An Efficient and Practical Process for the Synthesis of Benzimidazole and Benzothiazole Derivatives Catalyzed by Layered Zirconium Phosphate: Effect of Calcinations Temperature.

In this work, layered zirconium phosphates were synthesized via a reflux method and calcined at different temperatures (200, 400, and 600°C). The catalytic activity of the prepared solids was tested in the condensation of o-phenylenediamine and o-aminothiophenol with various aromatic aldehydes. The reaction conditions were optimized taking into account some parameters that control the reaction, namely the nature and volume of the solvent and the mass of the catalyst. The results showed that solid ZrP-200 (layered zirconium phosphate calcined at 200°C) is the best performing catalyst for this reaction, because it has good catalytic activity and can be reused for at least five cycles with only a slight decrease in catalytic activity. In addition, a possible mechanism for the synthesis of benzimidazoles and benzothiazoles over ZrP-200 was proposed and discussed at the end of this study. [ABSTRACT FROM AUTHOR]