Mesoporous silica SBA-15 functionalized with acidic deep eutectic solvent: A highly active heterogeneous N-formylation catalyst under solvent-free conditions

Mesoporous silica SBA-15 functionalized with N-methylpyrrolidonium-zinc chloride based deep eutectic solvent (DES) is found to be a more efficient and reusable catalyst for a convenient N-formylation of a variety of amines at room temperature. N-Formylation of primary, secondary as well as heterocyclic amines have been carried out in good to excellent yields by treatment with formic acid in low loading of DES/SBA-15 an environmentally benign catalyst for the first time. The DES/SBA-15 catalyst, which possesses both BrOnsted and Lewis acidities as well as an active SBA-15 support, makes this procedure quite simple, reusable, more convenient and practical. This catalyst was tolerant of a wide range of functional groups, and it can be reused for four runs without obvious deactivation.