Solid-liquid equilibrium, molecular simulation and thermodynamic properties of sulfaguanidine in pure and binary solvents from 288.15 K to 343.15 K

Abstract

The solubility of sulfaguanidine(SG) in water, methanol, ethanol, n-propanol, isopropanol, n-butanol and binary solvent systems (water + methanol/n-propanol) was determined by the synthetic method at local pressure values in the temperature range of 288.15 K to 343.15 K. The experimental data were compiled and plotted, and it can be seen that the solubility of SG in the six pure solvents and two binary solvent systems in the selected temperature range increased monotonically with increasing temperature. The solubility of SG in pure solvents was in the order of methanol > ethanol > n-propanol ≈ isopropanol > n-butanol > water. The solubility of SG in the mixture of water + methanol increased with the composition of the benign solvent, while the solubility in the mixture of n-propanol + water increased first and then decreased with the increase of the benign solvent. In addition, the Van’t Hoff model, Apelblat model, λh model and Wilson model were cited to correlate the solubility data of SG in pure and binary solvents, and additionally the binary models Apelblat-Jouyban-Acre (A-JA) model and Van't Hoff-Jouyban-Acre model were used to fit the solubility of SG in two binary solvents. The RAD and RMSD values show that the chosen models both show good correlation. The solvent effect was analyzed using the KAT-LSER model and the solubility of SG in the solvents used was mainly influenced by non-polarity and viscosity. After that, the inter-molecular forces of SG were explored using Hirshfeld surface analysis and a two-dimensional fingerprint was plotted. Finally, the thermodynamic properties of SG in all solvent systems, including Gibbs free energy, entropy and enthalpy, were calculated using Van’t Hoff equation and the experimentally measured solubility data.