Mechanism and structure-reactivity correlation in the homogeneous, unimolecular elimination kinetics of 2-substituted ethyl methylcarbonates in the gas phase
作者:Gabriel Chuchani、Edgar Marquez、Armando Herize、Rosa María Domínguez、María Tosta、Doris Brusco
DOI:10.1002/poc.665
日期:2003.11
The gas-phase elimination kinetics of 2-substituted ethyl methylcarbonates were determined in a static reaction system over the temperature range of 323–435°C and pressure range 28.5–242 Torr. The reactions are homogeneous, unimolecular and follow a first-order rate law. The kinetic and thermodynamic parameters are reported. The 2-substituents of the ethyl methylcarbonate (CH3OCOOCH2CH2Z, Z=substituent)
在静态反应系统中,在323–435°C的温度范围和28.5–242托的压力范围内,测定了2-取代的乙基碳酸甲酯的气相消除动力学。反应是均相的,单分子的并且遵循一阶速率定律。报道了动力学和热力学参数。使用塔夫脱-托普索姆法时,碳酸甲乙酯的2个取代基(CH 3 OCOOCH 2 CH 2 Z,Z =取代基)呈现近似线性相关,log(k Z / k H)=-(0.57±0.19)σ α +(1.34±0.49)σ - [R -( - [R= 0.9256;SD = 0.16)在400°C下。该结果暗示消除过程对空间因素敏感,而电子效应并不重要。然而,该共振系数具有用于C的β氢的有利抽象影响最大β由氧羰基-H键。因为ρ α是显著,获得具有Hancock的立体参数碳酸酯的烷基取代基的一个良好的相关性:日志(ķ - [R / ķ ħ)与Ë小号Ç为CH 3 OCOOCH 2 CH 2 - [R在400℃下,R