Absolute Rate Constants for the Addition of Cyanomethyl (·CH<sub>2</sub>CN) and (<i>tert</i>-Butoxy)carbonylmethyl (·CH<sub>2</sub>CO<sub>2</sub>C(CH<sub>3</sub>)<sub>3</sub>) radicals to alkenes in solution
作者:Jie Qiang Wu、Ivan Beranek、Hanns Fischer
DOI:10.1002/hlca.19950780118
日期:1995.2.8
Absolute rate constants and their temperature dependence were determined by time-resolved electron spin resonance for the addition of the radicals ·CH2CN and ·CH2CO2C(CH3)3 to a variety of mono- and 1,1-disubstituted and to selected 1,2- and trisubstituted alkenes in acetonitrile solution. To alkenes CH2CXY, ·CH2CN adds at the unsubstituted C-atom with rate constants ranging from 3.3·103M−1S−1 (ethene)
通过时间分辨电子自旋共振确定绝对速率常数及其温度依赖性,方法是将自由基·CH 2 CN和·CH 2 CO 2 C(CH 3)3添加到各种单取代和1,1-二取代基中并在乙腈溶液中选择1,2-和三取代的烯烃。·CH 2 CN在烯烃CH 2 CXY处以未取代的C原子加成,其速率常数范围为3.3·10 3 M -1 S -1(乙烯)至2.4·10 6 M -1 S -1(1,1-二苯基乙烯)在278 K,并且频率因子在log的窄范围内(A / M -1 S -1)= 8.7±0.3。·CH 2 CO 2 C(CH 3)3具有非常相似的反应性,在296 K时的速率常数为1.1·10 4 M -1 S -1(乙烯)至10 7 M -1 S -1(1,1 -二苯乙烯)和频率因子log(A / M -1 S -1)= 8.4±0.1。对于两个自由基,速率常数和添加到CH 2中的活化能CXY与总反应焓密切相