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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Radical-molecule reactions HCO/HOC + C2H2: Mechanistic study
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Radical-molecule reactions HCO/HOC + C2H2: Mechanistic study

机译：自由基分子反应HCO / HOC + C2H2：机理研究

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A detailed computational study is performed on the unknown radical-molecule reactions between HCO/ HOC and acetylene (C2H2) at the CCSD(T)/6-311G(2d,p)//B3LYP/6-311G(d,p)+ZPVE, Gaussian-3//B3LYP/ 6-31G(d), and Gaussian-3//MP2(full)/6-31G(d) levels. For the HCO + C2H2 reaction, the most favorable pathway is direct C-addition forming the intermediate HC=CHCH=O followed by a 1,3-H-shift leading to H2C=CHC=O, which finally dissociates to the product C2H3 + CO. The overall reaction barrier is 13.8, 10.5, and 11.3 kcal/mol, respectively, at the three levels. The quasi-direct H-donation process to produce C2H3 + CO with barriers of 14.0, 14.1, and 14.1 kcal/mol is less competitive. Thus only at higher temperatures could the HCO + C2H2 reaction play a role. In contrast, the HOC + C2H2 reaction can barrierlessly generate C2H3 + CO via the quasi-direct H-donation mechanism proceeding via a prereactive complex with OH (...) C-2 hydrogen bonding. This is suggestive of the potential importance of the HOC + C2H2 reaction in both combustion and interstellar processes. However, the direct C-addition channel is much less competitive. For both reactions, the possible formation of the intriguing interstellar molecules propadiene and propynal is also discussed. The present theoretical study represents the first attempt to probe the reaction mechanism between HOC and pi-systems. Future laboratory investigations on both reactions (particularly HOC + C2H2) are recommended.
机译：在CCSD（T）/ 6-311G（2d，p）// B3LYP / 6-311G（d，p）+处，对HCO / HOC与乙炔（C2H2）之间未知的自由基分子反应进行了详细的计算研究ZPVE，Gaussian-3 // B3LYP / 6-31G（d）和Gaussian-3 // MP2（full）/ 6-31G（d）的水平。对于HCO + C2H2反应，最有利的途径是直接C加成，形成中间体HC = CHCH = O，然后进行1,3-H移位，导致H2C = CHC = O，最后解离为产物C2H3 +在三个级别上，总的反应势垒分别为13.8、10.5和11.3 kcal / mol。准C氢捐赠过程产生的C2H3 + CO的势垒分别为14.0、14.1和14.1 kcal / mol。因此，只有在较高的温度下，HCO + C2H2反应才起作用。相比之下，HOC + C2H2反应可以通过准直接的H-给体机制无障碍生成C2H3 + CO，该机制通过与OH（...）C-2氢键结合的预反应性配合物进行。这表明HOC + C2H2反应在燃烧和星际过程中的潜在重要性。但是，直接的C加法渠道竞争性低得多。对于这两个反应，还讨论了有趣的星际分子丙二烯和丙炔的可能形成。目前的理论研究代表了首次探索HOC和pi系统之间反应机理的尝试。建议将来对这两种反应（尤其是HOC + C2H2）进行实验室研究。

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