Solid state thermochemical decomposition of neat 1,3,5,5-tetranitrohexahydropyrimidine (DNNC) and its DNNC-d6 perdeuterio-labeled analogue

The solid state thermochemical decomposition kinetics and activation energy of neat 1,3,5,5-tetranitrohexahydropyrimidine (DNNC) and its DNNC-d6 deuterium labeled analogue were obtained by isothermal differential scanning calorimetry (IDSC) at 142, 145, and 148DDGC. Global rate constants and kinetic deuterium isotope effect (KDIE) data from the exothermic decomposition process suggest that homolytic C?H bond rupture, in one or both types of chemically non-equivalent methylene (?CH2) groups of the DNNC ring structure, constitutes the exothermic rate-controlling step. A DNNC-d6 energy of activation equal to 115kJ/mol was determined for this initial autocatalytic exothermic energy release from which a 106kJ/mol activation energy was calculated for unlabeled DNNC. This exothermic autocatalytic decomposition process follows an extended endothermic induction period for DNNC which shows a higher 128kJ/mol activation energy during which a catalytic initiating species may form by a rate-controlling step different from C?H bond rupture.