Intro to Organic - Plane of Symmetry (Optical Isomers)

In an earlier entry of stereoisomerism, I discussed about (i) Geometric Isomerism and (ii) Optical Isomerism. In this entry, I will be discussing about the significance of having the plane of symmetry which affects whether a sp³ carbon is chiral (or not).

The diagram below shows that when a sp³ carbon has two (at least) substituents to be identical, there will be a plane of symmetry which is able to cut the molecule into identical halves.The impact of this plane of symmetry is that when we rotate the mirror image of the structure, we will be able to obtain the original structure. This implies that the mirror image can superimpose the structure, which means that the mirror image is NOT unique. To substantiate my argument. Another picture is used to illustrate the angle of rotation such that the mirror image and structure superimpose with each other.This concludes that optical isomerism does not exist when a plane of symmetry is present. - Being able to see the plane of symmetry is another useful technique and it is helpful when you trying to determine the existence of chiral centre on small molecules.

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^{Article written by Kwok YL 2009.}

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