[en] The immobilized sulfonic acid on silica-layered magnetite was successfully synthesized and characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy, scanning electron microscopy and thermogravimetric analyses. The prepared Fe₃O₄@SiO₂-SO₃H MNPs were used as an efficient solid acidic nanocatalyst toward successful formylation of structurally diverse aliphatic and benzylic primary/secondary alcohols using formic acid under oil bath conditions (60 °C). The product, formyl esters, was obtained in 76–92% yields within 1–20 min. The sulfonated nanocatalyst was easily recovered by an external magnetic field and reused for five consecutive cycles without significant loss of its catalytic activity. Graphical Abstract:

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