Thermal decomposition of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX): Kinetics of nitroso intermediates formation

The kinetics of the thermal decomposition of RDX and the formation of three nitroso intermediates have been studied in hexaproteo (h 6) benzene; hexadeutero (d 6) benzene at 180°C and 200°C; and, as a melt at 210°C in sealed capillaries. Decomposition rates were determined by vapor-phase chromatographic analysia of the residues with time for unreacted RDX and the nitroso intermediates formed. RDX exhibited first order decomposition kinetics in benzene solutions, but showed zero order kinetics in the melt at 210°C. A kinetic isotope effect was observed in d 6-benzene, and together with the nitroso intermediates formation, indicated the following consecutive concurrent sequence as one decomposition pathway: RO 3 → RO 2 → RO → R → products, where RO 3 is RDX; and RO 2, RO, and R are the 1-nitroso-3,5-dinitro-, 1,3-dinitroso-5-nitro-, and the 1,3,5-trinitroso-1,3,5-triazacyclohexanes, respectively. Rate constants obtained for decomposition of RO 3 and RO 2 are discussed in terms of the nitroso intermediates formed.