Study on thermal decomposition and thermal hazard analysis of azobenzene-4,4'-dicarboxylic acid dimethyl ester

Recently, azobenzene-4,4'-dicarboxylic acid dimethyl ester (AADE) has been widely employed as the reagent and intermediate in organic reactions. However, in which structure, the N = N double bond is easily broken down by heating, resulting in serious accidents on fire and explosion. Here, the thermal decomposition of AADE was investigated by means of differential isotropic transformation, compensation parameter approach, and evaluation of nonlinear fitting; the thermodynamic and kinetic parameters were analyzed to reveal its decomposition mechanism; and the self-accelerating decomposition temperature (SADT) was calculated to assess its thermal hazard. The results show that the exothermic heat of AADE fluctuates within the range of 790.85–895.69 kJ kg⁻¹; the activation energies vary from 78.60 to 90.96 kJ mol⁻¹ at conversion rates of 0.05–0.40; the thermal decomposition behavior can be described by the exponential model. According to the Frank-Kamenetskii model, the AADE’s calculated SADT is 216.37 °C, when packed in 25 kg standard package. It is of great practical significance for the prevention of public safety accidents.