Theoretical studies on the structures, thermodynamic properties, detonation properties, and pyrolysis mechanisms of four trinitrate esters

Density function theory (DFT) has been employed to study the geometric and electronic structures of four trinitrate ester including nitroglycerin (NG), butanetriol trinitrate (BTTN), trimethanolethane trinitrate (TMETN) and trimethylolpropane trinitrate (TMPTN) at the B3LYP/6-31G∗ level. Their IR spectra were obtained and assigned by vibrational analysis. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were linearly related with the number of methylene groups as well as the temperature, obviously showing good group additivity. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that density, detonation velocity, detonation pressure are decrease with the increase of the number methylene groups. Thermal stability and the pyrolysis mechanism of the title compounds were investigated by calculating the bond dissociation energies (BDE) at the B3LYP/6-31G∗ level. For the nitrate esters, the ONO2 bond is a trigger bond during thermolysis initiation process.