Synthesis, thermal hazard analysis and density functional theory study of nitroimidazoles

To understand the thermal decomposition mechanism and performance of nitroimidazoles, 1,4-dinitroimidazole (1,4-DNI), 2,4-dinitroimidazole (2,4-DNI) and 4,5-dinitroimidazole (4,5-DNI) were synthesized by 4-nitroimidazole firstly and all of them were studied using Differential Scanning Calorimetry (DSC), Accelerating Rate Calorimetry (ARC) and Density Functional Theory (DFT). The experiments show that among the four nitroimidazoles, the decomposition temperature and apparent activation energy of 1,4-DNI are relatively low. Theoretical calculations show that compared with C[sbnd]NO₂, N[sbnd]NO₂ is easier to break from the imidazole ring, and the detonation performance of 1,4-DNI is the best among the four nitroimidazoles. Dinitroimidazoles all contain two nitro groups, resulting in their sensitivity and energy much greater than 4-NI. Since 1,4-DNI is the only substance containing N[sbnd]NO₂, the chemical activity of 1,4-DNI is further improved. In addition, 1,4-DNI has relatively excellent detonation performance, which can be used as the research direction of new energetic materials.