Mechanistic and Kinetic Approach on the Propargyl Radical (C3H3) with the Criegee Intermediate (CH2OO)

The detailed reaction mechanism and kinetics of the C3H3 + CH2OO system have been thoroughly investigated. The CBS-QB3 method in conjunction with the ME/ vRRKM theory has been applied to figure out the potential energy surface and rate constants for the C3H3 + CH2OO system. The C3H3 + CH2OO reaction leading to the CH2-[cyc-CCHCHOO] + H product dominates compared to the others. Rate constants of the reaction are dependent on temperatures (300-2000 K) and pressures (1-76,000 Torr), for which the rate constant of the channel C3H3 + CH2OO-* CH2-[cyc-CCHCHOO] + H decreases at low pressures (1-76 Torr), but it increases with rising temperature if the pressure P >= 760 Torr. Rate constants of the three reaction channels C3H3 + CH2OO-* CHCCH2CHO + OH, C3H3 + CH2OO-* OCHCHCHCHO + H, and C3H3 + CH2OO-* CHCHCHO + CH2O fluctuate with temperatures. The branching ratio of the C3H3 + CH2OO-* CH2-[cyc- CCHCHOO] + H channel is the highest, accounting for 51-98.7% in the temperature range of 300-2000 K and 760 Torr pressure, while those of the channels forming the products PR10 (OCHCHCHCHO + H) and PR11 (CHCHCHO + CH2O) are the lowest, less than 0.1%, indicating that the contribution of these two reaction paths to the title reaction is insignificant. The proposed temperature-and pressure-dependent rate constants, together with the thermodynamic data of the species involved, can be confidently used for modeling CH2OO-related systems under atmospheric and combustion conditions.

Automated summary

The detailed reaction mechanism and kinetics of the C3H3 + CH2OO system have been explored using the CBS-QB3 method and ME/vRRKM theory. The dominant reaction channel is C3H3 + CH2OO-* CH2-[cyc-CCHCHOO] + H. The rate constants of the reaction are dependent on temperature and pressure, with the highest branching ratio observed for the CH2-[cyc-CCHCHOO] + H channel.