Easy single-step preparation of ZnO nano-particles by sedimentation method and studying their catalytic performance in the synthesis of 2-aminothiophenes via Gewald reaction

Zinc oxide is a multi-purpose active material with important catalytic applications. In this study, nano-sized ZnO particles were easily synthesized through sedimentation of zinc acetate di-hydrate in absolute ethanol and were characterized by XRD and SEM. The XRD results indicated pure wurtzite structure with the average particle size of 26.9 nm for the nano-particles. It was observed that size of ZnO nano-particles was decreased while solution concentration was increased. This observation would be explained considering enhancing nucleation processes of nano-particles at high concentration of zinc acetate. The prepared nano-particles (2.5 mol%) were used as catalyst for the fast and efficient synthesis of 2-aminothiophenes under solvent free conditions. The three-component mixture of a carbonyl compound, malonodinitrile, and elemental sulfur was converted into the corresponding 2-aminothiophene in moderate to high yields with excellent selectivity.

Graphical abstractThe nano-sized ZnO particles were easily synthesized through sedimentation of zinc acetate di-hydrate in absolute ethanol and were characterized by XRD and SEM. The prepared nano-particles (2.5 mol%) were used as catalyst for the fast and efficient synthesis of 2-aminothiophenes under solvent free conditions.Figure optionsDownload full-size imageDownload high-quality image (181 K)Download as PowerPoint slideHighlights► Easy preparation of nano-sized ZnO by sedimentation method. ► New and efficient method for the synthesis of 2-aminothiophenes. ► A highly reusable heterogeneous catalyst.