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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >S-Oxygenation of thiocarbamides IV: Kinetics of oxidation of tetramethylthiourea by aqueous bromine and acidic bromate
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S-Oxygenation of thiocarbamides IV: Kinetics of oxidation of tetramethylthiourea by aqueous bromine and acidic bromate

机译：硫脲的S-氧合IV：含水溴和酸性溴酸盐氧化四甲基硫脲的动力学

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摘要

The kinetics and mechanism of oxidation of tetramethylthiourea (TTTU) by bromine and acidic bromate has been studied in aqueous media. The kinetics of reaction of bromate with TTTU was characterized by an induction period followed by formation of bromine. The reaction stoichiometry was determined to be 4BrO_3~- + 3(R)_2C=S + 3H_2O → 4Br~- + 3(R)_2C=O + 3SO_4~(2-) + 6H ~+. For the reaction of TTTU with bromine, a 4:1 stoichiometric ratio of bromine to TTTU was obtained with 4Br_2 + (R)2C=S + 5H_2O → 8Br~- + SO_4~(2-) + (R) _2C=O + 10H~+. The oxidation pathway went through the formation of tetramethythiourea sulfenic acid as evidenced by the electrospray ionization mass spectrum of the dynamic reaction solution. This S-oxide was then oxidized to produce tetramethylurea and sulfate as final products of reaction. There was no evidence for the formation of the sulfinic and sulfonic acids in the oxidation pathway. This implicates the sulfoxylate anion as a precursor to formation of sulfate. In aerobic conditions, this anion can unleash a series of genotoxic reactive oxygen species which can explain TTTU's observed toxicity. A bimolecular rate constant of 5.33 ± 0.32 M~(-1) s~(-1) for the direct reaction of TTTU with bromine was obtained.
机译：在水性介质中研究了溴和酸性溴酸盐氧化四甲基硫脲（TTTU）的动力学和机理。溴酸盐与TTTU的反应动力学的特征在于诱导期，然后形成溴。反应化学计量确定为4BrO 3-+ 3（R）_2C = S + 3H_2O→4Br I- + 3（R）_2C = O + 3SO_4〜（2-）+ 6H〜+。对于TTTU与溴的反应，使用4Br_2 +（R）2C = S + 5H_2O→8Br〜-+ SO_4〜（2-）+（R）_2C = O +获得溴与TTTU的化学计量比为4：1 10H〜+。动态反应溶液的电喷雾电离质谱表明，氧化途径经历了四甲基硫脲亚磺酸的形成。然后将该S-氧化物氧化以产生四甲基脲和硫酸盐作为反应的最终产物。没有证据表明在氧化途径中会形成亚磺酸和磺酸。这暗示了亚硫酸根阴离子作为形成硫酸盐的前体。在有氧条件下，该阴离子可以释放出一系列具有遗传毒性的活性氧，这可以解释TTTU观察到的毒性。得到TTTU与溴直接反应的双分子速率常数为5.33±0.32 M〜（-1）s〜（-1）。

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