Correlation of hydrogen-atom abstraction reaction efficiencies for aryl radicals with their vertical electron affinities and the vertical ionization energies of the hydrogen-atom donors.
Correlation of hydrogen-atom abstraction reaction efficiencies for aryl radicals with their vertical electron affinities and the vertical ionization energies of the hydrogen-atom donors.
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芳基自由基的氢原子夺取反应效率与其垂直电子亲和力和氢原子供体的垂直电离能的相关性。
DOI：
10.1021/ja801707p
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发表时间：
2008-12-31
影响因子：
15
通讯作者：
Kenttaemaa, Hilkka I.
中科院分区：
文献类型：
--
作者：
Jing, Linhong;Nash, John J.;Kenttaemaa, Hilkka I.
利用双池傅立叶变换离子回旋共振质谱仪（FT-ICR）研究了控制芳基自由基对氢原子供体反应性的因素。测量了 23 种结构不同的带正电荷的芳基自由基（包括脱氢苯、脱氢萘、脱氢吡啶和脱氢（异）喹啉）的两种底物（环己烷和异丙醇）的氢原子夺取反应效率。在氢原子夺取反应效率和芳基自由基的（计算的）垂直电子亲和势（EA）之间发现了对数相关性。发现三个芳基与异丙醇计算的过渡态能量与其（计算的）EA 线性相关。在氢原子夺取反应效率和（计算的）反应焓变之间没有发现相关性。对几种不同的氢原子供体与一些选定的芳基自由基反应的反应效率的测量揭示了氢原子夺取反应效率与氢原子供体的垂直电离能（IE）之间的对数相关性，但不是氢原子供体的最低均解X-H（X=重原子）键解离能之间的对数相关性。对 29 种不同芳基自由基和 18 种不同氢原子供体的氢原子夺取反应的检查表明，随着氢原子供体的 IE 和芳基自由基的 EA 之间的差异减小，反应效率增加（对数）。这种依赖性可能是由于随着中性反应物和离子反应物之间的能量差减小而导致过渡态的极化增加以及随之而来的稳定性。因此，芳基自由基的氢原子夺取反应效率可以通过影响芳基自由基的垂直 EA 或氢原子供体的垂直 IE 的结构变化来“调节”。
The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer (FT – ICR). Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropanol, were measured for twenty-three structurally different, positively-charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for three of the aryl radicals with isopropanol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of several different hydrogen-atom donors with a few selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X – H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of twenty-nine different aryl radicals and eighteen different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state as the energy difference between the neutral and ionic reactants decreases. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be “tuned” by structural changes that influence either the vertical EA of the aryl radical or the vertical IE of the hydrogen atom donor.
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影响因子：
4.4
作者：
Becke, AD
通讯作者：
Becke, AD
影响因子：
3.6
作者：
BAKER, AD;ARMEN, GH;GROSSMAN, J
通讯作者：
GROSSMAN, J
影响因子：
7.4
作者：
CHEN, L;WANG, TCL;MARSHALL, AG
通讯作者：
MARSHALL, AG
影响因子：
--
作者：
CHEN, YH;TSCHUIKOWROUX, E
通讯作者：
TSCHUIKOWROUX, E
DOI：
10.1016/0368-2048(74)80083-6
发表时间：
1974-01-01
影响因子：
1.9
作者：
DEBIES, TP;RABALAIS, JW
通讯作者：
RABALAIS, JW