Thermal Decomposition of Gas-Phase Bis(1,2,4-oxadiazole)bis(methylene) Dinitrate (BODN): A CCSD(T)-F12/DFT-Based Study of Reaction Pathways

Electronic structure methods based on density functional theory and coupled-cluster theory were employed to characterize elementary steps for the gas-phase thermal decomposition of bis(1,2,4-oxadiazole)bis(methylene) dinitrate (BODN). As typically found for nitrate ester-functionalized compounds, NO2 and HONO eliminations were the most energetically favorable unimolecular paths for the parent molecule's decomposition. From there, sequences of unimolecular reactions for daughters of the initiation steps were postulated and characterized. For intermediates found to have barriers to unimolecular decomposition that would make their rate at the temperatures and time scales of interest negligible, their decomposition via H-atom abstraction and radical-addition reactions was characterized. Creating a comprehensive network that can be employed to develop a detailed finite-rate chemical kinetics mechanism for simulating BODN's decomposition, the results provide a basis for modeling BODN's combustion, as well as its response to thermal loads germane to its aging, storage, and handling.