Thermal safety evaluation in the synthesis process of FOX-7 (1,1-diamino-2,2-dinitroethylene)
摘要
This paper evaluated the thermal hazards in the synthesis process of FOX-7 (1,1-diamino-2,2-dinitroethylene) using 2-methyl-4,6-dihydroxypyrimidine (DHMP) as the raw material. Thermogravimetry–differential scanning calorimetry (TG-DSC) was employed to analyze the thermal stability of DHMP and FOX-7. The results show that: DHMP undergoes significant endothermic decomposition within the temperature range of 317.29–340.75 °C, and its decomposition activation energy was calculated; FOX-7 exhibits an endothermic crystal transformation and a two-stage decomposition process, with the average activation energy of the first stage decomposition being 248.36 kJ mol−1. Accelerating rate calorimetry (ARC) was used to test the adiabatic stability of the nitrification liquid, hydrolysis liquid, and FOX-7, while the exothermic behavior during the reaction process was monitored via reaction calorimetry (Easymax). Under the scenario of cooling failure, the maximum temperature of synthesis reaction (MTSR) of the nitrification reaction and hydrolysis reaction reached 59.01 °C and 28.76 °C, respectively. According to the Stossel reaction classification method, both the nitrification reaction and hydrolysis reaction are classified as “Class 2”, indicating that these two reactions have potential decomposition hazards during industrial operation. The results provide key thermal safety parameters and risk assessment basis for the safe scale-up and industrial production of FOX-7.