The Effect of Viscosity on the Coupling and Hydrogen-Abstraction Reaction between Transient and Persistent Radicals?
作者:Xiaopei Li、Tatsuhisa Kato、Yasuyuki Nakamura、Shigeru Yamago
DOI:10.1246/bcsj.20200398
日期:2021.3.15
The effect of viscosity on the radical termination reaction between a transient radical and a persistent radical undergoing a coupling reaction (Coup) or hydrogen abstraction (Abst) was examined. In a non-viscous solvent, such as benzene (bulk viscosity ηbulk < 1 mPa s), all the transient radicals studied exclusively coupled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) with >99% Coup/Abst selectivity
考察了粘度对瞬态自由基与持久性自由基之间进行偶联反应(Coup)或夺氢(Abst)的自由基终止反应的影响。在一个非粘性的溶剂,如苯(体积粘度η散装<1毫帕·秒),所有研究的专门加上2,2,6,6-四甲基哌啶-1-氧基(TEMPO)的瞬态自由基与> 99%政变/ Abst选择性,但当粘度增加时Coup / Abst降低(在25°C [ η体积= 84 mPa s]下,PEG400中为89/11 )。虽然体粘度是预测突然/突然变形的好参数在每种溶剂中的选择性,微粘度是更通用的参数。聚(甲基丙烯酸甲酯)(PMMA)端基比聚苯乙烯(PSt)端基具有更显着的粘度效应,在高粘度介质中(η体积= 3980 mPa ,前者的Coup / Abst比下降至50/50)s),而后者保持较高的Coup / Abst选择性(84/16)。这些结果以及休眠的PMMA-TEMPO物种与PSt-TEMPO物种相比具有较