Synthesis of 1-Amino-2,4-Dinitroimidazole Optimized by Online Infrared Spectroscopy and its Energetic Properties

The optimization of the reaction conditions (solvent, reaction time, and aminating agent) for the synthesis of 1-amino-2,4-dinitroimidazole (3) by monitoring the reaction with online infrared spectroscopy is reported in this study. First, the thermal characteristics of 3 were studied by using differential scanning calorimetry (DSC; using heating rates of 2.5, 5, 10, and 20 K min⁻¹), thermogravimetric analysis (TG), and the thermal explosion method. The Kissinger and Ozawa methods were used to calculate the average activation energy for the formation of 3; with logarithmic frequency factors (ln A) of 21.04 and 9.62, and activation energies (E_a) of 98.68 and 102.28 kJ mol⁻¹, respectively. Compound 3 and its reaction precursors 2,4-dinitroimidazole (1) and 1,4-dinitroimidazole were characterized by single-crystal X-ray diffraction. Compound 3 is shown to have good energetic properties, as determined through EXPLO5 v6.02 and actual measurement. Furthermore, this energetic material is found to have low impact sensitivity (IS>40 J) and friction sensitivity (FS>360 N).