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 prod uced 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+)-mo nts, Ce3+- and Fe3+-monts were revealed to be quite effective. Regener ation 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 characteri zed by X-ray powder diffraction (XRD) and temperature-programmed desor ption of ammonia gas (NH3-TPD) methods.