Temperature- and Pressure-Dependent Kinetics of the Criegee Intermediate (CH2OO) with Isomeric Heterocyclic Aldehyde: A Theoretical Study.

Temperature- and pressure-dependent kinetic study of the reactions of the Criegee intermediate (CH2OO) with 2-furaldehyde and 3-furaldehyde was performed by using computational methodologies. The geometry optimization and thermochemical parameters calculations were performed using B3LYP/6-311G+(2df,2p) theory, whereas the barrier heights in the potential energy diagram for the reaction pathways were calculated at the CCSD(T)-F12b/cc-pVTZ-F12//B3LYP/6-311 + G(2df,2p) level of theory. The room-temperature high-pressure-limit rate coefficients were calculated using canonical variational transition state theory in conjugation with small curvature tunneling (CVT/SCT) to be 7.20 × 10-12 cm3 molecule-1 s-1 and 3.04 × 10-12 cm3 molecule-1 s-1 for 2-furaldehyde and 3-furaldehyde, respectively. The room-temperature rate coefficients calculated from the MESMER were 2.62 × 10-12 cm3 molecule-1 s-1 and 1.59 × 10-12 cm3 molecule-1 s-1, respectively. The predicted products of the title reactions were formic acid and formaldehyde, along with 2-furoic acid for the 2-furaldehyde reaction and 3-furoic acid for the 3-furaldehyde reaction. The large value of atmospheric lifetimes (>400 days) of the furaldehydes due to their reactions with CH2OO suggests that the title reactions do not have any significant effect on the net atmospheric furaldehyde concentrations.