Reconstructed Hydrotalcite as a Heterogeneous Base Catalyst

Significance

Reconstructed hydrotalcites were developed as a base catalyst for the aldol condensation. The calcination of the parent hydrotalcite 1 led to removal of the surface HCO₃ ^- and interlayer CO₃ ^2- species to give the Mg-Al mixed oxide 2. Treatment of the Mg-Al mixed oxide 2 with water gave the reconstructed hydrotalcite 3. The surface HCO₃ ^- species and interlayer CO₃ ^2- anion of the parent hydrotalcites were substituted with OH^- anions in the reconstructed form. The reconstructed hydrotalcite 3 served as heterogeneous base catalyst for the aldol reactions of aldehydes in the presence of water.