Acetylacetone (AcAc) is a common atmospheric oxygenated volatile organic compound due to broad industrial applications, but its atmospheric oxidation mechanism is not fully understood. We investigate the mechanism, kinetics, and atmospheric fate of the OH-initiated oxidation for the enolic and ketonic isomers of AcAc using quantum chemical and kinetic rate calculations. OH addition to enol-AcAc is more favorable than addition to keto-AcAc, with the total rate constant of 1.69 × 10 exp(1935/T) cm molecule s over the temperature range of 200-310 K. For the reaction of the enol-AcAc with OH, the activation energies of H-abstraction are at least 4 kcal mol higher than those of OH-addition, and the rate constants for OH-addition are by 2-3 orders of magnitude higher than those for H-abstraction. Oxidation of AcAc is predicted to yield significant amounts of acetic acid and methylglyoxal, larger than those are currently recognized. A lifetime of less than a few hours for AcAc is estimated throughout the tropospheric conditions. In addition, we present field measurements in Beijing and Nanjing, China, showing significant concentrations of AcAc in the two urban locations. Our results reveal that the OH-initiated oxidation of AcAc contributes importantly to ozone and SOA formation under polluted environments.

The carbonyl-containing compounds (CCs) are typical volatile organic compounds (VOCs) and ubiquitously present in the environment. Therefore, the adsorption structures and properties of typical CCs on the anatase TiO2 (001) surface were investigated systematically with density functional theory (DFT) to understand their further catalytic degradation mechanisms. The adsorption mechanisms show that three selected typical CCs, acetaldehyde, acetone, and methyl acetate, can easily be trapped on the anatase TiO2 (001) surface via the interaction between the carbonyl group with Ti5c sites of catalyst surface. Especially for acetaldehyde with the bare carbonyl group and the strongest adsorption energy, it is the most stable on the surface, because the bare carbonyl group can interact with not only the Ti5c atom, but also the O2c atom of the surface. The substituent effect of different CCs has less impact on its adsorption models in this studied system and the bare carbonyl group is the key functional group within studied CCs. The Ti5c atoms of anatase TiO2 (001) surface are active sites to trap CCs. Our theoretical results are expected to provide insight into the adsorption mechanisms of these carbonyl-containing VOCs on TiO2 catalyst and also to help understand the further catalytic degradation mechanisms of air pollutants at the molecular level.