Ab initio study of the reaction of propionyl (C2H5CO) radical with oxygen (O2)
Ab initio study of the reaction of propionyl (C2H5CO) radical with oxygen (O2)
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DOI：
10.1063/1.2756538
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发表时间：
2007-08-07
影响因子：
4.4
通讯作者：
Wang, Baoshan
中科院分区：
文献类型：
--
作者：
Hou, Hua;Wang, Baoshan
利用具有完整基础集的全耦合簇理论研究了丙酰自由基与氧的反应。这是第一次详细了解这一重要反应的反应机理和动力学。该反应通过化学活化机制发生。丙酰基与氧的无障碍缔合产生丙酰基过氧自由基，其分解形成羟基自由基和主要的三中心α-内酯或四中心β-丙内酯。丙酰自由基氧化成一氧化碳或二氧化碳并不简单，而是通过α-内酯和β-丙内酯的二次分解。从动力学上讲，总体速率常数几乎与压力无关，并且接近数十托氦气的高压极限。在低于 600 K 的温度下，速率常数表现出负温度依赖性。羟基自由基的实验产率可以很好地再现，每次碰撞传递的平均能量在213和295 K（氦浴气体）下为-=20-25 cm(-1)。在低压下，α-内酯与羟基自由基一起是主要产物，而β-丙内酯仅占α-内酯的五分之一左右。在高压极限下，丙酰过氧自由基和一小部分异构体的产生占主导地位。建议在未来的C2H5CO+O-2反应实验研究中采用红外光谱或质谱技术。 (c) 2007 年美国物理研究所。
The reaction of propionyl radical with oxygen has been studied using the full coupled cluster theory with the complete basis set. This is the first time to gain a conclusive insight into the reaction mechanism and kinetics for this important reaction in detail. The reaction takes place via a chemical activation mechanism. The barrierless association of propionyl with oxygen produces the propionylperoxy radical, which decomposes to form the hydroxyl radical and the three-center alpha-lactone predominantly or the four-center beta-propiolactone. The oxidation of propionyl radical to carbon monoxide or carbon dioxide is not straightforward rather via the secondary decomposition of alpha-lactone and beta-propiolactone. Kinetically, the overall rate constant is almost pressure independent and it approaches the high-pressure limit around tens of torr of helium. At temperatures below 600 K, the rate constant shows negative temperature dependence. The experimental yields of the hydroxyl radical can be well reproduced, with the average energy transferred per collision -=20-25 cm(-1) at 213 and 295 K (helium bath gas). At low pressures, together with the hydroxy radical, alpha-lactone is the major product, while beta-propiolactone only accounts for about one-fifth of alpha-lactone. At the high-pressure limit, the production of the propionylperoxy radical is dominant together with a fraction of the isomers. The infrared spectroscopy or the mass spectroscopy techniques are suggested to be employed in the future experimental study of the C2H5CO+O-2 reaction. (c) 2007 American Institute of Physics.