Axial connection - axial connection

Also called axial bonds or polar bonds. A cyclohexane ring is normally in the shape of a chair, as shown in the diagram below. There are two types of bonds coming out of the carbon atoms in this ring: those that extend parallel to each other above and below the plane of the ring (6 bonds), and those that extend diagonally to the sides (6 bonds). The former are called axial bonds (axial bonds, a) and the latter are called equatorial bonds (e). In monosubstituted cyclohexane, it is more stable when the substituents form equatorial bonds, but the cyclohexane ring can easily be inverted (I II), and an a-bond can become an e-bond, and an e-bond can become an a-bond.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

軸結合，ポーラー結合ともいう．シクロヘキサン環は，普通，下図のようないす形をしている．この環の炭素原子から出ている結合には，環の面の上下に向かって互いに平行に出ている結合(6本)と，斜め横に出ている結合(6本)の2種類があり，前者をアキシアル結合(軸結合，a)，後者をエクアトリアル結合(赤道結合，e)という．一置換シクロヘキサンでは，置換基がエクアトリアル結合をした形のほうが安定であるが，シクロヘキサン環は容易に反転して(Ⅰ Ⅱ)，a結合はe結合に，e結合はa結合になりうる．

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