Liquid Densities and Excess Quantities for the Green Esterification Process

Liquid densities of deep eutectic solvents (DESs) such as choline chloride + glycerol {[ChCl]­[Gly]}, choline chloride + acetic acid {[ChCl]­[AA]}; ionic liquids (ILs), such as 1-ethyl-3-methylimidazolium hydrogen sulfate {[EMIM]­[HSO₄]}, 1-ethyl-3-methylimidazolium ethyl sulfate {[EMIM]­[EtSO₄]}, and 1-butyl-3-methylimidazolium acetate {[BMIM]­[Ac]}; and mixture of DESs + ILs as well as organic mixtures, such as n-butyl acetate + butanol and n-butyl acetate + acetic acid were measured at different temperatures from 293.15 to 343.15 K with an increase of 5 K. From this measured density, isobaric expansivity, excess molar volume, partial molar volume, excess partial molar volume, and apparent molar volume were calculated to understand and characterize the solution behavior as well as solvent–solvent interactions for the entire mole fraction at different temperatures. The excess molar properties showing positive deviation for DESs + ILs system, which indicates a creation of volume in the binary mixtures and disruption of H-bonds in the solution environment. Further, the sign and magnitude of all of the studied binary systems gave a good estimate of the attractive and disruptive interactions, chemical aggregation, H-bond formation, salt (choline chloride)–H (imidazolium) interaction, and salt (choline chloride)–O (acetate anion) interaction between those two components in the binary mixtures. The Redlich–Kister equation was used to fit the excess molar volume data and their corresponding regression coefficients (R²) were also found. The σ-profile and σ-potential for the compounds in the present study have been generated and analyzed by means of specific molecular interactions between all of the studied compounds using the conductor like screening model for real solvents model.