Solvent free green synthesis of tri-substituted imidazoles catalyzed by multi-doped ZnO-GCN nanocomposites

Abstract

Applying the method of grinding, a series of 2,4,5-tri-substituted imidazole derivatives have been synthesised in highly satisfactory yields without the need for a solvent. In which grinding a mixture of benzoin or benzil and verities of the aldehydes in the existence of ammonium acetate, as a nitrogen source is successfully synthesized by using the efficient multi-doped ZnO- graphitic carbon nitride (g-C3N4) nanocomposite catalyst (Bi (4 %), Cr(1 %)-doped ZnO-GCN). In this protocol, comparative studies of the single-pot synthesis of 2,4,5-trisubstituted imidazole compounds are performed by using conventional and mechanochemical grinding methods with and without Bi-Cr-doped ZnO-GCN nanocomposite catalyst. All synthesised compoundswere characterised by their melting points, 1HNMR, and 13CMR spectra. In these studies, we found that grinding methodology with Bi-Cr-doped ZnO-GCN nanocomposite catalyst enhanced the reaction efficiencies with a short reaction time, excellent products, a cleaner reaction, and an easy workup. Additionally, the reaction follows green chemistry guidelines because it just requires the grinding of the substrates and catalyst in the absence of a solvent. Furthermore, the final product is simply purified by recrystallization as well as whenever needed using the column chromatography process.