THERMAL-DECOMPOSITION OF NITRAMINES - DIMETHYLNITRAMINE, DIISOPROPYLNITRAMINE, AND N-NITROPIPERIDINE

Kinetics and activation parameters of the solution thermolysis of nitramines dimethylnitramine, diisopropylnitramine, and N-nitropiperidine were determined over the temperature range 200-300-degrees-C. Each formed the corresponding nitrosamine as the only, or major, condensed-phase product. For dimethylnitramine the products were completely characterized. The observations of a large positive activation volume in the thermolysis of dimethylnitramine and of the slowing of the decomposition reaction with increased solvent viscosity both suggest that the rate-determining step is homolysis, the N-NO2 bond being the most obvious point for this. Nitrosamines could be produced by this route; however, when doubly N-15-labeled dimethylnitramine was heated with unlabeled dimethylnitramine, little scrambling of the label in the reactant was observed. Label scrambling was observed in the nitrosamine but could have resulted from subsequent N-NO homolysis. Scrambling of the label in the product gases and the observation of a kinetic isotope effect when perdeuterated dimethylnitramine was decomposed were explained in terms of a second decomposition route involving transfer of hydrogen from the alpha carbon to one of the NO2 oxygens.