Rate and equilibrium studies of the reaction of oxyanions with 2-phenyloxazol-5(4H)-one
作者:Edwin Chrystiuk、Adelina Jusoh、Dino Santafianos、Andrew Williams
DOI:10.1039/p29860000163
日期:——
Equilibrium constants for the reaction of phenoxide ions with 2-phenyloxazol-5(4H)-one at 25 °C and 1 M ionic strength obey a Brønsted relationship (log kOH/kArO= log K′=–1.73pKArOH– 15.81) and are not subject to steric effects from ortho-substituents. Both forward and reverse rate parameters exhibit steric effects, and the Brønsted equations for meta- and para-substituted species are log kOH=–0.81
在25°C和1 M离子强度下,酚盐离子与2-苯基恶唑-5(4 H)-one反应的平衡常数服从布朗斯台德关系(log k OH / k ArO = log K '= –1.73p K ArOH – 15.81),并且不受邻位取代基的空间位阻的影响。正向和反向速率参数均显示出空间效应,间位和对位取代物种的Brønsted方程为log k OH = –0.81 p K ArOH + 9.75,log k ArO = 0.95p KArOH – 6.40。在p K ArOH 5-11的区域内,Brønsted线没有中断,这与一个过渡态一致。低碱度的氧阴离子存在向上偏差(p K XOH <5);这些氧阴离子之一,甜菜碱,由于其与恶唑酮的反应大于2,具有溶剂性氘氧化同位素作用,这与攻击这些物质的一般基本机理相符。酚酸根阴离子的亲核攻击结果与羰基的协同位移一致。