Baranyi Nóra, Csekő György, Valkai László, Xu Li, Horváth Attila K
Department of Inorganic Chemistry, University of Pécs , Ifjúság útja 6, H-7624 Pécs, Hungary.
Inorg Chem. 2016 Mar 7;55(5):2436-40. doi: 10.1021/acs.inorgchem.5b02836. Epub 2016 Feb 5.
The chlorite-periodate reaction has been studied spectrophotometrically in acidic medium at 25.0 ± 0.1 °C, monitoring the absorbance at 400 nm in acetate/acetic acid buffer at constant ionic strength (I = 0.5 M). We have shown that periodate was exclusively reduced to iodate, but chlorite ion was oxidized to chlorate and chlorine dioxide via branching pathways. The stoichiometry of the reaction can be described as a linear combination of two limiting stoichiometries under our experimental conditions. Detailed initial rate studies have clearly revealed that the formal kinetic orders of hydrogen ion, chlorite ion, and periodate ion are all strictly one, establishing an empirical rate law to be d[ClO2]/dt = kobs[ClO2(-)][IO4(-)][H(+)], where the apparent rate coefficient (kobs) was found to be 70 ± 13 M(-2) s(-1). On the basis of the experiments, a simple four-step kinetic model with three fitted kinetic parameters is proposed by nonlinear parameter estimation. The reaction was found to proceed via a parallel oxygen transfer reaction leading to the exclusive formation of chlorate and iodate as well as via the formation of a short-lived key intermediate OClOIO3 followed by its further transformations by a sequence of branching pathways.
在25.0±0.1°C的酸性介质中，采用分光光度法研究了亚氯酸盐-高碘酸盐反应，在恒定离子强度（I = 0.5 M）的醋酸盐/醋酸缓冲溶液中监测400 nm处的吸光度。我们已经表明，高碘酸盐仅被还原为碘酸盐，但亚氯酸根离子通过分支途径被氧化为氯酸盐和二氧化氯。在我们的实验条件下，该反应的化学计量关系可以描述为两种极限化学计量关系的线性组合。详细的初始速率研究清楚地表明，氢离子、亚氯酸根离子和高碘酸根离子的形式动力学级数均严格为1，建立了经验速率定律d[ClO₂]/dt = kobs[ClO₂⁻][IO₄⁻][H⁺]，其中表观速率系数（kobs）为70±13 M⁻² s⁻¹。基于这些实验，通过非线性参数估计提出了一个具有三个拟合动力学参数的简单四步动力学模型。发现该反应通过平行的氧转移反应进行，导致仅生成氯酸盐和碘酸盐，以及通过形成一个短寿命的关键中间体OClOIO₃，随后通过一系列分支途径对其进行进一步转化。
