Department of Inorganic Chemistry, University of Pécs, Ifjúság u. 6, Pécs, H-7624, Hungary.
Phys Chem Chem Phys. 2010 Jul 7;12(25):6742-9. doi: 10.1039/b921858k. Epub 2010 Apr 29.
The tetrathionate-periodate reaction has been studied in presence of acetate-acetic acid buffer at T = 25 +/- 0.1 degrees C and at I = 0.5 M ionic strength by a conventional diode array spectrophotometer. The stoichiometry of the reaction was found to be S(4)O + 7IO + 3H(2)O --> 4SO + 7IO + 6H(+). The profile of the measured absorbance-time curve is sigmoidal, having extremely long induction period that may be inferred as a classical type of autocatalysis, but surprisingly none of the products were proven to catalyze the reaction. Initial addition of micro amounts of iodine or iodide ion, however, strongly accelerates the reaction indicating that they are very efficient catalysts of the reaction. Moreover, it is also shown that the analyzing light beam has a great impact on the length of the induction period that questions the existence of the thermal reaction between tetrathionate and periodate. A 9-step kinetic model is presented and discussed that accurately takes the most important feature of the reaction into account.
在 T = 25 ± 0.1°C 和 I = 0.5 M 离子强度下，使用传统的二极管阵列分光光度计在醋酸-乙酸盐缓冲液中研究了连四硫酸盐-高碘酸盐反应。发现该反应的化学计量比为 S(4)O + 7IO + 3H(2)O --> 4SO + 7IO + 6H(+)。测量的吸光度-时间曲线呈钟形，具有非常长的诱导期，可以推断为经典类型的自动催化，但令人惊讶的是，没有一种产物被证明能催化反应。然而，碘或碘化物离子的初始微量添加强烈地加速了反应，表明它们是该反应的非常有效的催化剂。此外，还表明分析光束对诱导期的长度有很大的影响，这质疑了连四硫酸盐和高碘酸盐之间的热反应的存在。提出并讨论了一个 9 步动力学模型，该模型准确地考虑了反应的最重要特征。
