Difference Between Regioselectivity and Stereoselectivity

Thekey differencebetween regioselectivity and stereoselectivity is thatthe regioselectivity refers to the formation of one positional isomer over another. Meanwhile, stereoselectivity refers to the formation of onestereoisomer在另一个。

The terms regioselectivity and stereoselectivity are very important in organicsynthesis。这些术语描述了化学反应的最终产物的结构。研究区域选择性的化学分支称为区域化学，而研究立体选择性的化学分支称为立体化学。

内容

1.Overview and Key Difference
2.What is Regioselectivity
3.What is Stereoselectivity
4.Side by Side Comparison – Regioselectivity vs Stereoselectivity in Tabular Form
5.概括

什么是区域选择性？

Regioselectivity refers to the making or breaking of chemical bonds in one direction over all other directions that are possible. This concept can be applied for determining the position of a chemical compound to which a reagent can affect, i.e. protons affected by a strong base.

The term regioselectivity arises from the combination of two chemical concepts that take place in the same chemical reaction; “regio + selective” means the formation of the positional isomer (orconstitutional isomer) is preferred (or selective). All reactions involving regioselectivity give a mixture of constitutional isomers with a major component and a minor component. However, sometimes the minor product is not detectable because it is formed in a very small amount.

What is Stereoselectivity?

Stereoselectivity refers to the formation of an unequal mixture of stereoisomers during a chemical reaction. It simply means that the reaction gives one stereoisomer over another as the final product of the reaction. Also, this type of reactions occurs on two different occasions. One is during the non-stereospecific creation of a new stereocenter, and the other is during the non-stereospecific transformation of an existing stereocenter. This selectivity happens due to空间效应和电子效应。

Stereoselectivity may vary in different reactions but none of the reactions form one total stereoisomer; all these reactions give a mixture of stereoisomers with a major component and a minor component. However, sometimes the minor product is not detectable because it is formed in a very little amount.

有不同类型的立体选择性。

Enantioselective– one enantiomer forms over other isomers; a chiral molecule forms from an achiral molecule, degree of selectivity is measured from enantiomeric excess

非映选择性– one diastereomer forms over the other isomer; one or more chiral centers forms from either an achiral center or a preexisting chiral center, the degree of selectivity can be measured from diastereomeric excess

Stereoconvergence– opposite of the stereoselectivity in which two different stereoisomers form a single stereoisomer

What is the Difference Between Regioselectivity and Stereoselectivity?

术语区域选择性和立体选择性在有机合成中非常重要。区域选择性和立体选择性之间的关键区别在于，区域选择性是指一个位置异构体而不是另一个位置异构体，而立体选择性是指一个立体异构体在另一个位置。因此，区域选择性形成位置或宪法异构体，而立体选择性形成立体异构体。但是，这两种途径构成了另一个异构体作为次要产品，以及首选的异构体，形成为主要产物。此外，对区域选择性的研究属于区域化学，而立体选择性的研究则属于立体化学。

Below infographic summarizes the difference between regioselectivity and stereoselectivity.

概括– Regioselectivity vs Stereoselectivity

术语区域选择性和立体选择性在有机合成中非常重要。The key difference between Regioselectivity and Stereoselectivity is that regioselectivity refers to the formation of one positional isomer over another, whereas stereoselectivity refers to the formation of one stereoisomer over another. The study of regioselectivity comes under regiochemistry, whereas the study of stereoselectivity comes under stereochemistry.

Reference:

1.亨特，伊恩·R。“ ch 6：区域和立体选择性。”UCALGARY，Available here。
2.“立体选择性。”化学库，库，2019年6月5日，Available here。
3. “Stereoselectivity.” Wikipedia, Wikimedia Foundation, 17 Sept. 2019,Available here。

Image Courtesy:

1. “RegioselectivityInhalohydrinformation” By V8rik at English Wikipedia(CC BY-SA 3.0)viaCommons Wikimedia
2.通过解散的“立体选择性halogenative” - 自己的工作(CC BY-SA 3.0)viaCommons Wikimedia