Hydrotalcite reconstructed by in situ rehydration as a highly active solid base catalyst and its application in aldol condensations

Abstract

Reconstructed hydrotalcite is a highly active heterogeneous base catalyst for a wide variety of reactions. Herein, we report a procedure to effectively prepare the reconstructed hydrotalcite. Mg–Al mixed oxide, which originates from hydrotalcite, is added directly to the aqueous-phase reaction system of the aldol condensation without the protection of an inert gas. Under the reaction conditions, the reconstructed hydrotalcite is in-situ generated, and is used as a catalyst for then aldol condensation as soon as it forms, resulting in the elimination of the deactivation of reconstructed hydrotalcite. The experimental results showed that the in-situ reconstructed hydrotalcite had higher catalytic activity and water tolerance. The work provides a simple and effective method for reconstructed hydrotalcite.