Solid State Versus Liquid State Thermochemical Decomposition Comparison of 1,3,5,5-Tetranitrohexahydropyrimidine (DNNC) and DNNC-d_6: Role of Chemical Structure Revisited

摘要

The solid-state (142 to 148°C) and liquid-state (174 to 194°C) thermochemical decomposition processes of neat 1,3,5,5-tetranitrohexahydropyrimidine (DNNC, mp = 155-156°C) and its perdeuterio DNNC-d_6 deuterium-labeled analogue were investigated by isothermal differential scanning calorimetry (IDSC), and the similarities and differences between each are compared. The kinetic deuterium isotope effect (KDIE) approach identified the rate-controlling-step in each state that determines the overall rate at which each decomposition process is initiated and subsequently proceeds. IDSC data obtained from DNNC, DNNC-d_2, DNNC-d_4, and DNNC-d_6 liquid state thermochemical decompositions provide an intramolecular-based KDIE approach to identify the specific site in the unsymmetrical DNNC molecule where the rate-controlling chemical bond rupture regulates its overall exothermic energy release process.