Thermal Conversions of 2,4-Bis(N,N-Dimethylamino)-6-Trinitromethyl-1,3,5-Triazine

To predict the thermal stability of high-energy triazine derivatives and the compatibility of trini-tromethyl substituents with dialkylamino groups in particular, thermal conversions of 2,4-bis(N, N-dimethyl-amino)-6-trinitromethyl-1,3,5-triazine (I) have been investigated in a temperature range of 170–623 K via differential thermal analysis, mass spectrometry, and single-crystal and powder X-ray diffraction. Compound I is characterized by a strong anisotropy of temperature expansion, and at 365 K it undergoes α-I → β-I polymorphic transformation that is preceded by an abrupt drop in density. A polymorphic transformation occurs with the destruction of crystals and is accompanied by the partial mechanochemical decomposition of I. The melting of I at about 396 K results in abrupt acceleration of its decomposition. The thermal effects of the polymorphic transformation, melting, and decomposition of I have been measured. The activation parameters of decomposition of I in melt have been estimated based on the data of differential scanning calorimetry. The composition of the gaseous products being formed has been determined, and mechanism of decomposition of I has been proposed, according to which the dimethylamino group is oxidized by the nitro group at the limiting stage of the process.