Theoretical Investigation On The Reaction Mechanism Of Formaldehyde With OH～X(X=-1, 0, +1)

Formaldehyde (HCHO) is not only an important contamination in atmosphere, but also an important intermediate in organic synthesis. Reaction of HCHO with OH radical is the most important way for HCHO consumption in troposphere. We consider all the possible reaction channels in the reaction of HCHO with OH for the first time. For comparison, we also study the reactions of HCHO with OH^- and OH⁺. Our results indicate that there are three reaction pathways in the reaction of HCHO with OH, i.e., H-abstraction, H₂ formation and H atom formation, among which the H-abstraction reaction is the dominant reaction pathway. In the case of OH^-, there are four possible channels, i.e., H-abstraction, H₂ formation, H₃O^- formation, as well as hydrogen symmetric transfer, among which H3O- formation channel is dominant. In the case of OH⁺, H₃O⁺ formation is the preferable channel among the five reaction pathways, i.e., water molecule formation, H₃O⁺ formation, H₂ formation, oxygen atom formation, and H₂O₂ formation. The most remarkable difference among the titled reactions is in H₂ formation channel. Concerted elimination process occurs in either of the ionic reaction systems, while stepwise elimination process occurs in the radical reaction system.