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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Thermochemical and Kinetic Analysis of the H, OH, HO↓(2), O, and O↓(2) Association Reactions with Cyclopentadienyl Radical
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Thermochemical and Kinetic Analysis of the H, OH, HO↓(2), O, and O↓(2) Association Reactions with Cyclopentadienyl Radical

机译：H，OH，HO↓（2），O和O↓（2）与环戊二烯基自由基缔合反应的热化学和动力学分析

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摘要

Reaction pathways and kinetics for cyclopentadienyl radical association with H, OH, HO↓(2), O, and O↓(2) are presented in the temperature range 900-1300 K and atmospheric pressure. Thermochemical data for reactants, intermediate, and product species are evaluated from literature data and from group additivity with hydrogen bond increments. High-pressure limit rate constants for the radical combination reactions and decomposition of the energized adducts are estimated. Pressure-dependent rate constants for each channel in the reaction systems are calculated using bimolecular quantum Rice Ramsperger Kassel, QRRK, for k(E) with a modified strong collision approach for falloff. A submechanism of important cyclopentadienyl radical reactions is assembled and tested in an elementary reaction model for combustion of benzene, where the cyclopentadienyl radical is a key intermediate in the stepwise (C6 →C5→C4) decomposition. Modeling results are compared with limited literature data on species profiles for appropriate reaction systems, where benzene, cyclopentadiene, and carbon monoxide are the initial fuel, observed intermediate, and major combustion product, respectively. H atom association with cyclopentadienyl radical (CY13PD5↑(·) leads to stabilized cyclopentadiene (CY13PD) as the primary product, with linear pentadienal diradical as a minor product. The hydroxyl association with cyclopentadienyl radical forms an energized adduct, which primarily rearranges to cyclopentadienol isomers, which are stabilized. O↑(3p) association with cyclopentadienyl radical leads to two main product sets: cyclopentadienone plus H atom or 1,3-butadienyl radical plus carbon monoxide. Hydroperoxy radical combination with cyclopentadienyl radical forms an energized hydroperoxy-cyclopentadiene, which can dissociate to lower energy products cyclopentenoxy radical plus OH, to cyclopentadienone + H↓(2)O, or back to the initial reactants. Oxygen molecule addition to cyclopentadienyl radical forms an energized cyclopentadiene peroxy radical with a very shallow well (ca. 13 kcal/mol), which predominantly dissociates back to reactants. A small, but important, fraction of the energized peroxy adduct undergoes reactions that lead to ring-opening with formation of resonance-stabilized 2-pentenedialdehyde radical or vinyl ketene and formyl radical. These reactions provide paths for cyclopentadienyl radical conversion to linear, unsaturated, oxyhydrocarbons.
机译：在900-1300 K的温度范围和大气压下，给出了环戊二烯基与H，OH，HO↓（2），O和O↓（2）缔合的反应途径和动力学。反应物，中间体和产物种类的热化学数据是根据文献数据和具有氢键增量的基团加和性进行评估的。估计了自由基结合反应和加成加合物分解的高压极限速率常数。使用双分子量子莱斯·拉姆斯伯格·卡塞尔（QRRK）对于k（E）使用改进的强碰撞方法衰减来计算反应系统中每个通道的压力依赖性速率常数。重要的环戊二烯基自由基反应的子机理已组装并在用于燃烧苯的基本反应模型中进行了测试，其中环戊二烯基自由基是逐步（C6→C5→C4）分解的关键中间体。将建模结果与有关适当反应系统的物种分布的有限文献数据进行比较，其中苯，环戊二烯和一氧化碳分别是初始燃料，观察到的中间产物和主要燃烧产物。 H原子与环戊二烯基自由基（CY13PD5↑（·）缔合，以稳定的环戊二烯（CY13PD）为主要产物，而线性戊二烯基二自由基为次要产物;与环戊二烯基的羟基缔合形成能加成的加合物，主要重排为环戊二烯异构体O↑（3p）与环戊二烯基缔合产生两个主要产物集：环戊二烯酮加H原子或1,3-丁二烯基加一氧化碳。氢过氧自由基与环戊二烯基结合形成加能的氢过氧环戊二烯，可以分解成低能产物，环戊烯氧基基团加OH，分解成环戊二烯酮+ H↓（2）O，或返回到初始反应物。除环戊二烯基基团上的氧分子外，还形成了一个能量很强的环戊二烯过氧基团，孔很浅（约13 kcal） / mol），主要分解回反应物。很小但很重要的能量化的过氧加合物发生反应，导致开环并形成共振稳定的2-戊二醛基或乙烯基烯酮和甲酰基。这些反应提供了将环戊二烯基自由基转化为线性，不饱和氧基烃的途径。

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