LAUSR

Abstract The solvation behavior of 1,1,3,3 tetramethylguanidinium [TMG] ionic liquids (ILs) containing different carboxylate anions, octanoate (C8H15O2)-, decanoate (C10H19O2)- and laurate (C12H23O2)-, in dimethylsulfoxide (DMSO) and dimethylformamide (DMF) are examined through apparent molar properties. In this work, three ILs were chosen as they are protic and interact with polar solvents, affecting the thermophysical properties. We have measured the thermophysical properties to study the interactions between ion-ion and ion-solvent and analyzed the influence of IL anion and temperature through the experimental measurements of density and speed of sound. The measurement was carried out as a function of molality (0.05 to 1.0 mol∙kg-1) and temperature from 293.15 to 328.15 K under atmospheric pressure. The binary systems contained the ILs [TMGH]+[C8H15O2]-, [TMGH]+[C10H19O2]- and [TMGH]+[C12H23O2]-. The apparent molar volume (Vϕ) and the apparent molar isentropic compressibility ( K s , ∅ ) were calculated using the experimental data and a Redlich-Mayer type equation was fitted to calculate the limiting parameters ( V ∅ ∞ and K s , ∅ ∞ ) to understand the vital empirical parameters of the studied ILs. The effect of carbon chain length on apparent molar volume (Vϕ) and the apparent molar isentropic compressibility ( K s , ∅ ) with concentration and temperature range was studied.