Department of Viticulture and Enology, University of California, Davis, California 95616, United States.
Department of Chemistry, University of California, Davis, California 95616, United States.
J Phys Chem B. 2023 May 18;127(19):4300-4308. doi: 10.1021/acs.jpcb.3c02172. Epub 2023 May 10.
Autoxidation of tartaric acid in air-saturated aqueous solutions in the presence of Fe(II) at low pH, 2.5, shows autocatalytic behavior with distinct initiation, propagation, and termination phases. With increasing pH, the initiation phase speeds up, while the propagation phase shortens and reduces to none. We show that the propagation phase is a chain reaction that occurs via activation of oxygen in the initiation stage with the production of hydrogen peroxide. The subsequent Fenton oxidation that regenerates hydrogen peroxide with a positive feedback is typical of a self-sustained chain reaction. The conditions for such a chain reaction are shown to be similar to those of a dynamical system with critical behavior; namely, the system becomes unstable when the kinetic matrix of pseudo-first-order reaction becomes negatively defined with a negative eigenvalue giving the rate of exponential (chain) growth of the reactive species.
在低 pH 值（2.5）、空气饱和的水溶液中，当存在 Fe(II) 时，酒石酸的自动氧化表现出明显的自催化行为，具有独特的引发、传播和终止阶段。随着 pH 值的增加，引发阶段加快，而传播阶段缩短并消失。我们表明，传播阶段是通过在引发阶段激活氧气而发生的链式反应，产生过氧化氢。随后的芬顿氧化反应以正反馈的方式再生过氧化氢，是典型的自维持链式反应。这种链式反应的条件与具有临界行为的动力系统相似；即，当拟一级反应的动力学矩阵具有负特征值而变得负定时，系统变得不稳定，给出反应性物质指数（链）增长的速率。
