Radical Cations in the OH-Radical-Induced Oxidation of Thiourea and Tetramethylthiourea in Aqueous Solution
作者:Wen-feng Wang、Man Nien Schuchmann、Heinz-Peter Schuchmann、Wolfgang Knolle、Justus von Sonntag、Clemens von Sonntag
DOI:10.1021/ja983275b
日期:1999.1.1
reaction of OH(-) with the dimeric radical cation. The dimeric radical cations of thiourea and tetramethylthiourea are strong oxidants and readily oxidize the superoxide radical (4.5 x 10(9) dm(3) mol(-1) s(-1) for thiourea and 3.8 x 10(9) dm(3) mol(-1) s(-1) for tetramethylthiourea), phenolate ion (3 x 10(8) dm(3) mol(-1) s(-1) for tetramethylthiourea), and even azide ion (4 x 10(6) dm(3) mol(-1) s(-1)
羟基自由基是在硫脲和四甲基硫脲的 N (2) O 饱和水溶液中产生的。OH 自由基与硫脲(四甲基硫脲)反应的速率常数已使用 2-丙醇和 NaN(3) 作为竞争剂确定为 1.2 x 10(10) dm(3) mol(-1) s(- 1) (8.0 x 10(9) dm(3) mol(-1) s(-1))。短暂的诱导期后出现瞬态,并显示明确的吸收光谱,λ(max) = 400 nm (epsilon = 7400 dm(3) mol(-1) cm(-1));四甲基硫脲的λ(max) = 450 nm (epsilon = 6560 dm(3) mol(-1) cm(-1))。使用电导检测表明,在这两种情况下,都会产生 OH(-) 和带正电荷的物质。这些结果表明形成了自由基阳离子。这些 lambda(max) = 400 nm (450 nm) 的中间体不是主要的自由基阳离子,因为吸光度的强度取