Solid State Thermochemical Decomposition of Neat 1,3,5,5-Tetranitrohexahydropyrimidine (DNNC) and Its DNNC-d6 Perdeuterio-Labeled Analogue (PREPRINT)
AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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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 148 oC. 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 115 kJmole was determined for this initial autocatalytic exothermic energy release from which a 106 kJmol activation energy was calculated for unlabeled DNNC. This exothermic autocatalytic decomposition process follows an extended endothermic induction period for DNNC which shows a higher 128 kJmole activation energy during which a catalytic initiating species may form by a rate-controlling step different from C-H bond rupture.
- Physical Chemistry
- Organic Chemistry