Theoretical and Experimental Study on the Inhibition of Diethyl Ether Oxidation

The inhibition mechanism of diethyl ether oxidation was investigated both at the experimental and theoretical (density functional theory, DFT) level to find the best inhibitor for such a process. First, a detailed theoretical analysis was conducted by DFT calculations on reactions with 12 potentially effective antioxidants from different chemical classes (phenols, amines, and phosphines). Results of this study show that phenolic antioxidants are the best performers for inhibiting the process. In particular, the efficacy of butylated hydroxytoluene, an additive already commonly used in diethyl ether (DEE) storage, was clearly explained from a kinetic (low activation barrier) and a thermodynamic (product stabilization) point of view. The order of effectiveness of the antioxidants obtained from DFT calculations was confirmed by the complementary experimental work on DEE oxidation, which were conducted under accelerated conditions in autoclaves.