DES Ecoscale: A Quantitative Sustainability Assessment Framework for Deep Eutectic Solvents

High Resolution Image Download MS PowerPoint Slide Deep eutectic solvents (DESs) are widely proposed as sustainable alternatives to conventional solvents, yet their environmental performance is often inferred from qualitative arguments or process-focused metrics that fail to capture solvent-specific hazards and lifecycle effects. Herein, we introduce the DES Ecoscale, a quantitative 100-point sustainability assessment framework specifically developed for deep eutectic solvents and aligned with safe-and-sustainable-by-design (SSbD) principles. The framework integrates five lifecycle-relevant dimensions: component sustainability, synthesis conditions, physicochemical properties and performance, application-phase considerations, and end-of-life behavior, with application-specific variants enabling context-aware evaluation. Validation across 15 representative DES and NADES systems yields scores ranging from 66 to 98 points, clearly discriminating between sustainable and problematic formulations. Natural deep eutectic solvents composed of GRAS-approved components consistently achieve excellent sustainability ratings, while synthetic systems score significantly lower. Statistical analysis confirms framework robustness: NADES systems outperform synthetic DESs (96.5 ± 1.3 vs 78.5 ± 8.9 points, p < 0.001), and component sustainability and physicochemical properties together explain 84% of the variance in total scores. Comparison with established green chemistry metrics demonstrates that conventional tools fail to distinguish DES sustainability when hazards arise from component identity rather than synthesis efficiency, as illustrated by a 24-point difference between choline chloride/urea and choline chloride/phenol resolved only by the DES Ecoscale. Implemented as an operational computational tool, the DES Ecoscale represents a validated first-generation screening framework enabling rapid, transparent, and reproducible sustainability screening for Type III and Type V DES systems, providing actionable guidance for solvent design, selection, and optimization across research, industrial, and regulatory contexts.