Experimental and theoretical study of solubility of 1,3,5-trinitrohexahydro-s-triazine (RDX) in alcohols.

摘要

The solubility of 1,3,5-trinitrohexahydro-s-triazine (RDX) in different alcohols were measured by HPLC, DSC, GC/MS, and NMR. The conformation of RDX in acetone-D6 solution was verified by vibrational studies using Raman spectroscopy. The thermodynamic parameters and conformations were calculated using density functional theory, Hartree-Fock, and the polarized continuum model.;Raman studies suggest that the RDX molecule has approximate C3v symmetry in solution, with alteration of the attached NO2 groups. The solubility of RDX in alcohols (ethyl alcohol, 2-methyl-1-propanol, 2-propanol and 1-butanol) has been determined at six different temperatures, 15, 20, 25, 30, 35, 40°C. From the solubility data, the values of thermodynamic functions such as Enthalpy (ΔsolvH), Entropy (Δ solvS) and free energies of solutions or solvation (Δsolv G) were obtained.;In the calculation, different basis sets for DFT and HF methods are reported for the geometry, energy, and Gibbs solvation energy of the high explosive in the gas phase and dissolved in alcohols, as previously mentioned. The Polarizable Continuum model (PCM) has been applied to investigate the effect of the alcohols medium on these AAA-RDX, AAE-RDX and EEE-RDX conformers. The inclusion of a solvent reaction field has a strong influence on the Gibbs free energy of solvation and on calculation of molecular properties. The PCM model was consistent with the experimental observations, the RDX in AAA conformation was predicted to be strongly favored in a condensed dielectric medium excluding that the distortion associated with the NO2 groups has not been found.