Kinetics and Mechanism of the Aminolysis of Aryl <i>N</i>-Ethyl Thiocarbamates in Acetonitrile
作者:Hyuck Keun Oh、Jie Eun Park、Dae Dong Sung、Ikchoon Lee
DOI:10.1021/jo0484676
日期:2004.12.1
The aminolysis of aryl N-ethyl thiocarbamates (EtNHC(O)SC6H4Z) with benzylamines (XC6H4CN2NH2) in acetonitrile at 30.0 °C is investigated. The rates are faster than the corresponding values for aryl N-phenyl thiocarbamates (PhNHC(O)SC6H4Z), reflecting a stronger push to expel the leaving group by EtNH than the PhNH nonleaving group in a concerted process. The negative ρXZ (−0.86) and failure of the
在30.0°C下研究了芳基N-乙基硫代氨基甲酸酯(EtNHC(O)SC 6 H 4 Z)与苄胺(XC 6 H 4 CN 2 NH 2)的氨解作用。该速率比芳基N-苯基硫代氨基甲酸酯(PhNHC(O)SC 6 H 4 Z)的相应值快,反映出在协同过程中,EtNH推动离去基团的能力比PhNH非离去基团强。负ρXZ(-0.86)和发现的反应性-选择性原则的失败与一致的机制是一致的。涉及氘化的亲核试剂动力学同位素效应(ķ ħ / ķ d = 1.5-1.7)和低Δ ħ ⧧与大的负Δ小号⧧数值表明氢键环状过渡状态。