Three ionic liquids as ‘‘smart’’ stabilizers for diethyl azodicarboxylate (DEAD)

As a homogeneous system consists of diethyl azodicarboxylate (DEAD) soluble in three ionic liquids (ILs), such as [BMIM][NTf₂], [BMIM][BF₄], [BMIM][PF₆], the catalytic efficiency can be substantially improved. However, their compatibility and stability have not yet been understood. The present study combines Thermal Safety Software (TSS) with Semenov theory in an in-depth analysis of experiment data to elucidate the reaction mechanism of DEAD with solvents effect. The characteristic thermokinetic parameters of DEAD dissolved in these three ILs, which TSS simulated, were high and consistent with the experimental values. Evidence was presented which showed that the thermal decomposition reaction mechanisms were determined as N-order model when DEAD soluble in the three ILs, and the order of the compatibility was: [BMIM][NTf₂] > [BMIM][BF₄] > [BMIM][PF₆]. In this paper, the simulated value of self-accelerating decomposition temperature (SADT) was 48 °C for DEAD soluble in [BMIM][PF₆] with a certain proportion, compared with the SADT value 43 °C calculated by Semenov theory. The research presented here confirms that 43 °C is the upper limit standard for the storage and transportation of DEAD, which paves a new avenue to facilitate the industrial process application of DEAD. The study concludes that three ILs are the smart stabilizers for DEAD, ameliorating its catalytic efficiency and thermal stability and laying a foundation for the rational design of catalysts toward green chemistry.