Kinetic Study on S<sub>N</sub>Ar Reactions of 1-(Y-Substituted-phenoxy)-2,4-dinitrobenzenes with Azide Ion: Effect of Changing Nucleophile from Hydroxide to Azide Ion on Reaction Mechanism and Reactivity
作者:Hyeon-Ok Seo、Min-Young Kim、So-Yeop Han、Ik-Hwan Um
DOI:10.1002/bkcs.10333
日期:2015.7
the leaving Y‐substituted‐phenoxy moiety in the transition state. Accordingly, the reactions have been concluded to proceed through a stepwise mechanism, in which expulsion of the leaving group occurs in the rate‐determining step. Comparison of kN3− with the kOH− values reported previously for the corresponding reactions with OH− has revealed that is only 6‐ to 26‐fold less reactive than OH− toward substrates
1-(Y-取代苯氧基)-2,4-二硝基苯(2a-2h)与80 mol%H 2 O / 20 mol%DMSO的S N Ar反应的二级速率常数(k N3-)分光光度法测得的温度为25.0±0.1°C。所述布朗斯台德型情节是线性与β LG = -0.38。与常数相关的哈米特图显示出高度分散的点。与此相反,汤川-津野情节导致具有优异的线性相关ρ Ŷ = 1.02和- [R= 0.51,表明负电荷部分在过渡态的剩下的Y-取代的苯氧基部分的O原子上形成。因此,已经得出反应是通过逐步机制进行的,其中在速率确定步骤中发生离去基团的驱除。比较ķ N3-与ķ OH-值先前用于与OH的相应的反应报告-曾透露,仅比OH 6至26倍的反应性较低的-朝向基板2A-2H,虽然前者是超过11 p ķ一种基本单位比后者少。溶剂化和极化效应已建议负责对显示的异常反应和OH - 。选自OH改变亲核试剂的影响-对进行了详细讨论关于反应机理和反应性。