Question

What are the differences between enantiomers, diastereomers, and meso compounds?

Answer 1

The stereochemical aspects of compounds have introduced enantiomers, diastereomers, and meso compounds that tell us the stereochemistry and position of various bonds on the molecule in the space orientation. These are all compounds having the same formula but different positions of functional groups or carbons attached at various positions in space.

Complete answer:
The compounds that are tending to rotate in the plane polarized light are termed as optically active. For optically active isomers, a chiral center that is a center having 4 different groups attached is needed. Chiral objects are non – superimposable mirror images. While achiral objects are superimposable mirror images of each other. The stereo chemistry involves enantiomers, diastereomers, and meso compounds, which can be differentiated as:
-Enantiomers: these are the stereoisomers that are non – superimposable mirror images. One of them rotates the polarized light towards right, (S) (d) (+), while the other rotates it towards left, (R) (l) (-). The enantiomers contain different sets of chiral centers in both of their configurations. Example is,

Here, S is changing to R chiral center.
-Diastereomers: they are the stereoisomers that are non – mirror images and are non – superimposable on one another. In these isomers, only one of the chiral centers has a change. Example,

Here, only 2R is changing to 2S chiral center.
-Meso compounds: they are stereoisomers that are optically inactive, and are superimposable mirror images. They consist of two or more than two chiral centers along with a plane of geometry. Example,

Hence, the difference between enantiomers, diastereomers, and meso compounds is justified in their stereochemistry.

Note:
A racemic mixture is that substance that contains an equal amount of mixtures of 2 enantiomers. It is optically inactive as it has 50% d and 50% l configuration that makes its rotation 0. The device used to measure optical activity of any compound is called a polarimeter.