posted on 2023-12-30, 04:29authored byShankupar Rynjah, Bhabesh Baro, Biplab Sarkar
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) CHC(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 CHC(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.