromatic amines with formic acid using polyphosphoric acid supported on silica-coated NiFe2O4 magnetic nanoparticles (NiFe2O4@SiO2–PPA) under solvent-free conditions at room temperature has been developed. The magnetic catalyst can be easily removed by a simple magnet and reused at least three times without any loss of its high catalytic activity. In addition to its facility, this protocol enhances product purity and promises economic and also environmental profits.