Kinetic and thermochemical studies of 2,4-bis(dimethylamino)-6-trinitromethyl-l ,3,5-triazine

摘要

The thermal decomposition of 2,4-bis(dimethylamino)-6-trinitromethyl-1,3,5-triazine (I) was studied under non-isothermal conditions by thermal analysis methods, as well as under isothermal conditions, both in melt and in dinonyl phthalate dilute solution, by means of manometric and gravimetric methods. The compound I is characterized by a strong anisotropy of thermal expansion and at 365 K undergoes a polymorphic transformation α-1→β-1 which is preceded by an abrupt drop in density. The polymorphic transformation is accompanied by partial mechanochemical decomposition of I. The composition of the gaseous decomposition products was analyzed by the mass spectrometry method. The heats of polymorphic transformations and thermal decomposition are determined. Under isothermal conditions, the reaction proceeds with self-acceleration. Additives of N-phenylmorpholine significantly accelerate the decomposition. It is concluded that the dimethylamine substituent in the molecule of the initial substance is directly involved in the rate determining stages of the process. The transition from the melt to the diluted solution leads to a strong slowing down of the reaction, which is not characteristic of the thermal decomposition of nitro compounds. This result is explained by the fact that some of the rate determining stages of the process is bimolecular. This is confirmed by the values of the activation parameters for the initial stages of thermal decomposition.