A structure-reactivity correlation with three slopes in the elimination kinetics of 2-substituted ethyl<i>N</i>,<i>N</i>-dimethylcarbamates in the gas phase
作者:Gabriel Chuchani、Oswaldo Nunñez、Norka Marcano、Suvighey Napolitano、Henry Rodriguez、Marianella Domínguez、Judany Ascanio、Alexandra Rotinov、Rosa M. Domínguez、Armando Herize
DOI:10.1002/poc.341
日期:2001.3
a: the 2-substituted alkyl groups gave a good straight line when log (k/kCH3) vs σ* values (ρ* = − 1.94 ± 0.30, r = 0.977 at 360 °C) were plotted. Slope b: Polar2 substituents gave an approximate straight line with ρ* = − 0.12 ± 0.02, r = 0.936 at 360 °C. Slope c : the correlation of multiple bonded and electron-withdrawing substituents interposed by a methylene group at the 2-position of ethyl N,N-dimethylcarbamate
在269.5–420.2°C的温度范围和24–186 Torr的压力范围内测定了气相中17种2-取代的N,N-二甲基氨基甲酸乙酯的消除动力学。在静态系统中和存在自由基抑制剂的情况下,反应是均相的和单分子的,并且遵循一级速率定律。描述了动力学和热力学参数。除了塔夫脱(Taft)σ*值以外,使用几种结构-反应关系方法无意义。在σ*(CH 3)= 0.00处产生了三个良好的斜率。斜率a:当log(k / k CH 3)与σ*值(ρ* = − 1.94±0.30,r 在360°C时= 0.977)。斜率b:极性2的取代基 在360°C下具有ρ* = − 0.12±0.02,r = 0.936的近似直线。斜率c:在N,N-二甲基氨基甲酸酯的2-位上亚甲基插入的多个键合和吸电子取代基的相关性,得到了非常好的直线,ρ* = 0.49±0.02,r = 0.991在360°C下。在这些关系的基础上提出了机制。取代基苯基(C