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Difference between Enantiomers and Diastereomers

There are several terms in chemistry that carry different meanings. Chemistry is a branch of science that deals with chemical reactions, chemical compounds, acids, bases, etc. All the gases, acids, etc., have a particular number associated with them. All these numbers are recorded in the periodic table. Now, every action has a reaction. Several acids and bases are mixed to give rise to a third compound that is used for several purposes. For instance, sulfuric acid is formed by mixing sulfuric trioxide with water or sulfur dioxide with oxygen. H2SO4 is industrially made through this contact process. So today, we will be discussing about molecular reactions and compounds, i.e., enantiomers and diastereomers. These two are a part of stereoisomers, i.e., the molecules have the same molecular formula and atoms, but they are distinguished in 3D orientations of atoms. Let us begin by understanding as to what enantiomers and diastereomers mean.

Enantiomers vs Diastereomers


Enantiomer is defined as the chemical compound wherein the mirror images are not superposable. They are a kind of stereoisomers, i.e., the mirror image of one another. Now, how to identify an enantiomer? Well, an enantiomer can be identified by a distinguished direction, i.e., the direction in which they give out the polarized light. The light can either be dextro or levo rotation. Enantiomers are optical isomers. When the two enantiomers are in equal proportions to one another, it is called a racemic mixture. Now, many of us confuse enantiomers with chiral. However, they are different. Enantiomers are molecules existing in two forms that are not superposed on each other, unlike chiral. The base of the structure of the enantiomer is called chiralism. Chiral and enantiomers are different from one another. So, now let us discuss the structure of enantiomers.

  • Enantiomers are originated from chirality.
  • A molecule containing a single atom bonded to four substituents is able to form two enantiomers.
  • It is important for the four substituents to be different. If, in any case, they are the same, then it can lead to a superposed structure of enantiomers that will be achiral.
  • Sometimes a stereocentre might be present in the enantiomers that are commonly seen in chirality.


Diastereomers are defined as the chemical compounds wherein there are non-mirror images. The diastereomers are another form of stereoisomers, having a ring structure. Diastereomers do not have any mirror images. In other words, diastereomers are chemical compounds having the same molecular formula. The elements are non-super-imposable and the images formed are non-mirror. Examples of diastereomers include double bond isomers, cis-trans isomers, and stereoisomers with several chiral centers. Diastereomers are not necessarily optically active, and that is why they differ from enantiomers. Some of the characteristics of diastereomers are that they have a different melting point, a different boiling point, the solubility is varied, and the chemical properties are different. Now, enantiomers and diastereomers are different in several aspects. So, let us look at the significant contrasting points between them.

1. Enantiomers are defined as the chemical compounds wherein the mirror images are not superposed. On the other hand, diastereomers are defined as the chemical compounds in which the elements are non-superimposed, and the non-mirror images are formed.
2. Enantiomers can be distinguished by the polarized light they give out in a particular direction. Diastereomers are identified by the non-mirror images and non-identical stereoisomers.
3. Enantiomers are the mirror images of one another. Diastereomers are non-mirrored images of one another.
4. Every enantiomer has the same chemical and physical properties, except for contacting with chiral compounds. Every diastereomer has a different physical and chemical property.
5. Enantiomers have one or two stereocenters. Diastereomers have two or more stereocenters.
6. Every enantiomer is optically active. Diastereomers are not optically active.
7. Enantiomers have equal but the opposite angle of rotation. Diastereomers do have an equal angle of rotation, unlike enantiomers.
8. The molecular shapes of enantiomers are the same. The molecular shapes of diastereomers are different.
9. The molecules in enantiomers are present in a paired form. The molecules in diastereomers are present separately.
10. Different R, S configuration is present in enantiomers. The R, S configuration is the same in diastereomers. Therefore, this configuration is present in at least one stereocenter.
11. Crystallization or chromatography cannot separate the molecules of enantiomers. The molecules in diastereomers are separated by chromatography and fractional distillation.
12. Examples:
  • Amino Acid
  • Lactic Acid
  • D-alanine
  • L-alanine
  • Chlorine Atom
  • Tartaric Acid
  • Ethyl

So, these are some of the significant contrasting points between enantiomers and diastereomers. They differ majorly in molecular form and configuration. Now, there are several properties associated with enantiomers and diastereomers. So, let us take a look at them.

Characteristics of Enantiomers

  1. Enantiomers have identical physical properties like the boiling point, melting point, NMR spectra, etc.
  2. It is essential to notice the point at which the melting point of one enantiomer is equal to the other; otherwise, the melting points will be different among the two enantiomers.
  3. The melting points between enantiomers can differ due to the intermolecular contact. This is known as stereochemistry. In this, the R and S configurations can differ from one another.
  4. Chiroptical techniques can distinguish the two enantiomers from each other.
  5. The properties of enantiomers are determined by chemical bonds, angles of rotation, torsional angles, etc.

Characteristics of Diastereomers

  1. Diastereomers have varied physical properties like melting point, boiling point, solubility, refractive index, angle of rotation, etc.
  2. Other than geometrical isomers, all diastereomers are optically inactive.
  3. The chemical properties of diastereomers are similar but non-identical.
  4. The reaction rates between two diastereomers differ rapidly.
  5. It is essential to note that the diastereomers can be separated from each other with the help of several techniques like fraction distillation, chromatography, and fractional crystallization.

So, these are some of the properties regarding enantiomers and diastereomers. They both are a form of stereoisomers that have the same molecular interaction but different orientations of atoms. They differ in several aspects like configuration, molecular shapes, compound formation, etc. The major contrasting point between them is that of the images formed, i.e., enantiomers form mirror images, while diastereomers form non-mirror images. Thus, both enantiomers and diastereomers are essential aspects of chemistry that focus on molecular reactions in order to form a compound.

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