Reduction Potentials and Kinetics of Electron Transfer Reactions of Phenylthiyl Radicals: Comparisons with Phenoxyl Radicals
作者:D. A. Armstrong、Qun Sun、R. H. Schuler
DOI:10.1021/jp960165n
日期:1996.1.1
The reduction potentials relative to the standard hydrogen electrode (SHE) for a number of para-substituted phenylthiyl radicals (E°(p-XC6H4S•/p-XC6H4S-)) have been derived from pulse radiolytic studies of electron transfer equilibria which compare their values to those of radicals of known reduction potentials. A ladder combining the reduction potentials for both phenylthiyl and phenoxyl radicals has
相对于为多个对位取代phenylthiyl自由基(标准氢电极(SHE)还原电位ë °(p -XC 6 ħ 4小号• / p -XC 6 ħ 4小号- ))已经被从脉冲辐解衍生研究电子转移平衡,将其值与已知还原电位的自由基的值进行比较。建立了结合了苯基硫基和苯氧基自由基还原电位的阶梯。这些还原电位已被证明是自洽的,并且介于p的还原电位之间-苯并半醌基阴离子为0.02 V,苯氧基为0.79V。还原电位随着对位取代基的给电子力的增加而降低。然而,对苯硫基自由基的取代作用比对它们的氧类似物的作用要弱得多。这些观察结果表明,硫原子与芳环系统之间的电子相互作用远小于氧原子所发生的电子相互作用。用马库斯理论检验电子传输速率表明,p -XC 6 H 4 O •和p -XC 6 H 4 S •的重组能自由基同样受H,CH 3和CH 3 O取代的影响。然而,重组能大幅提高用于h 2 N和O -位取代基具有其效果是为要少得多p