Investigation on molecular interaction of glycols in methanol solutions of methylparaben (methyl 4 – hydroxybenzoate) at different temperatures through thermo-acoustical analysis

Abstract

To determine the nature of interaction of ethylene glycol (EG), propylene glycol (PG), and hexylene glycol (HG) in the methanol solutions of methylparaben, density and speed of the sound of ethylene glycol, propylene glycol, and hexylene glycol in methylparaben–methanol (MePB–MeOH) solutions were investigated at different temperatures (from 293.15 to 308.15 K) and at the pressure, p = 0.1 MPa. The computed density and speed of sound values were utilized to determine the apparent molar volume and apparent molar isentropic compressibility of glycols in the binary solvent. The apparent molar volume Vϕ0 and apparent molar isentropic compressibility Kϕ, s0 at infinite dilution for all the ternary system were computed at all working temperatures. The limiting partial molar volume Vϕ0 increases with temperature and indicates that the solute–solvent interaction for HG in methanol solutions of MePB are stronger than EG and PG in methanol solutions of MePB. The positive values of apparent molar expansibility at infinite dilution, signify the existence of solute–solvent interaction in the inspected system. The isentropic compressibility, βs for the present studied system, increases with increase in temperature. The negative Kϕ, s0 values, for the investigated ternary systems, can be attributed to the predominance of penetration effect over solvent intrinsic compressibility.