期刊
TETRAHEDRON-ASYMMETRY
卷 28, 期 11, 页码 1557-1561出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tetasy.2017.09.006
关键词
-
资金
- Robert A. Welch foundation [Y-0026]
- French National Center for Scientific Research [ISA-CNRS-UMR5280]
Many biaryl compounds possess atropisomerism due to the steric hindrance of substituents at the orthoposition of the two aromatic moieties. Upon heating, atropisomers may have enough energy to surpass the rotational energy barrier and racemize. The thermal stability of five atropisomers was studied using chiral chromatography by following the change in enantiomeric excess ratio at different temperatures. The first order racemization reaction rate was obtained at a given temperature as the slope of the change in enantiomeric excess ratio versus time. For each atropisomer, the racemization rates at different temperatures led to the value of the rotational energy barrier for racemization, Delta G(double dagger), and to the racemization half lifetime, t(1/2), indicating the atropisomer thermal stability. Binaphthol started to racemize significantly at temperature of 190 degrees C and above while binaphthyldiamine was much more stable showing little or very minor racemization up to 210 degrees C. A chloro-substituted phenylamino-naphthol was very sensitive to thermal racemization starting at a low 40 degrees C. (C) 2017 Published by Elsevier Ltd.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据