Kinetic study of the phthalimide N-oxyl (PINO) radical in acetic acid.: Hydrogen abstraction from C-H bonds and evaluation of O-H bond dissociation energy of N-hydroxyphthalimide
Kinetic study of the phthalimide N-oxyl (PINO) radical in acetic acid.: Hydrogen abstraction from C-H bonds and evaluation of O-H bond dissociation energy of N-hydroxyphthalimide
复制标题
DOI：
10.1021/jp0276193
复制
发表时间：
2003-05-29
影响因子：
2.9
通讯作者：
Espenson, JH
中科院分区：
文献类型：
--
作者：
Koshino, N;Cai, Y;Espenson, JH
研究了邻苯二甲酰亚胺N-氧自由基（PINO）与几种具有不同C-H键离解能（BDEs）的碳氢化合物在25 ℃ HCAc中的反应。Evans-Polanyi曲线的斜率为0.38，这表明反应是轻度放热或几乎热中性的。这一发现得到了N-羟基邻苯二甲酰亚胺（NHPI）的O-H BDE的支持，375 +/- 10 kJ mol（-1），通过热力学循环获得。所观察到的动力学同位素效应（KIEs）与反应自由能的变化有关，可以用Marcus型方程解释。PINO自由基反应与二溴自由基的类似氢原子提取反应的比较表明，HBr 2.反应比PINO自由基反应放热更大。这一因素被提出来解释不同的KIE。
The reactions of the plithalimide N-oxyl (PINO) radical with several hydrocarbons having different C-H bond dissociation energies (BDEs) were investigated in HCAc at 25 degreesC. The slope of the Evans-Polanyi plot is 0.38, which indicates that the reactions are mildly exothermic or almost thermoneutral. This finding is supported by the O-H BDE of N-hydroxyphthalimide (NHPI), 375 +/- 10 kJ mol(-1), obtained by means of a thermodynamic cycle. The observed kinetic isotope effects (KIEs) are related to the reaction free-energy changes, which can be explained by a Marcus-type equation. The comparison of the PINO radical reactions with analogous hydrogen atom abstraction reactions of the dibromide radical implies that HBr2.reactions are more exothermic than the PINO radical reactions. This factor is put forth to explain the different KIEs.