Evidence of an Elimination Mechanism in Thermal Decomposition of Hexahydro-1,3,5-trinitro-1,3,5-triazine and Related Compounds under High Pressure in Solution

Abstract

The thermal decomposition of a number of six-membered cyclic nitramines and nitrosamines was studied under pressures up to 1.1 GPa in dilute solution (THF). The studied nitramines and nitrosamines include hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), hexahydro-5-methyl-1,3,5-trinitropyrimidine, hexahydro-1,3,5,5-tetranitropyrimidine, 1,3,3,5,5-pentanitropiperidine, and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TRDX). In all cases negative activation volumes have been found, indicating that thermolysis is not a homolytic process. On the basis of negative activation volumes, detection of aromatic products, low decomposition temperature (low E a ), and order of thermal stability, we propose that these cyclic nitramines and nitrosamines are thermally decomposed through the elimination of HNO 2 or HNO under high pressure. By summarizing our current and previous work, we find that the decomposition pathway of nitramines and nitrosamines is dependent not only on the reaction conditions but also on structural features.