Estimation of standard reduction potentials of alkyl radicals involved in atom transfer radical polymerization
Estimation of standard reduction potentials of alkyl radicals involved in atom transfer radical polymerization
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DOI：
10.1016/j.electacta.2010.02.099
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发表时间：
2010-11-30
影响因子：
6.6
通讯作者：
Gennaro, Armando
中科院分区：
文献类型：
--
作者：
Bortolamei, Nicola;Isse, Abdirisak A.;Gennaro, Armando
用间接电化学方法研究了在原子转移自由基聚合中起重要作用的烷基自由基的氧化还原性质，这些烷基自由基既可作为引发剂，也可作为增长自由基链的模拟物。产生一个中间自由基（R），该自由基通过自由基偶联或电子转移与D（-）进一步反应。研究这些反应之间的竞争（取决于E度（D/D）（-）），可以确定R的标准还原电位以及自交换重组能λ（R）（/R-）CH_2CN、CH_2CO_2 Et和CH（CH_3）CO_2 Me的标准还原电位分别为-0.72 +/-0.06 ~ 0.63 +/-0.07和-0.66 +/-0.07Vvs SCE。（从122到164 kJ mol（-1）），表明结构的显着变化伴随着电子转移到R（C）2010 Elsevier Ltd版权所有
The redox properties of some alkyl radicals which are important in atom transfer radical polymerization both as initiators and mimics of the propagating radical chains have been investigated in CH3CN by an indirect electrochemical method based on homogeneous redox catalysis involving alkyl halides (RX) and electrogenerated aromatic or heteroaromatic radical anions (D (-)) Dissociative electron transfer between RX and D (-) yields an intermediate radical (R) which further reacts with D (-) either by radical coupling or by electron transfer Examination of the competition between these reactions which depends on E degrees(D/D) (-) allows determination of the standard reduction potential of R as well as the self-exchange reorganization energy lambda(R) (/R-) The standard reduction potentials obtained for the radicals CH2CN CH2CO2Et and CH(CH3)CO2Me are -0 72 +/- 0 06 -0 63 +/- 0 07 and -0 66 +/- 0 07V vs SCE respectively Quite high values of lambda(R) (/R-) (from 122 to 164 kJ mol(-1)) were found for all radicals indicating that a significant change of structure accompanies electron transfer to R (C) 2010 Elsevier Ltd All rights reserved