log (A/M−1 s−1)=7.9±0.5. The rate constants of the secondary 1-[(tert-butoxy)carbonyl]ethyl radical are close to the geometric mean of those of the related primary [(tert-butoxy)carbonyl]methyl and the tertiary 2-(methoxycarbonyl)propan-2-yl radicals. The activation energies for addition of these three carboxy-substituted alkyl radicals are mainly governed by the addition enthalpy but are also substantially
报告了将 1-[(叔丁氧基)羰基]乙基自由基 (MeC.HCO2Me3) 加成到
乙腈中的几种单或 1,1-二取代烯烃的绝对速率常数和它们的一些 Arrhenius 参数,按时间计算-分辨电子自旋共振光谱。在 295 K 时,速率常数范围从 470 M-1 s-1(丁-1-烯)到 2.4⋅105 M-1 s-1(1,1-二苯基
乙烯),实验活化能范围从 26.8 kJ/ mol(丁-1-烯)至14.7 kJ/mol(
苯乙烯),频率因子服从平均log(A/M-1 s-1)=7.9±0.5。仲 1-[(叔丁氧基)羰基]乙基自由基的速率常数接近相关伯 [(叔丁氧基)羰基]甲基和叔 2-(甲氧基羰基)
丙烷-2 的几何平均值-yl 自由基。加成这三个羧基取代的烷基自由基的活化能主要受加成焓控制,但也因两亲极性效应而显着降低。结果支持先前推导的预测分析,并讨论了与
丙烯酸酯聚合速率常数的关系。