Research on dissolution behavior of N-hydroxyphthalimide in three binary solvents: Measurement, modeling, molecular simulation and thermodynamics

Abstract

Solubility data, relevant thermodynamic parameters as well as molecular interactions of N-hydroxyphthalimide (NHPI) in three binary solvents of (2-methoxyethanol (EGME), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone(NMP)) + water were focus of this research work. Experimental solubility values of NHPI in selected solvents ranged from 278.15 K to 323.15 K were obtained by laser monitoring method at 0.1 MPa. Corresponding results suggested that NHPI solubility increased with ascending temperature and increasing mass fraction of positive solvents (EGME, DMF, NMP) of binary solvents. The maximum solubility data of NHPI was found in neat DMF at 323.15 K while the minimum solubility data was obtained in pure water at 278.15 K. For investigation of solubility behavior, molecular electrostatic potential surface (MEPS), solvation free energy as well as radial distribution function (RDF) were performed by Multiwfn program and Material Studio (MS) 2017 software. Results indicated that solute–solvent interaction and solvent–solvent interaction played an important role in solubility behavior. Moreover, solubility modeling was realized by Wilson model, λh equation and modified Apelblat equation, three models acquired acceptable results with average relative deviation (ARD) less than 6.601 % and root mean square deviation (RMSD) no more than 1.461 ‰. Furthermore, thermodynamic parameters of dissolution process including enthalpy, entropy and Gibbs free energy were also discussed in this research work. The dissolution process was always endothermic and entropically driven.