Effect of alkyl chain length and temperature on volumetric, acoustic and apparent molar properties of pyrrolidinium based ionic liquids in acetonitrile

Detailed analysis of volumetric and acoustic properties of the dilute solution of ionic liquids (ILs) and acetonitrile play a significant role in the potential engineering field and process design. Moreover, these studies can provide relevant knowledge about the types and scope of the intermolecular interactions governed between the solute and solvent. In this work, three iodide based pyrolidium ILs, i.e. 1-butyl-1-methyl pyrrolidinium iodide, [BMPY]I and 1-methyl-1-pentyl pyrrolidinium iodide, [PeMPY]I and 1-hexyl-1-methyl pyrrolidinium iodide, [HMPY]I were synthesized and studied their density and sound velocity in acetonitrile as a function of molality in the range of 0.05–0.4 mol·kg−1 and temperature in the range from 293.15 to 328.15 K at atmospheric pressure. The impact of chain length of cation and temperature were premeditated by using well-known volumetric and acoustic factors. In addition, by employing the experimental data, the apparent molar volume (Vϕ), apparent molar isentropic compression (Ks,ϕ), and limiting apparent molar expansion (Eφ∞) were calculated. Further, the apparent molar properties at infinite dilution were examined by using Redlich-Mayer type equations. Furthermore, measured and calculated properties have been analysed to understand the solute-solvent interaction in studied systems. For the studied systems, infinite dilution apparent molar properties were increased with cationic chain length on the ILs, however, decreased with temperature.