Thermodynamic and Transport Excess Properties of Ethyl Benzoate + 2-Methyl-2-Propanol Binary Mixtures At (303.15–318.15) K

Abstract : Excess thermodynamic and transport properties of binary liquid mixtures composed of ethyl benzoate (X₁) and 2-methyl-2-propanol (X₂) were measured over the entire composition range at four temperatures: 303.15, 308.15, 313.15, and 318.15 K at atmospheric pressure. Experimental properties including excess molar volume (Vᵉ), excess isentropic compressibility (Δβₐd), viscosity deviations (Δη), excess free length (Lᵉ), excess surface tension (πᵉ), excess acoustic impedance (Zᵉ), excess enthalpy (Hᵉ), excess Gibbs free energy (Gᵉ), and ultrasonic velocity (U) were systematically evaluated. The results indicate consistently negative Vᵉ, Δβₐd, and Δη values across all compositions and temperatures, with magnitudes that reach minima near equimolar composition, suggesting strong specific interactions between unlike molecules, especially dipole–dipole and hydrogen bonding effects. Temperature rise generally reduces the magnitude of excess properties, indicative of diminished molecular interactions and structural organization at elevated thermal energy. All excess functions were correlated using the Redlich–Kister polynomial equation, demonstrating excellent fit quality and enabling estimation of binary interaction parameters. The observed trends in excess enthalpy and Gibbs free energy reveal significant non-ideal behavior, likely due to disruption of self-association in 2-methyl-2-propanol clusters upon mixing with aromatic ester molecules. Comparisons with literature reveal qualitative agreement with related binary systems involving esters and alcohols, confirming the reliability of the measured data. Overall, this study provides comprehensive thermodynamic insights into molecular interactions in ester-alcohol mixtures, supporting improved modeling of solution behavior relevant to industrial and formulation applications.