Mechanisms of Nitramine Thermolysis

The thermal decomposition of a number of nitramines was studied in dilute solution and in the melt. The nitramines included acyclic mononitramines [dimethylnitramine (DMN), diethylnitramine (DEN), dipropylnitramine (DPN), and diisopropylnitramine (DIPN)], cyclic mononitramines [N-nitro-piperidine (NPIP) and N-nitropyrrolidine (NPyr)], cyclic dinitramines [N-dinitropiperazine (pDNP), 1,3-dinitro-1,3-diazacyclopentane (DNI), and 1,3-dinitro-1,3-diazacyclohexane (mDNP)], and 1,3,5-trinitro-1,3,5-triazocyclohexane (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX), hexanitro-hexaazaisowurtzitane (HNIW), and 1,3,3-trinitroazetidine (TNAZ). For the acyclic and cyclic mono- and di-nitramines, the corresponding nitrosamines were the only or major condensed-phase product. Kinetics and activation parameters were determined for the thermolysis of dilute solutions (0.01 to 1.0 wt%) over range 200o to 300oC. The thermolyses were found to be first-order with the rate constants unaffected by use of deuterated solvent. As the nitramines became more complex than dimethylnitramine (DMN), the rate of decomposition increased and the product distribution became more complex. As the length of the aliphatic chain increased (DMN < DEN < DPN), the