Experimental and Theoretical Investigation on Imidazole Derivatives Using Magnetic Nanocatalyst: Green Synthesis, Characterization, and Mechanism Study

Abstract

The green synthesis of 4,5-diphenyl-1H-imidazole derivatives was studied experimentally and theoretically through a one-pot, three-component reaction of diverse aldehydes, ammonium acetate, and benzil using Fe₃O₄@C@PrNHSO₃H nanoparticles under solvent-free conditions. The core-shell magnetic nanoparticles of Fe₃O₄@C@PrNHSO₃H were introduced as an effective, environmentally friendly, and magnetically removable catalyst in the reaction. The recovered catalyst could be used eight times with admirable catalytic activity. Before entering the laboratory, the synthesis of imidazoles was studied from a computational point of view to find the most plausible mechanism and select the appropriate raw materials. Three probable mechanistic paths were considered. Density functional theory (DFT) calculations confirmed the following mechanism: (1) reaction of benzil and ammonia to form iminoethanone, (2) reaction of aldehyde and ammonia to form imin, (3) reaction of imin with iminoethanone and ring formation, and (4) rearrangement to produce 4,5-triphenyl-1H-imidazole. The results were affirmed by the frontier molecular orbitals, natural bond orbital analyses, and molecular electrostatic potential calculations.

HIGHLIGHTS

• The green synthesis of 4,5-diphenyl-1H-imidazole derivatives was studied experimentally and theoretically using Fe₃O₄@C@PrNHSO₃H nanoparticles (NPs).

• Three proposal mechanisms were considered using M062X/6-311++G(d,p) to achieve the most plausible mechanism,

• The proposed mechanism was verified by the frontier molecular orbitals, natural bond orbital analyses, and molecular electrostatic potential calculations.

• The Fe₃O₄@C@PrNHSO₃H NPs were introduced as an effective, eco-friendly and magnetically recoverable catalyst in the one-step synthesis of imidazoles.

• The recovered catalyst could be used eight times with admirable catalytic activity.

Graphical Abstract

Keywords:

• Green synthesis
• Theoretical study
• Imidazole derivatives
• Fe3O4@C@PrNHSO3H NPs

Disclosure statement

No potential conflict of interest was reported by the author(s).