Preparation and characterization of MNPs–PhSO3H as a heterogeneous catalyst for the synthesis of benzo[b]pyran and pyrano[3,2-c]chromenes

In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe 3 O 4 nanoparticles using tris(hydroxymethyl) aminomethane and 1,2-dichloroethane. Next, the synthesized nanocatalyst was fully characterized using FT-IR, XRD, TGA, VSM, SEM, and TEM. The results show that the synthesis of magnetic nanocatalyst has been successful with a range of 2–20 nm in size. Finally, the catalytic activity of this superparamagnetic nanocatalyst was explored for the synthesis of tetrahydrobenzo[ b ]pyran and 2-amino-5-oxo-4,5-dihydropyrano[3,2- c ]chromene-3-carbonitrile derivatives. The synthesized nanocatalyst has advantages such as non-toxicity, short reaction time, easy workup, cleaner reaction profiles under mild reaction conditions.