What are Enantiomers?

Dhristi JEE 2022-24

Enantiomers

Enantiomers are a pair of molecules that exist in two forms that can not be superimposed on each other but are mirror images of each other. 


Enantiomers have a Chiral Carbon. A Chiral Carbon is a center of Carbon that is bound to four distinct atoms or groups. The existence of Chiral Carbon is referred to as Chirality (in a molecule). Two molecules in each Chiral Carbon should have different configurations in order to become an Enantiomer. For Example, if a molecule has two Chiral Carbons and another molecule has two Chiral Carbons in the same molecular formula, the two molecules for both Chiral Carbons, not just one Chiral Carbon, should be different.

We discussed Enantiomer’s definition, now let’s study the Chirality and properties of Enantiomers.

  1. It is also important to remember that more than one Chiral characteristic is possible for a molecule. These molecules have many geometric shapes that are considered to have (however, some of these forms may still be perfect mirror images of each other). It should also be noted that the physical and chemical properties of the two Enantiomers are almost identical when the Enantiomers are put in a symmetrical setting. They vary, however, in the directions in which polarised light is rotated by the plane. For instance, if one Enantiomer rotates the polarised light plane to the left, the other Enantiomer rotates the polarised light plane to the right.

  2. Enantiomers are chemically similar in any other respect. A pair of Enantiomers is characterized by the direction in which polarised light is rotated. It can be dextrorotatory or laevorotatory, hence the term optical isomers are used. If two Enantiomers are similarly present, they are collectively referred to as a racemic mixture, a mixture that does not rotate polarized light because the other cancels the optical behavior of each Enantiomer.

Properties of Enantiomers

  1. Enantiomers generally have identical physical properties such as melting point, boiling point, infrared absorptions, and NMR spectra. 

  2. It is important to realize that the melting point of one Enantiomer will be identical to that of the other Enantiomer, the melting point of a mixture of the two Enantiomers may be different. 

  3. This is because the intermolecular interactions between opposite Enantiomers that are between the R and S Enantiomers may be -different from those between Enantiomers that are between two molecules both of R or both of S stereoChemistry.

Structure of Enantiomers

  1. As stereoisomers that are non-superimposable mirror images of one another, Enantiomers were introduced. 

  2. Any molecule which is not superimposed on its mirror image and thus exists is said to be Chiral and to show Chirality as a pair of Enantiomers. In comparison, any molecule which can be superimposed over its mirror image is a aChiral. 

  3. Indeed, it is possible to have two Enantiomers if a molecule contains a single atom that is tetrahedrally bound to four separate substituents.

  4. It is important, however, that the four substituents differ from each other as if two of them were the same, then the structure would become superimposed on its mirror image and thus aChiral. It is better to refer to the atom linked to four distinct atoms as a stereogenic core or simply a stereocenter. 

  5. A commonly used alternate name for a stereocenter, although somewhat misleading, is located around the central atom, whereas Chirality is a property of the molecule as a whole that can not be located around one atom or a group of atoms. 

Chemical Nature of Enantiomers

It is understood that chemical compounds exhibiting stereoisomerism and having different Enantiomeric structures frequently take part in chemical reactions with other Enantiomeric compounds. Currently, Enantiomers are considered to be certain biological molecules. In addition, it is important to remember that two different Enantiomers of the same chemical compound can affect many species in a completely different way. This phenomenon is commonly found in the effects on human beings of various medicines. In certain cases, only one of a drug's Enantiomers would be able to bring about the physiological improvements that are needed.

Did You Know?

Stereoisomers are Classified into diastereomers and Enantiomers. The difference between the two is given below.

Enantiomers 

Diastereoisomers 

They are mirror images of each other.

They are not mirrored images of each other.

Except for the ability to rotate plane-polarized light, they have similar physical properties.

They have distinct physical properties.

They are present in pairs 

They have several molecules.

They have a similar molecular shape

They have different molecular shapes.


Benefits of studying Enantiomers at Vedantu

Enantiomers is a very important topic that gets covered under Chemistry Class 12. In order to get familiar with the chapter, you should start with the basic topics and then reach for covering the complexities involved with the latter part of this chapter.

  • Experts at Vedantu have prepared detailed notes. After referring to the NCERT textbooks, students are advised to go through the explanation of this chapter in clear detail. This will help them to get familiarised with the topic. 

  • In addition to the introduction of Enantiomers, the website of Vedantu provides brief details about Chiral Carbon. It is an essential part of the topic. Chiral Carbon is considered to be the subset of Enantiomers. You can find the standard answers for Chiral Carbon on both the app and the website. 

  • While understanding the concept of Chiral molecules, you should also put your emphasis on learning the similarities and differences between the Chiral Carbon and the Enantiomers themselves. 

  • After learning the introduction of Enantiomers, Vedantu focuses on the properties of these chemical molecules. Questions related to the properties form an important question in your Class 12 board Exams. The properties are explained in detail and simplified language.

  •  Vedantu covers all the Class 12 Chemistry chapters from the NCERT textbook. NCERT books include clear pictures and structural representations related to the Enantiomers. For scoring well in your Exams, it is necessary that you support your answers with the relevant diagrams and structures of Enantiomers. 

  • For the theoretical representation of the structural Enantiomers, Experts at Vedantu have covered the topic in 5 points. These points are kept short and to the point. Students will be able to understand the structure of Enantiomers in an easy manner. 

  • Another important sub-concept that gets covered under the chapter is based on the chemical nature of Enantiomers. It is again, an important question that you should add to your list. In addition to the NCERT textbook, students can refer to the Vedantu website to revise the topic and clear their doubts. 

  • The website also makes sure to contain small yet interactive ways to make the reader at ease. It will help you in grasping the given topics creatively. For Instance- At appropriate intervals, it poses questions to its students in the form of 'Did you know?'. It helps in keeping their minds engaged.

  • In this chapter, students often get a lot of questions related to the differentiation of two terms. While framing your answers, it's important that students use an appropriate tabular representation for the same. Vedantu has clearly described the difference between diastereomers and Enantiomers to help the students in scoring maximum for their Exams. 

FAQs on What are Enantiomers?

1. Are Enantiomers distinct Chemically? 

Aside from their effect on plane-polarized light (they rotate the polarisation axis in equal and opposite amounts) and their interactions with other chiral molecules, enantiomers have the same chemical and physical properties.

2. What is the Significance of a Diastereomer? 

Diastereomers are stereoisomers that do not reproduce the representations of each other and cannot be superimposed over each other. Two or more stereocenters may be stereoisomers of the diastereomers. Determining whether diastereomers are two molecules is often difficult.

3. What are R and S Enantiomers? 

To label the enantiomers of a chiral compound, the "right hand" and "left hand" nomenclature are used. The stereocenters are labeled with R or S. The stereocenter configuration is considered S ('Sinister' Latin= 'left') if the arrow points in a counterclockwise direction (left when leaving the 12 o 'clock position) while R represents a clockwise direction.

4. Elaborate the difference between Enantiomers and anomers?

Enantiomers are known as Chiral molecules. These molecules are exactly similar to each other. These molecules are present in two forms yet despite being similar-looking, they cannot be superimposed on each other. In addition, Enantiomers have a Chiral Carbon that is bound to different atoms and groups. 


Anomers are defined as the stereoisomers of cyclic sugars that differ in their structural arrangement at the hemiacetal or hemiacetal Carbon. In simple terms, anomers are two compounds that consist of more than one Chiral Carbon. Unlike Enantiomers, these two compounds are not the mirror images of each other. 


Another main difference is that Anomers differ at a single Chiral Carbon(as there is more than one Chiral Carbon) while Enantiomers are different at all Chiral Carbons in the molecule. 

5. How to make diagrams for Enantiomers?

The concept of Enantiomers is categorised under organic Chemistry. It is important for the students to practice their diagrams from Enantiomers. One of the most asked diagrams is related to the structure of Enantiomers. The easiest way of drawing is by making the compound structure and then adding relevant wedges and dashes to it. It's also essential that you draw a mirror reflection of the same. Labelling is another step to make your diagram presentable and correct.


Quick tip- While practicing the mirror image of the Enantiomers, you can simply place a mirror in front of the diagram to avoid mistakes. It will help you to master it and save your time during your final Exams.

6. What are some of the Examples for Enantiomers?

For following the correct order in your answer, students should begin by adding a standard definition of Enantiomers. Experts at Vedantu have framed a simplified yet complete definition of Enantiomers. You can visit the website to have full access. 


An important Example of Enantiomers is of two forms of tartaric acid that are optically active. These are symbolised as d-tartaric acid and l-tartaric acid. These two acids are similar in terms of their melting point and densities. They are also identical in terms of reaction rates and solubility.

7. How are Enantiomers different from Chiral Carbon?

Explaining the difference between Chiral Carbon and Enantiomers, Chiral Carbon is considered to be the subset of Enantiomers. The main difference in these two terms is reflected through what they describe. Chiral Carbon tells about the atom while Enantiomer compares the two different molecules and how they are related. However the term Chiral is still used in all the definitions of Enantiomers. Hence, the students shouldn't get confused between these two. For understanding this chapter in detail, you can refer to the website of Vedantu and have all your doubts cleared by their experts. 

8. Does Enantiomers Class 12 involve multiple-choice questions?

Taking note of the latest changes made by the CBSE in their renewed curriculum, the board has decided to focus on the conceptual learning of the students. Enantiomers Class 12 can include several Mcq questions for their Exams. For instance- Students can be asked to identify the right property of Enantiomer from the given options. In order to answer such questions,you should read and understand the concept with full attention. At the website of vedantu, you can take a quick revision of important points and get ready to answer the objective questions by avoiding confusion. 

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