Kinetics and mechanism of the thermal decomposition of keto-RDX

The thermal decomposition of keto-RDX occurs through the homolysis of the N-NO₂ bond in one of the nitramide groups. This bond is substantially longer (1.438 Å) than the analogous bond in the RDX molecule (1.382 Å). The activation parameters of the decomposition, E (kcal/mol) and logA [s^?1] were found to be 36.2 and 14.8 in benzene and 35.4 and 12.84 in the solid phase. In the latter case, the reaction proceeds through the dislocation mechanism. The crushing of large crystals produces no effect on the decomposition rate, which, however, depends on the regime of crystallization. The rearrangement into unstable diazoxy esters, a process typical of linear nitramides, does not occur in keto-RDX because of steric hindrances.