Ag@TiO2 Nanocomposite as an Efficient Catalyst for Knoevenagel Condensation

Mostafa Sayed; Zhipeng Shi; Farzad Gholami; Pedram Fatehi; Ahmed I A Soliman

doi:10.1021/acsomega.2c03852

Ag@TiO₂ Nanocomposite as an Efficient Catalyst for Knoevenagel Condensation

ACS Omega. 2022 Sep 1;7(36):32393-32400. doi: 10.1021/acsomega.2c03852. eCollection 2022 Sep 13.

Authors

Mostafa Sayed^{1

2}, Zhipeng Shi¹, Farzad Gholami³, Pedram Fatehi³, Ahmed I A Soliman^{3

4}

Affiliations

¹ Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
² Chemistry Department, Faculty of Science, New Valley University, El-Kharja 72511, Egypt.
³ Chemical Engineering Department, Lakehead University, Thunder Bay, ON P7B5E1, Canada.
⁴ Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.

Abstract

In the present study, a new series of different heterocycles was synthesized through base-free Knoevenagel condensation of various aldehydes and active methylene-containing compounds using the hydrothermal developed Ag@TiO₂ as a heterogeneous catalyst. The catalyst was synthesized by mixing TiO₂ (P25) with AgNO₃ and hydrothermally treated in ethanol at 180 °C for 12 h. The developed Ag@TiO₂ catalyst was directly applied for Knoevenagel condensation, and the optimized procedure involved stirring the aldehydes and active methylene-containing compounds with Ag@TiO₂ in ethanol at 65 °C. The reaction scope was investigated for various aromatic and heterocyclic aldehydes with active methylene-containing compounds, and the isolated yields were significantly high. The reusability of the catalyst was investigated for up to five cycles, where an insignificant decrease in the catalyst's reactivity was observed. Also, the reaction could proceed in water as a solvent, and the isolated yield was 40%. Hence, this protocol features mild reaction conditions, a facile procedure, and clean reaction profiles.