Crystal structure and thermal behaviors for 3,5-dinitrobenzoic acid of 3,5-diamino-1,2,4-triazole

• The crystal structure of the new ionic compound DAT·DNBA was determinated and analyzed.
• The thermal behavior and the decomposition reaction kinetics were investigated by means of DSC and RSFTIR.
• Some parameters were calculated to evaluate the thermal stability and safety.

3,5-Dinitrobenzoic acid of 3,5-diamino-1,2,4-triazole (DAT) salt (DAT·DNBA) was synthesized and its structure was characterized by element analysis, IR and single-crystal X-ray diffraction analysis. The thermal behavior was investigated with the methods of differential scanning calorimetry (DSC) and rapid scan Fourier transform infrared spectroscopy (in situ thermolysis/RSFTIR), and the thermal decomposition reaction kinetics was obtained by means of DSC technique at the different heating rate. The results show that there are two mass loss stages at the thermal decomposition process, and the apparent activation energy and pre-exponential factor of the exothermic decomposition reaction of DAT·DNBA obtained by five integral methods (General integral, MacCallum–Tanner, Šatava–Šesták, Agrawal, Flynn–Wall–Ozawa) and one differential method (Kissinger) are 226.37 kJ mol−1 and 1014.51 s−1 in the second decomposition stage. According to the change of the bond intensities, it can be deduced that hydronitrogen, oxynitride, and carbonitride should appear in the gaseous products breaking away from the condensed phase of DAT·DNBA. The groups of nitryl, amido and carboxyl have main contribution to some properties of the compound from the result of the quantum chemical calculation. The self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT) and the critical temperatures of thermal explosion (Tb) and the adiabatic time-to-explosion (tTIAD) is obtained as 660.25 K, 677.16 K, 691.70 K and 236 s, respectively. The detonation velocity (D) and pressure (p) were also estimated as 8358.86 m s−1 and 30.19 GPa. The above-mentioned information is quite useful for analysis and evaluating the stability and thermal safety of DAT·DNBA.