Nanomaterials functionalized acidic ionic organosilica as highly active catalyst in the selective synthesis of benzimidazole via dehydrogenative coupling of diamines and alcohols

Abstract

Abstract An acidic tungstate-based zwitterionic organosilica drived simple self-condensation of tungstic acid and zwitterionic organosilane (PMO-IL-WO4 2−), was remarkably demonstrated to be highly efficient and environmentally friendly catalyst for directly selective synthesis of benzimidazoles from benzyl alcohols under atmpshpheric air pressure and without any additional oxidant. The one-pot synthesis of benzimidazoles from benzyl alcohols and 1,2-phenylenediamine was efficiently achieved via direct dehydrogenative reaction using a low amount of recoverable PMO-IL-WO4 2− nanocatalyst in water under ambient conditions with a conversion efficiency of more than 90%. Enhancements in yield and selectivity of benzimidazole formation were observed when water was utilized as the solvent. Furthermore, the PMO-IL-WO4 2− nanocatalyst exhibited exceptional stability, demonstrating the ability to be effortlessly separated and reused for at least eight reaction cycles without any noticeable loss in activity or product selectivity. This method supports an eco-friendly atom economy and provides a sustainable approach to accessing benzimidazoles directly from benzyl alcohols under mild conditions, demonstrating its potential for practical applications in organic synthesis.

Keywords

• Tungstate-based nanocatalyst
• Benzimidazole
• Iionic liquid
• Organosilica
• Dehydrogenative coupling