Solubility, Hansen solubility parameter, molecular simulation and thermodynamic analysis of N-methyl-3,4,5-trinitropyrazole at various temperatures

Abstract

• The solubility data of MTNP was measured by a laser monitoring method. • The experimental values were correlated and calculated by four equations. • Solubility order was analysed by using the Hansen solubility parameter. • The E inter was calculated by molecular simulation based on DFT for explaining the solubility order. • The thermodynamic parameters were calculated by the van’t Hoff and Gibbs equations. The solubility of N-methyl-3,4,5-trinitropyrazole (MTNP) in (isopropanol + ethanol) mixtures at T = 283.15 K-323.15 K was tested by a laser monitoring method. The solubility of MTNP increases with the increasing temperature in (isopropanol + ethanol) mixtures. The solubility of MTNP decreases with the increasing isopropanol mass fraction ranging from 0.10 to 0.90. Besides, supersolubility (the metastable zone width) of MTNP was determined by a laser monitoring method. The experimental results showed that the solubility of MTNP in (isopropanol + ethanol) solvent mixtures increases with increasing temperature and the metastable zone width decreases with increasing temperature. Additionally, the values were correlated by the modified Apelblat equation, van’t Hoff equation, CNIBS/R-K model and Ma model. In addition, Hansen solubility parameters were used to explain the solubility order. Solubility order of MTNP in (isopropanol + ethanol) solvent mixtures was interpreted by comparing the interaction energy ( E inter ) between MTNP and binary solvent. The apparent thermodynamic properties of Gibbs energy, enthalpy and entropy were calculated by the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for MTNP was discussed. Finally, solid-liquid surface tension and surface entropy factor were obtained by the solubility data.