Kinetic study on aminolysis of aryl X-substituted-cinnamates in acetonitrile: differential medium effect determines reactivity and reaction mechanism
作者:Ik-Hwan Um、Ae-Ri Bae、Julian M. Dust
DOI:10.1139/cjc-2018-0310
日期:2019.1
A kinetic study on nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted-cinnamates (1a–1f) and Y-substituted-phenyl cinnamates (2a–2g) with a series of alicyclic secondary amines in MeCN at 25.0 ± 0.1 °C is reported. The Bronsted-type plots for the reactions of 1a–1f are linear with βnuc = 0.47∼0.50, indicating that the bond formation between the amine nucleophile and the electrophilic
2,4-二硝基苯基X-取代肉桂酸酯(1a-1f)和Y-取代-苯基肉桂酸酯(2a-2g)与一系列脂环族仲胺在MeCN中25.0±0.1°C的亲核取代反应动力学研究被报道。1a-1f 反应的布朗斯台德型曲线是线性的,βnuc = 0.47∼0.50,表明胺亲核试剂和亲电子中心之间的键形成在过渡态略微提前。2a-2g 与哌啶反应的 Bronsted 型图也是线性的,βlg = –0.66,这是先前报道的反应通过协同机制进行的典型 βlg 值。此外,与 σ– 常数相关的哈米特图比与 σo 常数相关的线性关系好得多,这意味着离去基团的排出在速率决定步骤 (RDS) 中进行。因此,反应被总结为通过协同机制进行。1a-1f 反应的哈米特图包括...