Theoretical study on the formation of Criegee intermediates from ozonolysis of CH≡CCH2OH.

CONTEXT: H-abstraction and C≡C 1,3-cycloaddition mechanisms were discovered for the O3 + CH≡CCH2OH reaction. The computations manifested that the primary reaction channel is 1,3-cycloaddition involving O3 addition to the C≡C triple bond of CH≡CCH2OH to generate primary ozonide (IM1), which dissociated to generate two different Criegee intermediates (reactions of CI1 and CI2). The subsequent CI1 and CI2 were also detailedly investigated. The rate coefficients were also investigated at 200-3000 K and 10-10-1010 atm. At normal temperature and pressure, the rate coefficient was 4.46 × 10-19 cm3 molecule-1 s-1 with an atmospheric lifetime of 25.95 days. The current computation results have significant implications in the atmospheric chemistry of ozone oxidation of unsaturated alcohols.

METHODS

All calculations of electronic structure and energy in this study are implemented using Gaussian09. The geometries of all species for the O3 + CH≡CCH2OH reaction and subsequent reactions were optimized using the M06-2X method with the 6-311++G(d,p) basis set. All stationary points were determined for local minima and transition states through vibrational analysis, and connections of the transition states between designated reactants and products were proven through intrinsic reaction coordinate (IRC) computations. The energies for the potential energy surfaces (PES) were refined through the single-point computations using the CCSD(T)/cc-pVTZ level of theory. The rate constants for the title reaction and subsequent reactions had been computed with RRKM theory.