The gas-phase ozonolysis reaction of methylbutenol: A mechanistic study

The gas-phase ozonolysis reaction of methylbutenol through the Criegee mechanism is investigated. The initial reaction leads to a primary ozonide (POZ) formation with barriers in the range of 10-28 kJ mol(-1). The formation of 2-hydroxy-2-methyl-propanal (HMP) and formaldehyde-oxide is more favorable, by 10 kJ mol(-1), than the syn-CI and formaldehyde. The unimolecular dissociation of the more stable syn-CI via 1,5-H transfer into an epoxide is more favored than the epoxide and O-3(2) formation. The ester channel led to the formation of the acetone and formic acid favorably from the anti-CI. The hydration of the anti-CI with H2O and (H2O)(2) is significantly barrierless with a higher plausibility to the latter, and thus they may lead to the formation of peroxides and ultimately OH radicals, as well as airborne particulate matter. Reaction of anti-CI with water dimers enhances its atmospheric reactivity by a factor of 28 in reference to water monomers.