Carbon Microspheres Co-decorated with Nanosized Iron Sulfide and Magnetite Nanoparticles as a Magnetically Separable Heterogeneous Catalyst for the Green Synthesis of 4,4′-(Arylmethylene)bis(1H-pyrazol-5-ols)

Carbon microspheres co-decorated with nanosized iron sulfide and magnetite nanoparticles were synthesized by carbonizing an iron(III) sulfate-loaded polystyrene–divinylbenzene-based iminodiacetate-type cation-exchange resin in an inert atmosphere at 600°C for 4 h. The synthesized material was successfully employed as a magnetically separable heterogeneous catalyst for the green synthesis of 4,4′-(arylmethylene)­bis(1H-pyrazol-5-ols) via a one-pot pseudo-three-component condensation of aldehydes and 3-methyl-5-pyrazolone. The developed protocol offers several advantages, including high yields, short reaction times, simple work-up procedure, and catalyst reusability. Hence, it represents a valuable contribution to green and sustainable chemistry.