The Effects of Ring Substituents and Leaving Groups on the Kinetics of SNAr Reactions of 1-Halogeno- and 1-Phenoxy-nitrobenzenes with Aliphatic Amines in Acetonitrile
作者:Michael R. Crampton、Thomas A. Emokpae、Chukwuemeka Isanbor
DOI:10.1002/ejoc.200600968
日期:2007.3
attack although this may be mediated by reduced steric congestion around the reaction centre. Specific steric effects, leading to rate-retardation, is noted for the ortho-CF3 group. The 1-phenoxy compounds are subject to base catalysis and values of kAm/k–1 are reduced relative to more strongly activated compounds. This is likely to reflect increases in values of k–1 coupled with decreases in values of
报告了一系列 1-氯-、1-氟-和 1-苯氧基-硝基苯的反应速率常数,这些苯由 CF3 或 CN 基团或环氮与正丁胺、吡咯烷或哌啶在乙腈中活化。将结果与先前报告的更强环活化化合物的结果进行比较。环活化的减少导致亲核攻击的 k1 值降低,尽管这可能是通过减少反应中心周围的空间拥挤来介导的。注意到邻位 CF3 组的特定空间效应导致速率延迟。1-苯氧基化合物受碱催化作用,相对于活性更强的化合物,kAm/k–1 值降低。这可能反映了 k-1 值的增加以及 kAm 值的降低,因为从两性离子中间体到催化胺的质子转移在热力学上变得不太有利。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)