Authors: Fatima Ibrahim Baiwa, Amina Ibrahim Baiwa
Abstract: The environmental and health hazards associated with conventional organic solvents have intensified the global shift toward sustainable chemical processes. This review critically examines the role of green solvents in modern organic synthesis, with emphasis on their physicochemical properties, reaction performance, environmental impact, and industrial applicability. A systematic review methodology was adopted, involving the analysis of peer-reviewed literature, industrial reports, and green chemistry databases. Studies were selected using defined inclusion criteria based on reaction efficiency, toxicity, recyclability, energy consumption, and economic feasibility. Comparative evaluation was performed across six major solvent classes: water, supercritical carbon dioxide, ionic liquids, deep eutectic solvents, bio-based solvents, and solvent-free systems. The analysis reveals that green solvents consistently demonstrate improved reaction yields (typically 85–99%), enhanced selectivity, reduced volatile organic compound emissions, and significantly lower energy requirements compared to traditional solvents. Water-mediated and solvent-free reactions showed the highest sustainability performance, while deep eutectic solvents and bio-based solvents emerged as the most promising scalable alternatives due to their low cost, biodegradability, and high recyclability. Industrial case studies further indicate substantial reductions in hazardous waste generation and regulatory burden following adoption of green solvent technologies. This review contributes a comprehensive comparative framework for evaluating green solvent performance and identifies key research gaps, including the need for standardized sustainability metrics and long-term toxicity assessment of emerging solvent systems. The findings reinforce the critical role of green solvents in advancing sustainable organic synthesis and highlight future opportunities in AI-assisted solvent design, switchable solvent systems, and circular solvent economies.
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