Study of solvation of substituted propylbenzene in ethanol-water solutions under subcritical conditions by molecular dynamics

Abstract

Solutions of 2-methoxy-4-(2′-hydroxypropyl)phenol (PrPh) in water and water-ethanol mixtures (0.020, 0.115, 0.285 mol fraction of ethanol) at temperature 573 K and densities corresponding to an experimental pressure of 23 MPa have been simulated by molecular dynamics. Distribution of components in the fluid bulk and in the PrPh solvate shell has been researched. Numbers and lifetimes of hydrogen bonds between the components have been determined, and tendencies to selective solvation have been analyzed. It has been shown that PrPh molecules form stable long-lived hydrogen bonds with water and ethanol. An increase in ethanol concentration leads to a decrease in the number of hydrogen bonds formed by PrPh and to an increase in their lifetime that indicates growing stability of the solvate complexes. The local mole fraction of ethanol around PrPh is lower than its average mole fraction in the fluid, i.e., the PrPh solvate shells mainly consist of water molecules.