Effect of position of OH group in isomeric butanediols on intermolecular interaction with Choline Acetate: A thermodynamic study at different temperatures

Abstract

The prominent effect of the position of hydroxyl groups in isomeric butanediols i.e.1,3-butanediol (1,3-BTD), 1,2-butanediol (1,2-BTD) and 2,3-butanediol (2,3-BTD) on intermolecular interactions with Choline Acetate has been investigated using various thermophysical parameters such as density ρ, speed of sound u, refractive index nD and specific conductivity κ over different concentration range and at temperatures varying from 293.15 to 323.15 K at atmospheric pressure. To gain further insight the derived parameters such as apparent molar volumes Vϕ, apparent molar isentropic compressibilities Ksϕ, and their infinite parameters mainly limiting apparent molar volumes at infinite dilution Vϕo, limiting apparent molar expansibilities Eϕo, limiting isentropic compression Kϕo, molar refraction Rm and infinite molar conductance ̂mo values have been calculated. The least values obtained for apparent molar volumes and compressibilities in case of 1,3-BTD mixtures are attributed to its highest ability to form intramolecular hydrogen bonding among isomeric butanediols and thus lesser availability to interact with Choline Acetate molecules. However for 2,3-BTD and 1,2-BTD binary mixtures the results have been explained on the basis of hydrophobic or iceberg effect where alkyl groups are present either on one end (1,2-BTD) or at both ends (2,3-BTD) while OH groups are located at vicinal carbon atoms.