One pot, two-step synthesis of 2-(subs.)-1H-benzimidazoles using wet copper slag as magnetically separable and recyclable catalyst

Abstract

This work describes the first-ever use of Wet copper slag for 2-(subs.)-1H-benzimidazoles synthesis. It is a by-product of the copper refining and smelting processes utilized as a basic catalyst in the present work. Wet copper slag is prepared by immersing a natural copper slag in water to improve the hydroxyl group and, hence, basicity. Iron oxide content in the copper slag helps provide the basic environment and uses surrounding air for the successful oxidative condensation of imines and o-phenylenediamine. Various aldehydes reacted well with p-anisidine for imine synthesis. Further reaction with substituted o-phenylenediamine and o-phenylenediamine gives desired 2-(subs.)-1H-benzimidazoles in environmental-friendly ethanol: water (9:1) as solvent at 85 °C within 40 to 60 min. The present method showed critical advantages of mild reaction conditions, wide availability, recyclability, and magnetic separability of a Copper-slag with moderate to excellent product yields. Overall, the present approach offers a promising route for the efficient and sustainable synthesis of 2-(subs.)-1H-benzimidazoles, which have a wide range of applications in various fields, including pharmaceuticals, agrochemicals, and materials science.

Keywords

• Wet copper-slag
• Magnetically separable catalyst
• Sustainable catalyst
• Recyclable catalyst
• Reusable catalyst
• 2-(subs.)-1H-benzimidazoles