A novel nanocatalyst praseodymium oxide (Pr₆O₁₁) for the efficient and sustainable synthesis of chromene derivatives <i>via</i> ultrasound irradiation in an aqueous hydrotropic medium

The development of sustainable and efficient catalytic methods for organic synthesis is a key focus in green chemistry. In this study, we report for the first time the novel application of praseodymium oxide (Pr₆O₁₁) as a nanocatalyst for the eco-friendly synthesis of 2-amino-3-cyano-7-hydroxy-4<i>H</i>-chromenes. The hydrothermal synthesis of praseodymium oxide (Pr₆O₁₁) nanoparticles was performed, and their structural studies were conducted using FTIR, XRD, TGA-DTA, SEM, EDX, BET, and TEM analysis. The Pr₆O₁₁ NPs were used as a nanocatalyst in the synthesis of 2-amino-3-cyano-7-hydroxy-4<i>H</i>-chromenes. The reactions were conducted under ultrasound irradiation in an aqueous hydrotropic medium, eliminating the need for hazardous organic solvents. The unique catalytic properties of Pr₆O₁₁ facilitated high yields of chromene derivatives, with excellent selectivity within short reaction times. The synergistic effect of ultrasound irradiation and hydrotropy enhanced the reaction kinetics, leading to improved efficiency and sustainability. The catalyst exhibited remarkable reusability and stability, maintaining its activity over multiple cycles without any significant loss in efficiency. This novel approach highlights the potential of Pr₆O₁₁ as a green and reusable nanocatalyst, offering a sustainable alternative for the synthesis of valuable heterocyclic compounds in aqueous hydrotropic media. The significant features of this method are the shorter reaction time, high product yield and use of a non-toxic, reusable, inexpensive, and biodegradable catalyst.