The catalytic effect of catiohic amino micelles on the hydrolysis of substituted phenyl esters
作者:Ch. Rav-Acha、I. Ringel、S. Sarel、J. Katzhendler
DOI:10.1016/s0040-4020(01)81445-9
日期:1988.1
pKo=6.78 respectively. The partition ratio k±/k-a of the zwiterionic tetrahedral intermediate was derived from the experimental data and produced the following correlation: log k±/k-a=-0.92pKo+0.43pKN+2.466. The ester CPNBA exhibited a deuterium isotope effect of 2.1. From product analysis it was concluded that the reaction proceeds via a general base catalysis of aminolysis.
确定了两个氨基阳离子胶束对取代的苯基癸酸酯和正电荷苯甲酸酯(CPNBA)水解的催化作用。胶束催化剂的一般结构为[CH 3(CH 2)3 N(CH 3)2(CH 2)n NH 2 ] Br,其中n = 2(胶束1)。n = 3(胶束2)。动力学遵循表达式:K OBS = K ö + K猫×K个一个/(K一+ H +)+ K ö OH [OH -]。通过将kc OH速率与由非催化胶束中的反应推导的特定碱催化速率进行比较,可以得出结论,kc OH术语主要与由氧离子催化的氨解反应相容。除了非常小的氘同位素效应外,哈米特和布朗斯台德相关性(p = 2.8;β= 1.0)提示kcat与亲核机理相对应。胶束1和2中苯酚酸酯离去基团的log k cat对pKa的布朗斯台德图显示出双相行为。曲线的折断分别发生在pK o= 5.89和pK o= 6.78。分配比k ± / k -a从实验数据得出两性离子四面体