Difference Between Enantiomers and Diastereomers

Enantiomers are the chiral molecules that are mirror images of one another and are not superimposable. Diastereomers are the stereomer compounds with molecules that are not mirrored images of one another and that are not superimposable. They are non-superimposable mirror images of each other. This means that they are mirror images of each other, but you can't stack them on top of each other and have them line up exactly the same. Enantiomers and diastereomers are types of stereoisomers. In this lesson, we'll learn what the difference is between these types of stereoisomers and how to differentiate between them.

There are two types of Isomers, stereoisomers, and structural isomers. Structural isomers have the same molecular formula but are different in their bond connection and order. On the other hand, Stereoisomers, differ in the spatial arrangement of their structures.

Again the stereoisomers are divided into Enantiomers and Diastereomers. Enantiomers and diastereomers are that the former is found as mirror images while the latter isn’t that is the main difference.

What are Enantiomers and Diastereomers?

Enantiomers:

Enantiomers are the chiral molecules that are mirror images of one another and are not superimposable. A chiral molecule has an image that is not the same as its mirror image and, it is typically characterized by a carbon centre with 4 different atoms bonded to it. These atoms must be chemically distinguishable for a molecule to be qualified as a chiral and thus an Enantiomer. The tetrahedral carbon to which the different atoms are attached to is called the stereocenter. See the difference below, the two molecules have the same formula and the structuring of the atoms so to identify them we have to label one the S and the other R, depending on the clockwise configuration of the atoms from the lowest atomic mass to highest atomic mass.

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Diastereomers:

Diastereomers are the stereomer compounds with molecules that are not mirror images of one another and that are not superimposable. The perfect example of diastereomers is when you look at the cis and trans isomer structure. See the cis-2-butene and the trans-2-butene structures below:

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See the compounds are identical but the arrangements are different, and they are not the mirror images of each other. When the CH3 are on the same side, the compound is cis and when the other is swapped with the Hydrogen atom, we name the compound trans. There are plenty of these molecules, as long as they demonstrate the spatial arrangements of atoms that are not mirrored images of each other, and that are not superimposable.

Enantiomers vs Diastereomers 

              Enantiomers

              Diastereomers

Enantiomers are non-superimposable mirror images of each other

Enantiomers are mirror images of each other which are known as stereoisomers.

Diastereomers are also non-superimposable but are not mirror images of each other.

Diastereomers are not mirrored images of each other which are known as stereoisomers.

All enantiomers have the same physical and chemical properties except, interaction with eight and interaction with other chiral compounds.

All diastereomers have different physical and chemical properties.

Enantiomers have one or more stereocenters.

Diastereomers have two or more than two stereocenters.

All Enantiomers pass optical activity. They have equal but opposite angles of rotation.

Not all Diastereomers pass the optical activity. They do not have an equal angle of rotation.

In the Enantiomers the Shapes of molecules are similar.

Diastereomers have different molecular shapes.

Enantiomers are present in pairs.

There can be several molecules in Diastereomers.

They always have a different R, S-configuration.

They have the same R, S-configuration at least at one stereocenter.

They can not be separated by crystallization, chromatography, etc.

They can be separated by fractional distillation, chromatography, etc.

Example: Lactic acid

Example: Tartaric acid


Conclusion

Enantiomers differ at the configuration of every stereocenter. Molecules that are not mirror images due to the spatial arrangements of atoms are diastereomers. The main difference between enantiomers and diastereomers is that the former is a mirror image but the later is not a mirror image.

Examples

Saccharide (or sugar) is a biological example in chemistry and below is the Enantiomers and Diastereomers of throes. 5DHT is an example of these-

Fun Facts

Enantiomers are the molecules that are mirror images but non-superimposable. If they are not superimposable, and they are not mirrored images of one another then they're diastereomers. Because their atoms are different from the fact that stereoisomers are isomers. If two stereoisomers are mirror images of each other then it is called enantiomers. Diastereomers are not enantiomers, these are stereoisomers. If every stereocenter is the opposite orientation, then it's an enantiomer, if not then it's a diastereomer. The mirror image stereoisomers are one of the interesting types of isomers, and a set of two molecules which are non-superimposable.

FAQ (Frequently Asked Questions)

1. How can you Distinguish Between Enantiomers and Diastereomers?

An enantiomer is a stereoisomer that's a non-superimposable mirror image of each other, and a diastereomer is a stereoisomer with two or more stereocenters, and the isomers are not mirrored images of each other. Enantiomers have every single stereocenter in opposite orientations, such as with D-glucose and L-glucose, while diastereomers have at least one stereocenter in the opposite orientation, but every stereocenter is not in the opposite orientation, such as with D-glucose and D-galactose.

2. How do you Identify Enantiomers or Diastereomers?

First of all, Identify all of the stereocenters in the molecule. Then determine the orientation of each stereocenter on both molecules (R or S). In the end, compare the orientations of each stereocenter. If every stereocenter is the opposite orientation, then it's an enantiomer, if not then it's a diastereomer.

3. What are Diastereomers for Example?

The compounds which have the same bond configuration at one stereocenter but different configurations at another stereocenter are known as Diastereomers.

For example consider two compounds with a six-membered ring that have two substituents each, a chlorine atom and an ethyl group, these compounds are Diastereomers.