Thermal Risk Analysis Based on Reaction Mechanism: Application to the 2,6-Diaminopyrazine-1-oxide Synthesis Process

Abstract

Thermal risk analysis is essential for the development of chemical reactions. This work should be carried out on the basis of a thorough comprehension of the reaction mechanism. In this article, the synthesis process for 2,6-diaminopyrazine-1-oxide (DAPO), an important intermediate in the synthesis of the famous explosive 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), was employed to show the importance of understanding the reaction mechanism for thermal risk analysis. First, we investigated the reaction mechanism of DAPO synthesis. The reaction mechanism was divided into two stages on the basis of the amount of triethylamine dosed: the first half of triethylamine dosing and the second half of triethylamine dosing until the end of the reaction. Then the thermal properties of DAPO synthesis and the thermal stability of the materials involved were experimentally studied using a reaction calorimeter (RC1) and a differential scanning calorimeter (DSC), respectively. The results show that the temperature corresponding to the maximum reaction rate reached in a time of 24 h under adiabatic conditions (TD24) is higher than the maximum temperature of the synthesis reaction (MTSR) for both of these stages, indicating that once cooling failure occurs, immediately stopping addition of triethylamine could prevent the occurrence of secondary decomposition.