Cation-exchanged montmorillonite (M(n+)-mont)-catalyzed Prins reaction

The Prins reaction of styrenes with paraformaldehyde or 1,3,5-trioxane in toluene in the presence of cation-exchanged montmorillonite (M(n+)-mont), which worked as a Bronsted acid catalyst, at 80 degrees C produced 4-aryl-1,3-dioxanes selectively in up to 99% isolated yield with a turnover number of up to 5.9 x 10(2). Among the examined 21 M(n+)-monts, Ce3+- and Fe3+-monts were revealed to be quite effective. Regeneration of the catalyst was confirmed with the Ce3+-mont, which could be effectively recycled at least three times. Many lanthanide metal ion-exchanged montmorillonites (Ln(3+)-monts) were prepared and characterized by X-ray powder diffraction (XRD) and temperature-programmed desorption of ammonia gas (NH3-TPD) methods.