Thermal Decomposition of 1-[2,2-Bis(Metoxy-NNO-Azoxy)Ethyl]-3,4-Dinitro-1H-Pyrazole

The kinetics of thermal decomposition of 1-[2,2-bis(methoxy-NNO-azoxy)ethyl]-3,4-dinitro-1H-pyrazole is studied using isothermal and nonisothermal methods in a wide temperature range. The composition of the gaseous products, the heat of fusion, and the heat of thermal decomposition are determined. Below the melting temperature, the reaction proceeds with pronounced self-acceleration and cannot be described by simple kinetic laws. The effective activation energies of the process, which decrease as the degree of conversion increases, are calculated. The results obtained are explained from the point of view of general ideas about the mechanism of thermal decomposition of solid organic substances. In the liquid phase, the reaction proceeds with weak self-acceleration. The effective activation energies are also determined for the liquid-phase decomposition. It is assumed that the reaction proceeds according to a consecutive mechanism with the intermediate formation of a cyclic product. It is concluded that the studied 1-[2,2-bis(methoxy-NNO-azoxy)ethyl]-3,4-dinitro-1H-pyrazole is highly thermally stable and that the thermal stability of compounds of this class strongly depends on the number of nitro groups in the pyrazole ring.