A theoretical study on gas-phase reaction of methylketene with OH: mechanism, kinetics, and insights

The oxidation mechanism of CH3CHCO initiated by OH is systematically studied using quantum theoretical methods. According to thermodynamic research, the dominant channel is the addition of CH3CHCO with OH generating C-IM1 (CH3CHOHCO) and C-IM2 (CH3CHCOOH), and then dissociate to the dominant products P1 (CH3CHO + CO) from C-IM1 with the lowest barrier. The rate constants for CH3CHCO + OH → C-IM1 → P1/CH3CHCO + OH → C-IM2 channels are computed through RRKM theory at 200–2000 K. The obtained overall rate constant at 298 K (7.60 × 10−11 cm3 molecule−1 s−1) is well consistent with the reported experimental value. The atmospheric lifetime of CH3CHCO is estimated to be around 1.83 h.