在几种溶剂中研究了由1,1-二甲基-7,7-二苯基-2-甲磺酰氧基-6-庚烯基甲磺酸酯杂化形成的自由基阳离子。计算结果表明,最初形成的无环自由基阳离子是一种共振杂合体,在1,1-二苯基-7-甲基-1,6-辛二烯的两个双键中均带有部分正电荷(10)。硫酚捕集用作动力学测定的竞争反应。无环自由基阳离子与环状二歧自由基阳离子迅速平衡,并且硫酚捕集得到无环产物10和环状产物,主要是反式-1-(二苯基甲基)-2-(1-甲基乙烯基)环戊烷(11)。在环境温度下环化的速率常数为k=(0.5-2)×10 10 s -1,开环用的是k=(1.5-9)×10 10 s -1。在几种溶剂中进行的激光闪光光解研究表明,相对缓慢的过程(k =(2.5-260)×10 5 s -1),涉及限制自由基阳离子的限速捕集反应。在氟代醇的混合物中,R f CH 2三氟甲基苯中的OH(可变温度研究)显示出较小的活化能,在某
Phenanthrene-sensitized photoreaction of 1,1-diphenylethene (DPE) derivatives and 1,4-dicyanobenzene (DCNB) in benzene leads to a novel intermolecular cycloaddition to give isoquinoline derivatives as a novel synthetic method. The feasibility of this reaction was dependent upon the side chain structure of DPE derivatives, which would regulate the stability of radical cation DPE+· in a highly polar
Radical Heterolysis Reactions. Dynamics of Formation, Collapse, and Solvation of Ion Pairs Determined by a Competition Kinetic Method
作者:John H. Horner、Mukul Lal、Martin Newcomb
DOI:10.1021/ol062242v
日期:2006.11.1
The kinetics of radicalheterolysis reactions, including rate constants for radical cation-anion contact ion pair formation, collapse of the contact pair back to the parent radical, and separation of the contact pair to a solvent-separated ion pair or free ions were obtained in several solvents for a beta-mesyloxy radical. Rate constants were determined from indirect kinetic studies using thiophenol