A quantum mechanics investigation for RDX ring-opening reactions

Cyclotrimethylene trinitramine (RDX) is a commonly used ingredient in solid propellants and explosives. As a result, RDX has been the subject of many experimental and theoretical investigations to elucidate its liquid-phase and gas-phase decomposition. In our experimental effort involving FTIR spectroscopy and time of flight mass spectrometry of fast thermolysis of RDX, the results indicate that ring-opening occurs very early due to the presence of carbon-containing species, such as HCN, H₂CO, CO and CO₂. After a lengthy search using quantum mechanics, ring-opening and subsequent reactions have been identified. These ring-opening and subsequent reactions may occur in both liquid and gas phases. The quantum mechanics investigation is based on using density functional theory, as well as various basis sets. The liquid-phase studies use the CPCM solvation model with water as solvent within the Gaussian 09 program package. Intrinsic reaction coordinate calculations have also been performed to verify that the reactants indeed are connected to the expected products.