Herein, formylation of structurally different amines and alcohols with ethyl formate was carried out in the presence of a catalytic proportion of sulfonic acid supported on polydopamine (PDA)-encapsulated Fe3O4 nanoparticles as a heterogeneous, recyclable, and greatly efficient catalyst; this method provided the corresponding N-formyl compounds in good to excellent yields under solvent-free conditions. The magnetically catalytic system was recovered, by-passing the time-consuming filtration operation using an external magnet device. This procedure also increases the purity of the product and promises economic and ecological advantages. Furthermore, the recovery and reuse of the catalyst was demonstrated five times without detectable loss in the activity.
