Oxyhalogen–sulfur chemistry — Kinetics and mechanism of the bromate oxidation of cysteamine
作者:Moshood K Morakinyo、Edward Chikwana、Reuben H Simoyi
DOI:10.1139/v08-031
日期:2008.5.1
The kinetics and mechanism of the oxidation of the biologically important molecule, cysteamine, by acidic bromate and molecular bromine have been studied. In excess acidic bromate conditions, cysteamine is oxidized to N- brominated derivatives, and in excess cysteamine the oxidation product is taurine according to the following stoichiometry: BrO3 - +H 2NCH2CH2SH H2NCH2CH2SO3 H+B r - . There is quantitative
研究了酸性溴酸盐和分子溴对生物学上重要的分子半胱胺进行氧化的动力学和机制。在过量的酸性溴酸盐条件下,半胱胺被氧化成N-溴化衍生物,并且在过量的半胱胺中,根据以下化学计量,氧化产物是牛磺酸:BrO3 - +H 2NCH2CH2SH H2NCH2CH2SO3 H+B r - 。在 N-溴化开始之前,牛磺酸会定量形成。过量的溴水溶液氧化半胱胺生成二溴牛磺酸: 5Br2 +H 2NCH2CH2 SH +3 H2O Br2NCH2CH2SO3H + 8Br - +8 H + ,而过量的半胱胺条件生成单溴牛磺酸。溴水溶液对半胱胺的氧化一直受到有效的扩散控制,直至形成单溴牛磺酸。二溴牛磺酸的进一步形成取决于酸浓度,在高酸性条件下抑制进一步反应形成二溴牛磺酸。牛磺酸的 N-溴化衍生物的形成是可逆的,牛磺酸在还原剂如碘化物的存在下再生。这一特性使牛磺酸能够在生理环境中减轻次溴酸的毒性。