The reaction of the Criegee Intermediate (CI) with SO2 is believed to be a proficient source of H2SO4 in the atmosphere, presumably due to the ability of CI to convert SO2 to SO3. However, previous quantum chemical studies of the reaction mechanism have provided evidence of an alternative pathway in which the SO2 catalyzes the isomerization of the CI to a carboxylic acid. We have used the B3LYP/6-31+G(d,p) and CBS-QB3 model chemistries to obtain a mechanism for the CI-SO2 reaction that includes all possible diastereomers as well as diradical intermediates and transition structures. RRKM/master equation simulations on the parent CI-SO2 reaction predict branching ratios of 62% for SO3 + formaldehyde, 13% for SO2 + formic acid, and 25% for SO?2? + (bis)oxy diradical.

Quantum chemical and master equation studies of the reaction of the Criegee intermediate with sulfur dioxide

245th National Meeting (2013)

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