New thermal decomposition pathway for TATB

Understanding the thermal decomposition behavior of TATB (1,3,5-triamino-2,4,6-trinitrobenzene) is a major focus in energetic materials research because of safety issues. Previous research and modelling efforts have suggested benzo-monofurazan condensation producing H₂O is the initiating decomposition step. However, early evolving CO₂ (m/z 44) along with H₂O (m/z 18) evolution have been observed by mass spectrometric monitoring of head-space gases in both constant heating rate and isothermal decomposition studies. The source of the CO₂ has not been explained, until now. With the recent successful synthesis of ¹³C₆-TATB (¹³C incorporated into the benzene ring), the same experiments have been used to show the source of the CO₂ is the early breakdown of the TATB ring, not adventitious C from impurities and/or adsorbed CO₂. A shift in mass m/z 44 (CO₂) to m/z 45 is observed throughout the decomposition process indicating the isotopically labeled ¹³C ring breakdown occurs at the onset of thermal decomposition along with furazan formation. Partially labeled (N¹⁸O₂)₃-TATB confirms at least some of the oxygen comes from the nitro-groups. This finding has a significant bearing on decomposition computational models for prediction of energy release and deflagration to detonation transitions, with respect to conditions which currently do not recognize this oxidation step.