Thermal decomposition characteristics of diethyl azodicarboxylate dissolved in three ionic liquids as solvents

Azo-peroxyester, a multifunctional elemental energetic material, has low efficiency when indirectly acting on the target product in a reaction. If azo-peroxyester is dissolved in an appropriate solvent, the yield is greatly improved. With the aim of perfecting the safety of diethyl azodicarboxylate (DEAD) in industrial process applications, this study evaluated the inherent safety of DEAD when dissolved in different reagents by using differential scanning calorimetry and a thermal activity monitor III. The thermokinetic parameters, exothermic onset temperature (T-o), time to maximum rate under isothermal conditions (TMRiso), and apparent activation energy (E-a), were determined in order to reveal factors influencing the reaction mechanism. Comparing with pure DEAD, T-0 was lower when DEAD was dissolved in three ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium bis (trifluoromethyl)sulfonyl)imide. Additionally, E-a and TMRiso were considerably higher, indicating there was an improvement in both efficiency and thermal safety of DEAD for the reaction process. These results support the applications of DEAD in industrial process safety, and set a foundation for future laboratory investigation. (C) 2020 Elsevier B.V. All rights reserved.