Atmospheric Degradation\nof CH<sub>2</sub>C(CH<sub>3</sub>)C(O)O[CH<sub>2</sub>]<sub>4</sub>CH<sub>3</sub> by <sup>•</sup>OH Radicals: Reactivity,\nPOCP, and Carbonyl Formation

Relative\nrate studies of the gas-phase reaction of amyl methacrylate,\nCH<sub>2</sub>C(CH<sub>3</sub>)C(O)O[CH<sub>2</sub>]<sub>4</sub>CH<sub>3</sub>, with <sup>•</sup>OH radicals were performed\nat (298 ± 2) K and 1000 mbar. The experiments were conducted\nin an atmospheric Pyrex chamber coupled to <i>in situ</i> Fourier transform infrared spectroscopy (FTIR). The rate coefficient\nobtained from the average of several experiments was <i>k</i><sub>AMMA+•OH</sub> = (8.10 ± 1.98) × 10<sup>–11</sup> cm<sup>3</sup> molecule<sup>–1</sup> s<sup>–1</sup>. Additionally, product studies were conducted under conditions similar\nto those of the kinetic experiments by using <i>in situ</i> FTIR spectroscopy. Pentanal, butanal, and hydroxyacetone were identified\nas the main reaction products. The initial pathway for the degradation\nof amyl methacrylate with <sup>•</sup>OH radicals occurs via\naddition of <sup>•</sup>OH to the >CC< bond or\nhydrogen\nabstraction from the alkyl chain of the ester. The likelihood of hydrogen\natom abstraction is 25%, while the addition of hydroxyl radicals to\nthe double bond occurs with a probability of 75%. Based on these outcomes,\na degradation mechanism is postulated. Furthermore, the atmospheric\nimplications of the studied reaction were evaluated by estimating\nthe tropospheric lifetime of amyl methacrylate toward <sup>•</sup>OH radicals as τ<sub>OH</sub> = 3.43 h. Additionally, the Photochemical\nOzone Creation Potential (POCP) of 84 was calculated for the reaction\nstudied. Carbonyl compounds found as reaction products can exert a\nsubstantial influence on both air quality and public health.