Theoretical study on the structure and the isomerization mechanism of N-nitropyrazole

N-nitropyrazole, as a kind of important intermediate, is used to synthesize the novel energetic material. Therefore, it is necessary to get an insight into the isomerization mechanism. Herein, we propose three reaction pathways. Quantum chemistry theory was used to calculate the structure, energy, and thermal parameter. Pathway A is the main path with the lowest energy barrier. The theoretical rate constant is 0.022 min(-1) which has a good agreement with the experimental result of 0.021 min(-1). The proton shift was also studied to confirm that 2H-3-nitropyrazole is the final production.