Mesoporous Borated Zirconia: A Solid Acid–Base Bifunctional Catalyst

The development and use of reusable solid catalysts for the selective organic transformation in solvent‐free or environmentally benign solvent media is the key interest of modern frontier science. Herein a facile low temperature aqueous solution based chemical route for the synthesis of mesoporous borated zirconia, an acid–base bifunctional solid catalyst, using aqueous zirconium ammonium carbonate complex and borax in presence of cetyltrimethylammonium bromide is presented. The material has a very high surface area and acidity with weak basicity. The catalytic activity of the material was investigated for the solvent‐free Knoevenagel condensation reaction of benzaldehyde/substituted benzaldehyde and malononitrile/cyano ethylacetate to confirm the acid–base bifunctionality. High yield (>90 %) of the corresponding benzylidene was obtained within 15–30 min at room temperature. The evidence that the high catalytic activity is a result of acid–base bifunctionality of the synthesized borated zirconia material was further supported by performing Claisen–Schmidt condensation of benzaldehyde and acetophenone. The methodology was also extended for targeted synthesis of cinnamyl ethyl ester and coumarin or coumarin ester; and resulted in a good yield.