The sulfate transfer reaction from dinitrophenyl sulfate to hydroxamate nucleophiles was studied in the presence of several types of aqueous micelles at 30 °C, pH 8–9. The zwitterionic hydroxamate was a nucleophile much better than the anionic hydroxamate in the CTAB micelle. The kinetic behavior of the zwitterionic hydroxamate nucleophile was not straightforward and the reactivity of the nucleophile increased with the increase in the relative concentration of the nucleophile and surfactant. These results in the CTAB micelle was analyzed in terms of the two phase model and the rate enhancement relative to the nonmicellar reaction was attributed to substrate binding in the micellar phase and the micellar activation of the hydroxamate nucleophile. The cleavage of dinitrophenyl sulfate by the micellar zwitterionic nucleophile was faster than that by the nonmicellar hydroxamate and the water cleavage by factors of ca. 104 and more than 107, respectively: the fastest cleavage ever observed at the ambient condition.
在30°C、pH 8-9的条件下,研究了从
二硝基苯磺酸酯向
羟胺亲核试剂的
硫酸根转移反应,研究中使用了多种类型的
水相胶束。与阴离子
羟胺相比,双性离子
羟胺在CTAB胶束中的亲核能力要强得多。双性离子
羟胺亲核试剂的动力学行为并不简单,亲核试剂的反应性随着亲核试剂与表面活性剂的相对浓度增加而增强。CTAB胶束中的这些结果被分析为两相模型,相对于非胶束反应的速率增强归因于底物在胶束相的结合以及胶束对
羟胺亲核试剂的活化。胶束双性离子亲核试剂
对二硝基苯磺酸酯的裂解速度比非胶束
羟胺快约104倍,
水裂解速度则快于107倍:这是在常温条件下观察到的最快裂解速率。