Magnetic horsetail plant ash (Fe3O4@HA): a novel, natural and highly efficient heterogeneous nanocatalyst for the green synthesis of 2,4,5-trisubstituted imidazoles

Horsetail plant ash (HA), as a natural source of mesoporous silica, has been prepared from the exposure of horsetail plant (Equisetum Arvense) to high temperature. In the present study, a new magnetically separable and also recoverable Fe3O4 nanoparticles were synthesized in the presence of natural horsetail plant ash (HA) as a support to result in Fe3O4@HA. FT-IR, XRD, TEM, SEM-EDX and VSM analysis were combined to characterize the morphology and structure of this novel synthesized nanocatalyst. This magnetically solid acid nanocatalyst showed an excellent catalytic activity for the synthesis of 2,4,5-trisubstituted imidazoles at room temperature in aqueous media. The procedure led to corresponding products in high to excellent yields and appropriate times. Additionally, this nanocatalyst can be easily recovered by a magnetic field and reused for six other consecutive reaction runs without noticeable loss of its catalytic efficiency. Based on this study, Fe3O4@HA is found to be an efficient, magnetically separable, recyclable, and green catalyst with natural source. Graphic abstract In this work, horsetail plant ash was used as a natural source of mesoporous silica for the synthesis of Fe3O4@HA as a highly powerful magnetically solid acid nanocatalyst, which was fully characterized using various techniques. The activity of the newly synthesized nanocatalyst was tested for the synthesis of 2,4,5-trisubstituted imidazole derivatives.

Automated summary

In this study, horsetail plant ash was used as a natural source of mesoporous silica for the synthesis of Fe3O4@HA as a highly powerful magnetically solid acid nanocatalyst, which showed excellent catalytic performance for the synthesis of 2,4,5-trisubstituted imidazoles in aqueous media at room temperature. The nanocatalyst can be easily recovered by a magnetic field and reused for multiple reaction runs.