A Determination of the Hansen Solubility Parameters of Hexanitrostilbene (HNS)

The temperature-dependent solubility of hexanitrostilbene (HNS) [CAS# 20062-22-0] was determined in ten solvents and solvent blends using the Tyndall effect. Thermodynamic modeling of the data yielded Flory interaction parameters, the molar enthalpy of mixing, the molar entropy of mixing, and the molar Gibbs energy of mixing, All solutions exhibited endothermic enthalpies and positive entropies of mixing. The presence of water in some of the solvent blends made dissolution increasingly endothermic and disfavored solubility. The solubilities of HNS at 25 degrees C were used to determine the three-component Hansen solubility parameters (HSP) (delta(D) = 18.6, delta(P) = 13.5 delta(H) = 6.1 MPa1/2) and the radius of the solubility sphere (R-0 = 5.8 MPa1/2). The HSP determined for HNS using group-additivity (delta(D) = 2 1.0, delta(P) = 13.3, and delta(H) = 8.6 MPa1/2) also correctly predicted the optimum solvents for this explosive.