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.