Green Synthesis of Benzimidazole Derivatives Using Natural Deep Eutectic Solvents

Abstract

This article develops an evidence-based strategy for preparing benzimidazole derivatives in natural deep eutectic solvents (NADES). Recent peer- reviewed studies from 2023-2026 were critically combined with an author-designed protocol for the condensation o f o-phenylenediamine and aromatic aldehydes. The proposed media are not treated as passive solvent substitutes: their hydrogen - bond networks may activate the aldehyde, support proton transfer, promote ring closure, and influence aerobic aromatization. Betaine- and choline-based mixtures with lactic or malic acid are prioritized, while glycerol -based media serve as lower-acidity controls. The workflow integrates solvent characterization, water- content control, temperature screening, precipitation-based isolation, analytical confirmation, and solvent reuse. Performance is assessed through yield, selectivity, reaction mass efficiency, process mass intensity, E -factor, energy demand, and recovery. No unperformed experiment is presented as measured data; the result is a testable methodological framework for sustainable heterocyclic synthesis.