Influence of electron-donating and electron-withdrawing substituents on thermo physical behaviour of3-dimethylamino-1-propylamine + propiophenone derivatives

This research presents a comprehensive investigation upon thermophysical and physicochemical properties of binary liquid mixtures of 3-dimethylamino-1-propylamine (DMAPA) and three para-substituted propiophenones (4-methylpropiophenone, 4-methoxypropiophe-none and 4-chloropropiophenone). Measurements of density, viscosity and ultrasonic speed were conducted across the entire composition range at various temperatures under atmospheric pressure. The results show negative values for VE and κsE, and positive values for ∆η and ∆G*E, suggesting strong intermolecular interactions between the amino groups of DMAPA and the carbonyl groups of ketones. Partial molar properties and molar volumes were derived to elucidate solute–solvent environment and packing efficiency within mixtures. The influence of para-substituents on the magnitude of these interactions showed distinct electronic effects on the mixture’s volumetric behaviour. Experimental findings were validated using Jouyban–Acree model, which demonstrated excellent agreement with low deviations. These findings provide critical thermodynamic insights into structural effects of substituted aromatic ketones in amine-based systems, offering valuable data for applications involving chemical processing and solvent design.