An experimental-computational analysis of molecular interactions and its effect on thermodynamic properties of mixtures of isobutanol and ethylbenzene

In order to comprehensively examine the structure and interactions within the system of isobutanol and ethylbenzene, as well as their binary mixture, both experimental and computational studies were conducted. In the experimental part, the densities , ρ , of these substances and various mole fractions of their mixture were measured at temperatures ranging from 293.15 K to 313.15 K and at an absolute pressure of 86.7 kPa. Based on the obtained density data, thermodynamic properties such as excess molar volumes , V m E , thermal expansion coefficients , α , excess thermal expansion coefficient , α E , and isothermal coefficient of excess molar enthalpy , ∂ H m E / ∂ P T , x i ,were determined. The Redlich-Kister polynomial equation was used to fit the data. The interactions between both components and their mixtures were analyzed and the system's non-ideal behavior was discussed. In the computational section, Density Functional Theory (DFT) calculations were performed to determine the optimized structures and hydrogen bond interactions in isobutanol, as well as the effect of ethylbenzene on isobutanol. Additionally, Frontier Molecular Orbital (FMO) analysis, molecular electrostatic potential (MEP) surface plots, and the Atoms in Molecules (AIM) approach were employed. Finally, molecular dynamics (MD) simulations were carried out, and the results were used to calculate densities and radial distribution functions (RDFs) at 298.15 K and 1 atm. These functions provided valuable insights into the interactions within the system. At the end, the results obtained from the combination of experimental and computational methods are presented.