OH Roaming as a Key Pathway in the Anti-CH3CHOO + H2O Reaction Yielding CH3COOH and H2O

The reaction of anti-CH3CHOO with H2O is a crucial atmospheric process, resulting in the end products CH3COOH + H2O through the dissociation of the intermediate hydroxyethyl hydroperoxide (CH3CH(HO)OOH, HEHP). Based on an accurate full-dimensional PES, we have obtained detailed dynamics information for this reaction through quasi-classical trajectory simulations. We report two reaction mechanisms for the CH3COOH + H2O product channel: one involving a direct mechanism through the transition state and the other an intriguing OH roaming mechanism. The roaming pathway proceeds via the dissociation of HEHP into OH and the hydroxyethoxy radical (CH3CH(HO)O, HEO), where the OH radical roams near HEO and abstracts a hydrogen atom, subsequently forming H2O and CH3COOH. The presence of this roaming pathway significantly increases the yield of CH3COOH + H2O. This work provides new dynamical support for the study of the anti-CH3CHOO + H2O reaction and enriches our understanding of atmospheric chemistry.