Absolute Kinetics of Aminium Radical Reactions with Olefins in Acetonitrile Solution<sup>1</sup>
作者:Brian D. Wagner、Géraldine Ruel、Janusz Lusztyk
DOI:10.1021/ja950133y
日期:1996.1.1
of N-nitrosamines in acidic acetonitrile produces aminium radical cations via protonation of the initially-formed aminyl radicals. The kinetics of these species can be monitored by transient UV spectroscopy via their absorption band which is found at ca. 300 nm in the case of the piperidinium radical, for example. By measuring the aminium radicals' lifetimes as a function of the concentration of added
N-亚硝胺在酸性乙腈中的光解通过最初形成的氨基自由基的质子化产生氨基自由基阳离子。这些物种的动力学可以通过瞬态紫外光谱法通过它们的吸收带进行监测,该吸收带在约 例如,在哌啶自由基的情况下为 300 nm。通过测量作为加入烯烃浓度的函数的胺自由基的寿命,获得了加成反应的双分子速率常数的绝对值。在哌啶自由基的情况下,这些速率常数从丙烯腈的 <1 × 106 M-1 s-1 到 1,1-二苯基乙烯的 1.1 ± 0.1 × 109 M-1 s-1 变化,并且通常随着电离电位的降低而增加烯烃,从而证实了哌啶鎓自由基的亲电性质。二乙胺自由基类似反应的速率常数小 1.5-25 倍,表明空间因素在胺自由基加成到烯烃中的重要性。利率不变...