Atmospheric Autoxidation Chemistry of Diethyl Ether

We report estimates of the rate coefficients for atmospheric autoxidation chemistry of diethyl ether (DE), a simple aliphatic ether, as a representative for the ether family, an important class of volatile chemical products (VCPs). We perform chamber experiments to estimate the rate coefficients of the H-shift reactions of peroxy radicals (RO2) formed by hydroxyl radical (OH) oxidation of DE relative to the rate coefficients of their reaction with HO2. We also estimate these rate coefficients for the fully deuterated version, diethyl ether-d10 (DE-d10). Computational methods based on multi-conformer transition state theory are used to guide our interpretation of these rate coefficients. At ambient temperature (294 ± 1 K), H-shift rate coefficients of DE RO2 are estimated to be ∼0.09 ± 0.06 s–1, while those of DE-d10 RO2 are ∼8–15 times smaller due primarily to reduction in quantum tunneling. Our estimates agree well with theoretical predictions. The RO2 autoxidation rate coefficients are sufficiently fast to be competitive with their bimolecular reactions when NO levels are less than ∼1 ppb─common urban atmospheric conditions following the controls of NOx emissions, indicating efficient formation of highly oxygenated organic molecules (HOMs), which can be important secondary organic aerosol (SOA) contributors, from volatile ether compounds.