Thermodynamic study of mesitylene plus alkanol mixtures: Insights into molecular interactions

초록

Excess properties are a powerful tool for understanding the intermolecular interactions in mixtures. In this study, the excess molar volume (VEm), excess isentropic compressibility (& kappa;Es) deviation in ultrasonic speed (& UDelta;u), and refractive index (& UDelta;nD) were analyzed for mixtures of mesitylene and alkanol to interpret their intermolecular interactions. Our findings demonstrate that positive values of VEm and & kappa;Es indicate the predominance of the rupture of H-bonding in self-associated alkanol dominate over the electron donor-acceptor interaction between the hydroxyl group of alkanol and & pi;-electrons of mesitylene. It was also observed that these electron donor-acceptor interactions weaken as the temperature increases. These observations were further supported by the behavior of molecular association parameter (MA), free intermolecular length, and available volume. Among the alkanols studied, n-butanol exhibited the highest value of MA, suggesting a strong degree of molecular association due to favorable intermolecular interactions between the dissimilar molecules. In contrast, sec-butanol showed the lowest value, which can be attributed to the steric hindrance caused by three methyl groups of mesitylene and the two methyl groups attached to a hydroxyl carbon atom in sec-butanol. Regarding correlation, Schaffs collision factor theory demonstrated high predictive power for ultrasonic speed compared to other models.

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