Investigation of Intermolecular Interactions in α‐Terpineol‐Cresols Mixtures: A Multidimensional Approach Using Thermophysical, Acoustic, Spectral, and Quantum Analyses

ABSTRACT This study explores the densities and speed of sound of binary mixtures of α‐terpineol with o ‐, m ‐, and p ‐cresol at 303.15, 308.15, and 313.15 K under atmospheric pressure. Using these measurements, properties such as molar volume ( V m ), excess molar volume , partial and apparent molar volumes , deviations in speed of sound (Δ u ), isentropic compressibility (Δκ s ), acoustical impedance (Δ z ), and intermolecular free length ( L f ) were calculated. Additionally, infinite dilution values, Redlich–Rosenberg–Mayer parameters ( S v , B v and S k , B k ) and limiting apparent molar expansibility were determined. Theoretical sound velocities and standard deviations were computed and excess/deviation properties were correlated using Redlich–Kister polynomials. FT‐IR spectra of selected binary mixtures (4:1, 1:1, 1:4) at 298.15 K were analyzed to probe molecular interactions. Density functional theory (DFT)‐based computational studies of optimized structures of pure and mixed systems were conducted to evaluate bond lengths, Mulliken charges, vibrational frequencies, and NBO analysis. Results provide insight into the nature, strength, and variation of intermolecular interactions with respect to temperature and composition.