Do the terms "% ee" and "% de" make sense as expressions of stereoisomer composition or stereoselectivity?
Do the terms "% ee" and "% de" make sense as expressions of stereoisomer composition or stereoselectivity?
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DOI：
10.1021/jo052554w
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发表时间：
2006-03-17
影响因子：
3.6
通讯作者：
Gawley, RE
中科院分区：
文献类型：
--
作者：
Gawley, RE
对映体过量（ee）最初被定义为描述对映体组成的术语，并等同于光学纯度。最近，ee和它的表弟de（非对映异构体过量）已被（不适当地）用于定量立体选择性。数量ee已用于描述动力学分辨率等过程的方程中，但这些方程不必要地复杂，因为它是对映体比，而不是对映体过量，直接反映相对速率。本文对ee作为对映体组成和对映体选择性表达式的发展进行了历史总结，并给出了新的方程和图表，定义和说明了立体选择性因子、s、动力学分辨率与转化率的关系，以及催化剂和产物对映体组成的线性关系。给出了非线性效应与对映异构体组成关系的新图，并讨论和说明了正非线性效应的卡根放大指数。提出了ee和de作为立体异构体组成和立体选择性描述符的不连续性。
Enantiomeric excess (ee) was originally defined as a term to describe enantiomeric composition and was equated with optical purity. More recently, ee and its Cousin de (diastereomeric excess) have been used (inappropriately) to quantitate stereoselectivity. The quantity ee has been used in equations describing processes Such as kinetic resolutions, but these equations are unnecessarily complex because it is enantiomer ratio, not enantiomeric excess, that directly reflects relative rates. A historical summary of: the development of ee as an expression of enantiomer composition and enantioselectivity is presented, along with new equations and figures defining and illustrating the stereoselectivity factor, s, kinetic resolutions versus % conversion, and linear correlations of enantiomer composition of catalysts and products. New figures illustrating nonlinear effects versus enaniomer composition are presented, and Kagan's index of amplification for positive nonlinear effects is discussed and illustrated. A case is made for the discontinuance of ee and de as descriptors of stereoisomer composition and stereoselectivity.