Atmospheric Chemistry of Enols: The Formation Mechanisms of Formic and Peroxyformic Acids in Ozonolysis of Vinyl Alcohol

Oxepin Derivatives Formation from Gas-Phase Catechol Ozonolysis

Quantum chemical calculations are performed to explore all of the possible pathways for primary ozonide (POZ) formation from gas-phase ozonolysis of catechol. Canonical transition state theory has been used to calculate the rate coefficients of individual steps for the formation of POZ. The calculated rate coefficients for 1,3-cycloaddition of ozone at the (i) unsaturated C(OH)═C(OH) bond and (ii) CH═C(OH) of catechol, respectively, are in good agreement with the experimental rate constant. In general, subsequent decomposition of POZ leads to well-known Criegee Intermediates. This work reveals a parallel pathway by which the endo-addition of ozone at CH═C(OH) of catechol proceeds through oxepin derivatives along with the paths leading to Criegee Intermediates and peroxy acids. The 7-membered heterocyclic oxepin derivatives have lower energies than Criegee Intermediates but similar relative energies with peroxy acids.

Unimolecular and water reactions of oxygenated and unsaturated Criegee intermediates under atmospheric conditions

Ozonolysis of unsaturated hydrocarbons (VOCs) is one of the main oxidation processes in the atmosphere. The stabilized Criegee intermediates (SCI) formed are highly reactive oxygenated species that potentially influence the...