The development of heterogeneous catalysts to promote selective organic reactions is a field of growing interest. Whereas heterogeneous acid catalysis has been applied to a good number of processes, basic catalysis is far less developed. Oxidation reactions are among the most interesting processes from the industrial point of view, and epoxidation is one of the most important oxidation reactions, given the usefulness of epoxides as synthetic intermediates. The epoxidation of electron-deficient alkenes can be carried out with hydroperoxides in the presence of a base. The catalytic activity of the hydrotalcites in the epoxidation of electron-deficient alkenes depends on the basicity of the solid, which can be controlled by the Mg/A1 ratio. The highest catalytic activity corresponds to a hydrotalcite with a ratio Mg/A1 = 3. The solid with this Mg/Al ratio is also the catalyst with the highest number of basic sites, as measured by phenol adsorption in liquid phase. The epoxide/dioxolane selectivity also increases with the basicity of the solid and the reaction time, showing the reversibility of the reaction of dioxolane formation. The hydrotalcite is recoverable and reusable at least twice without the loss of catalytic activity.

Peer reviewed