Energy properties and thermal decomposition kinetics of triazine derivatives

摘要

A trinitromethyl group is specific of a high oxygen balance and therefore it is of considerable interest as a fragment of high energy molecules. Researches on the synthetic pathways for trinitromethyl derivatives of heterocyclic compounds are growing in number each year. However the publications, as a rule, do not communicate experimental data on the enthalpy of formation and thermal stability. This paper discusses the thermomechanical and kinetic properties of a few 1,3,5-triazines that incorporate trinitromethyl and azide substituents. Syntheses and measurements of combustion energies were performed until a complete convergence of combustion energies within a few batches of specimens. Calorimetric measurements of combustion energies were done using a precision automatic calorimeter of combustion with an isothermal jacket. The kinetics of liquid phase thermal decomposition of 1,3,5-triazines in the isothermal conditions was studied by a manometric method. Gaseous decomposition products were identified by mass spectrometry in combination with a fractional condensation method. The kinetics of thermal decomposition of 2,4-diazido-6-trinitromethyl-1,3,5-triazine and its derivatives was described by a first order equation. Rate constants, activation energies and pre-exponential reaction factors were determined. Dissociation energies of the C-NO2 bond were found. The composition of gaseous products of thermal decomposition was defined. 1R spectra of the reagents and their decomposition products were reviewed. A decay of the trinitromethyl group appeared a limiting reaction step. Thermal decomposition in the non-isothermal conditions proceeded by two macroscopic stages and of note is that the trinitromethyl group decomposed in the first stage. Aggregate stoichiometric equations for the reactions were derived.