Thermodynamic and electrochemical evaluation of superbase‐derived ionic liquids: Structure and temperature effects

Understanding the structure–property correlations of ionic liquids, particularly their physicochemical characteristics and corrosion‐inhibiting mechanisms, is critical for enabling their scalable deployment in green chemical engineering. This study systematically investigates six superbase‐derived ionic liquids (SILs) to establish structure–property relationships by varying cation ring size ([DBUH] + vs. [DBNH] + ) and anion alkyl chain length/functionalization. The anion elongation and electron‐donating groups of SILs reduce density/surface tension but increase viscosity and decrease conductivity, primarily due to strengthened hydrogen‐bonding and enhanced van der Waals forces. The derived Hildebrand solubility parameter successfully predicts superior lignin solubility (up to 15.3%) in [DBUH][CH 3 CH 2 OCH 2 COO]. Electrochemical analyses demonstrate that [DBUH][CH 3 CH 2 OCH 2 COO] with longer anion chains and electron‐donating groups exhibit significantly lower corrosivity toward 304 stainless steel and Q235 carbon steel, attributed to their higher viscosity stabilizing protective passive layers. This work provides a rational molecular design framework for developing low‐corrosion, high‐performance SIL solvents for biomass processing.