Reactivity of Criegee Intermediates toward Carbon Dioxide

Recent theoretical work by Kumar and Francisco suggested that the high reactivity of Criegee intermediates (CIs) could be utilized for designing efficient carbon capture technologies. Because the anti-CH₃CHOO + CO₂ reaction has the lowest barrier in their study, we chose to investigate it experimentally. We probed anti-CH₃CHOO with its strong UV absorption at 365 nm and measured the rate coefficient to be ≤2 × 10^-17 cm³ molecule^-1 s^-1 at 298 K, which is consistent with our theoretical value of 2.1 × 10^-17 cm³ molecule^-1 s^-1 at the QCISD(T)/CBS//B3LYP/6-311+G(2d,2p) level but inconsistent with their results obtained at the M06-2X/aug-cc-pVTZ level, which tends to underestimate the barrier heights. The experimental result indicates that the reaction of a Criegee intermediate with atmospheric CO₂ (400 ppmv) would be inefficient (k_eff < 0.2 s^-1) and cannot compete with other decay processes of Criegee intermediates like reactions with water vapor (∼10³ s^-1) or thermal decomposition (∼10² s^-1).