Kinetics and Mechanism of the Photoinitiated Autoxidation of Sulfur(IV) in the Presence of Iodide Ion

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• 作者：Ildik&oacute ; Kerezsi ; Gá ; bor Lente ; Istvá ; n Fá ; biá ; n
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：May 14, 2007
• 年：2007
• 卷：46
• 期：10
• 页码：4230 - 4238
• 全文大小：92K
• 年卷期：v.46,no.10(May 14, 2007)
• ISSN：1520-510X

文摘

The kinetics and mechanism of the photoinitiated and iodide ion-catalyzed aqueous autoxidation of sulfur(IV) hasbeen studied in a diode-array spectrophotometer using the same light beam for excitation and detection. Lightabsorption of both the iodide ion and sulfur(IV) contribute to the initiation of a highly efficient radical chain reaction,the overall rate of which depends on the reactant and catalyst concentrations, the pH, and the light intensity in acomplex manner. To interpret all the experimental findings, an elaborate scheme is proposed, in which the chaincarriers are SO₃^-, SO₄^-, SO₅^-, I, and I₂^-. There are three termination steps, each of them is second-order withrespect to the chain carriers. Model calculations and nonlinear fitting have been used to show that the proposedscheme gives an excellent quantitative interpretation of the experimental results.