Solubility and solution thermodynamics of 4-hydroxybenzaldehyde in twelve organic solvents from T = (278.15 to 318.15) K

Abstract

In this study, the solid-liquid equilibrium of 4-hydroxybenzaldehyde in twelve solvents including methanol, ethanol, n-propanol, 1-butanol, isopropanol, ethyl acetate, 2-butanone, acetonitrile, toluene, N,N-dimethylformamide, 1,4-dioxane and acetone were constructed by the isothermal dissolution equilibrium method at a temperature range from (278.15 to 318.15)K under atmospheric pressure (101.2kPa), and the solubility values of 4-hydroxybenzaldehyde in these solvents were determined by a high-performance liquid chromatography. The mole fraction solubility increased with increasing temperature and obeyed the following order from high to low in different solvents except for 1,4-dioxane: N,N-dimethylformamide>2-butanone>acetone>ethyl acetate>(1-butanol, isopropanol)>n-propanol>ethanol>methanol>acetonitrile>toluene. The modified Apelblat equation, λh equation, Wilson model and NRTL model were used to correlate the solubility of 4-hydroxybenzaldehyde in different solvents. Results showed that the largest values of relative average deviation and root-mean-square deviation obtained with the four models were 2.66% and 78.9×10−3, respectively. Moreover, the mixing properties including the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy were calculated. The solution process of 4-hydroxybenzaldehyde was spontaneous and favorable in the selected solvents. The solubility data and thermodynamic studies would be invoked as fundamental data and models regarding purification process of 4-hydroxybenzaldehyde and optimization conditions for its bromination process.