In this study, the density functional theory (DFT) and CCSD(T) method have been performed to gain insight into the possible products and detailed reaction mechanism of the Criegee intermediate (CI) of anti-PhCHOO with SO2 for the first time. The potential energy surfaces (PESs) have been depicted at the UCCSD(T)/6-311++G(d,p)//UB3LYP/6-311++G(d,p) levels of theory with ZPE correction. Two different five-membered ring adducts, viz., endo PhCHOOS(O)O (IM1) and exo PhCHOOS(O)O (IM2) have been found in the entrance of reaction channels. Both direct and indirect reaction pathways from IM1 and IM2 have been considered for the title reaction. Our calculations show that the formation of PhCHO+SO3 (P1) via indirect reaction pathways from IM1 is predominant in all the pathways, and the production of P1 via direct dissociation pathway of IM1 and indirect reaction pathways of IM2 cannot be neglected. Moreover, PhCOOH+SO2 (P2) initiated from IM2 is identified as the minor product. According to the kinetic calculation, the total rate constant for the anti-PhCHOO+SO2 reaction is estimated to be 6.98 × 10−10 cm3·molecule−1·s−1 at 298 K.

中文翻译：

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Criegee 中间体与 SO2 抗 PhCHOO 反应机理和动力学的理论洞察

本研究首次通过密度泛函理论（DFT）和CCSD（T）方法深入了解了抗PhCHOO的Criegee中间体（CI）与SO2的可能产物和详细反应机理。势能面 (PES) 已在 UCCSD(T)/6-311++G(d,p)//UB3LYP/6-311++G(d,p) 理论水平与 ZPE 校正进行描述。在反应通道的入口处发现了两种不同的五元环加合物，即内型 PhCHOOS(O)O (IM1) 和外型 PhCHOOS(O)O (IM2)。来自 IM1 和 IM2 的直接和间接反应途径都已被考虑用于标题反应。我们的计算表明，通过 IM1 的间接反应途径形成 PhCHO+SO3 (P1) 在所有途径中占主导地位，不可忽视通过IM1的直接解离途径和IM2的间接反应途径产生P1。此外，由 IM2 引发的 PhCOOH+SO2 (P2) 被确定为次要产物。根据动力学计算，反PhCHOO+SO2反应的总速率常数在298 K时估计为6.98 × 10−10 cm3·molecule−1·s−1。