Study on the dissolution behaviors of CL-20/TNT co-crystal in N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO)

Abstract

2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)/2,4,6-trinitrotoluene (TNT) co-crystal in 1:1 molar ratio was prepared by a solvent evaporation method, and the structural characterizations of CL-20/TNT co-crystal were systematically investigated by powder X-ray diffraction, Raman and differential scanning calorimeter. The dissolution behaviors of CL-20/TNT co-crystal in N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were investigated by a DC08-1 Calvet microcalorimeter at 298.15 K, showing that the dissolution processes were all exothermic. The heat effects (Q) of CL-20/TNT co-crystal dissolved in DMF and DMSO both increased with the increase of the amount of co-crystal. Empirical formulas for the calculation of the enthalpies of dissolution ($\Delta _{\text{diss}} H$), relative apparent molar enthalpies ($\Delta _{\text{diss}} H_{\text{apparent}}$), relative partial molar enthalpies ($\Delta _{\text{diss}} H_{\text{partial}}$) were obtained from the experimental data of CL-20/TNT co-crystal dissolved in DMF and DMSO. It was found that the values of $\Delta _{\text{diss}} H$, $\Delta _{\text{diss}} H_{\text{apparent}}$ and $\Delta _{\text{diss}} H_{\text{partial}}$ were affected by the molality of co-crystal (b). The kinetic equations describing the dissolution of CL-20/TNT co-crystal in DMF and DMSO at 298.15 K are ${\text{d}}\alpha / {\text{d}}t = 10^{ - 2.39} \left( {1 - \alpha } \right)^{0.89}$ and ${\text{d}}\alpha / {\text{d}}t = 10^{ - 2.47} \left( {1 - \alpha } \right)^{0.62}$, respectively.