Investigation of the Effect of Alkyl Chain Length on Molecular Interactions Between Methyl Benzoate with Alcohols: A Study of Physicochemical Properties

Densities, speeds of sound, and viscosities of binary mixtures of methyl benzoate (MB) with ethanol, 1-propanol, and 1-butanol were measured at temperature ranging from T  = 293.2 to 313.2 K and refractive indices were determined at T  = 303.2 K. Excess molar volumes, V E , isentropic compressibility deviations ∆ κ s and viscosity deviations, Δ η , were obtained and fitted with the Redlich–Kister equation with satisfactory results. Based on the measured and derived physicochemical properties, the influence of the alkyl chain length of the alcohol on the molecular interactions of the studied mixtures was explored. The results show that both hydrogen bond interaction between carbonyl group of MB and hydroxyl group of alcohol and the packing efficiency, such as accommodation of alcohol in the interstice of MB, play an important role in the microstructure of the mixtures, which leads to the disruption of alcohol with the addition of MB. Moreover, by comparing V E , ∆ κ s and Δ η values of MB (1) + alcohol (2) systems at T  = 303.2 K, it is found that the strength of hydrogen bond interaction and the packing efficiency significantly weakens with increasing alkyl chain length of alcohol in going from ethanol to 1-butanol, resulting in the V E values of the studied systems gradually changing from a negative deviation to an S shape, the ∆ κ s and Δ η values have negative deviations, and the ∆ n D values have positive deviations. The obtained results will provide thermodynamic guidance for the industrial purification of methyl benzoate.