Lyon Richard E
Aviation Research Division, Federal Aviation Administration W. J. Hughes Technical Center, Atlantic City International Airport, Egg Harbor Township, New Jersey 08405, United States.
J Phys Chem A. 2023 Mar 16;127(10):2399-2406. doi: 10.1021/acs.jpca.2c07715. Epub 2023 Mar 3.
Kinetic compensation is a strong, positive correlation between the Arrhenius activation energy and the frequency factor for a reaction between the same reactants under similar experimental conditions or similar reactants under the same conditions, even though these parameters are supposed to be independent. The kinetic compensation effect (KCE) is demonstrated by a linear relationship between ln[] and / in the eponymous Constable plot and has been the subject of more than 50 000 publications over the past 100 years, with no consensus opinion about the cause of this effect. In this paper, it is suggested that the linear relationship between ln[] and is the result of a real or spurious path dependence of the reaction history between the initial state of the pure reactant(s) and the final state of the pure product(s) having standard enthalpy and entropy differences, Δ° and Δ°, respectively. The single-step rate law approximation of a reversible reaction leads to = °/Δ° as the dynamic thermal (thermodynamic) equilibrium temperature and 1/ = (ln[/])/(/) as the slope of a Constable/KCE plot or the crossover temperature of Arrhenius lines in an isokinetic relationship (IKR), where and are mean values for the ensemble of compensating {, } pairs and is a constant that accounts for the path dependence of the reaction history and reconciles the KCE with the IKR. This proposed physical basis for the KCE and IKR is supported by qualitative agreement between Δ° and Δ° calculated from the statistics of compensating {, } pairs in the literature, and the difference in the standard enthalpies and entropies of formation of the products and reactants for thermal decomposition of organic peroxides, calcium carbonate, and poly(methyl methacrylate).
动力学补偿是指在相似实验条件下相同反应物之间或相同条件下相似反应物之间的反应中，阿仑尼乌斯活化能与频率因子之间存在的一种强烈的正相关关系，尽管这些参数被认为是相互独立的。动力学补偿效应（KCE）在同名的康斯特布尔图中表现为ln[]与/之间的线性关系，在过去100年里，超过50000篇出版物都围绕这一效应展开，但对于该效应的成因尚未达成共识。本文提出，ln[]与之间的线性关系是纯反应物初始状态与纯产物最终状态之间反应历史的真实或虚假路径依赖性的结果，纯产物的标准焓和熵差分别为Δ°和Δ°。可逆反应的单步速率定律近似导致 = °/Δ°作为动态热（热力学）平衡温度，1/ = (ln[/])/(/)作为康斯特布尔/KCE图的斜率或等动力学关系（IKR）中阿仑尼乌斯线的交叉温度，其中和是补偿{, }对集合的平均值，是一个常数，它考虑了反应历史的路径依赖性，并使KCE与IKR相一致。文献中补偿{, }对的统计数据计算得到的Δ°和Δ°与有机过氧化物、碳酸钙和聚（甲基丙烯酸甲酯）热分解产物和反应物的标准生成焓和熵差之间的定性一致性，支持了本文提出的KCE和IKR的物理基础。
