Epoxydation of Activated Olefins by Solid Bases

The epoxidations of 2-cyclohexen-1-one and β-isophorone by hydrogen peroxide and tert-butyl hydroperoxide have been investigated on basic catalysts including mild bases such as hydrotalcites activated in different conditions and fluorinated hydrotalcites, and two stronger bases, KF/Al2O3 and MgLa mixed oxides. The solids containing transition metal cations are unselective since they catalyze mainly the Fenton decomposition of H2O2 to O2. MgAl hydrotalcites are active for the epoxidation with tert-butyl hydroperoxide after decarbonation and rehydration of the surface. The catalytic properties are roughly dependent on the basic strength of the solids, and MgLa mixed oxides decarbonated at 823 K shows a higher activity for the epoxidation of isophorone by hydrogen peroxide comparable to that of titanosilicates.