Oxyhalogen–sulfur chemistry: kinetics and mechanism of oxidation of formamidine disulfide by acidic bromate
作者:Nicholas Madhiri、Rotimi Olojo、Reuben H. Simoyi
DOI:10.1039/b305353a
日期:——
The kinetics and mechanism of the oxidation of formamidine disulfide, FDS, a dimer and major metabolite of thiourea, by bromate have been studied in acidic media. In excess bromate conditions the reaction displays an induction period before formation of bromine. The stoichiometry of the reaction is: 7BrO3− + 3[(H2N(HN)CS–]2 + 9H2O → 6NH2CONH2 + 6SO42− + 7Br− + 12H+ (A). In excess oxidant conditions
已经研究了溴酸盐在酸性介质中氧化二硫化甲脒(FDS,一种二聚体和硫脲的主要代谢物)的动力学和机理。在过量溴酸盐条件下,反应在溴形成之前显示出诱导期。反应的化学计量为:7BrO3- + 3[(H2N(HN)CS-]2 + 9H2O → 6NH2CONH2 + 6SO42- + 7Br- + 12H+ (A)。然而,在过量氧化剂条件下,溴化物在反应 A 中形成与溴酸盐反应生成溴,最终化学计量为: 14BrO3− + 5[(H2N(HN)CS–]2 + 8H2O → 10NH2CONH2 + 10SO42− + 7Br2 + 6H+ (B)。溴和 FDS 的直接反应也是经研究,其化学计量为:7Br2 + [(H2N(HN)CS–]2 + 10H2O → 2NH2CONH2 + 2SO42- + 14Br- + 18H+ (C)。反应 A 的总速率,由 FDS 的消耗速率测量,是酸浓度的二阶,表明控制活性物质