Aluminatesulfonic acid nanoparticles: synthesis, characterization and application as a new and recyclable nanocatalyst for the Biginelli and Biginelli-like condensationsElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ra01406a

A new, efficient and recyclable nanocatalyst, aluminatesulfonic acid, was prepared and used as a heterogeneous solid acid catalyst for the synthesis of a variety of Biginelli compounds, such as dihydropyrimidinones and dihydropyrimidinthiones, and Biginelli-like products, such as octahydroquinazolinone, pyrimido[4,5- d ] pyrimidine and tetrahydropyrimidine derivatives, under solvent-free conditions. This acid catalyst was characterized using FT-IR, X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG), energy dispersive X-ray analysis (EDAX) and UV diffusion/reflectance. The catalyst showed high thermal stability and good reusability. In addition, compared to the classical Biginelli reactions, this method has the advantage of consistently high yields, short reaction times, simple workup and an inexpensive and reusable catalyst. A new, efficient and recyclable nanocatalyst, aluminatesulfonic acid, was prepared and used as a heterogeneous solid acid catalyst for the synthesis of a variety of Biginelli and Biginelli-like products under solvent-free conditions.