Solubility and thermodynamics of ferulic acid in different neat solvents: Measurement, correlation and molecular interactions

Abstract

In the present investigation, the solubility of a bioactive compound ferulic acid (FA) in various neat solvents namely “water, methanol, ethanol, isopropanol (IPA), ethylene glycol (EG), propylene glycol (PG), 1-butanol, 2-butanol, ethyl acetate (EA), dimethyl sulfoxide (DMSO), polyethylene glycol-400 (PEG-400) and Transcutol®” was measured, correlated and evaluated for molecular interactions. The solubilities of FA in mole fraction were measured at temperatures “T = 298.2 K to 318.2 K” and pressure “p = 0.1 MPa”. The experimental solubilities of FA were correlated with “Van't Hoff and Apelblat models” with root mean square deviation values of < 2.0%. The solubilities of FA in mole fraction were recorded maximum in PEG-400 (1.91 × 10− 1) followed by DMSO (6.47 × 10− 2), Transcutol (5.92 × 10− 2), PG (3.59 × 10− 2), methanol (3.15 × 10− 2), ethanol (3.08 × 10− 2), EG (2.71 × 10− 3), IPA (2.55 × 10− 2), 2-butanol (2.47 × 10− 2), 1-butanol (2.38 × 10− 2), EA (1.98 × 10− 2) and water (1.36 × 10− 4) at “T = 318.2 K” and similar trend was also obtained at each temperature level. Generally, FA showed good solubilization potential in each neat solvent except in water. The activity coefficients of FA in each neat solvent were also determined in order to evaluate the molecular interactions between FA and solvent molecules. Higher solute-solvent interactions were seen in “PEG-400, DMSO and Transcutol” based on activity coefficients results. “Apparent thermodynamic analysis” showed an “endothermic and entropy-driven dissolution” of FA in each neat solvent.