Kinetic Solvent Effects on Hydrogen Abstraction Reactions from Carbon by the Cumyloxyl Radical. The Importance of Solvent Hydrogen-Bond Interactions with the Substrate and the Abstracting Radical
作者:Michela Salamone、Ilaria Giammarioli、Massimo Bietti
DOI:10.1021/jo200660d
日期:2011.6.3
kinetic solvent effect for hydrogen atom abstraction reactions from hydrocarbons by alkoxyl radicals and indicates that strong HBD solvents influence the hydrogen abstraction reactivity of CumO•. With PA and DMPA a significant decrease in kH has been observed on going from benzene and PhCl to MeOH and TFE, indicative of hydrogen-bond interactions between the carbonyl lone pair and the solvent in the
在不同的溶剂(苯,PhCl,MeCN,t- BuOH,MeOH中)进行了枯基氧基(CumO •)从丙醛(PA)和2,2-二甲基丙醛(DMPA)夺取氢原子反应的动力学研究。和TFE)。在MeCN中已经研究了苄氧基基团(BnO •)的相应反应。还已经在TFE溶液中研究了CumO •与1,4-环己二烯(CHD)的反应。使用CHD时,速率常数(k H)在从苯,PhCl和MeCN到TFE的过程中被观察到。这代表了对烃类通过烷氧基从氢原子提取反应中产生相当大的动力学溶剂作用的首次观察,并表明强HBD溶剂会影响CumO •的氢提取反应性。使用PA和DMPA时,从苯和PhCl到MeOH和TFE的k H显着降低,这表明在过渡态下,羰基孤对与溶剂之间的氢键相互作用。相似k H醛在MeOH和TFE中的反应所观察到的数值表明,后者溶剂与底物和处于过渡态的自由基之间存在差异的氢键相互作用。观察到的CumO •和BnO