Enantiomers - Overview, Structure & Function, Properties, FAQs

Enantiomers: What are they?

Enantiomers is one of the most important concepts to consider when considering stereochemistry.
Molecular stereochemistry:
Three-dimensionality is the meaning of the word stereo. The study of stereochemistry focuses on how the orientation of its atoms in space affects a molecule. Stereoisomerism is a key concept in stereochemistry, which relates to chemical compounds with the same molecular formula but different spatial configurations. Diastereomers and enantiomers are broad categories of stereoisomers.

Also read -

• NCERT Solutions for Class 11 Chemistry
• NCERT Solutions for Class 12 Chemistry
• NCERT Solutions for All Subjects

An optically active system:

Molecules that are capable of rotating plane-polarized light are known as optically active molecules.

The racial structure

Racemic mixtures are equimolar mixtures of dextrorotatory and laevorotatory compounds, i.e., 50% Dextrose and 50% Leo.

Centre Chiral:

The carbon atom attached directly to four distinct groups is called a chiral carbon or chiral centre.

Comparison of enantiomers and chiral compounds

It can be described as the detection of the difference between the two enantiomers of chiral molecules. Enantiomers have the same physical properties that can be used to separate molecular species, so they are hard to distinguish.

The only way to observe physical differences is through interactions with secondary species capable of discriminating.

Enantiomerically oriented molecules are known as chiral molecules.

An enantiomer is a pair of molecules that is a mirror image of one another but cannot overlap or superimpose one onto the other.

Every other aspect of their chemical composition is the same. Enantiomers, or dual isomers, are distinguished by the direction in which they rotate polarized light when they are dissolved in solution; these rotations are labelled as Dextrose (d or +) or Leo (l or -).

Two enantiomers present in equal proportions form a racemic mixture because their optical activities cancel one another. They do not rotate polarized light because both enantiomers are involved simultaneously.

Also Read:

• NCERT solutions for Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes
• NCERT Exemplar Class 12 Chemistry Solutions Chapter 10 Haloalkanes and Haloarenes
• NCERT notes Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes

Enantiomers: Structure and Function

In general, chirality occurs when an atom is tetrahedrally coordinated and bound to four different substituents, as shown in the figure below.

An enantiomer is a mirror image of another that cannot be superimposed.

In the biological world, chirality is the property that allows a molecule to exist as a pair of enantiomers, thus allowing it not to superimpose on its mirror image. The opposite is true for molecules that are achiral when viewed from their mirror image.

There is an enantiomer in every single molecule containing an atom that is tetrahedrally bound to four different substituents.

There is a crucial difference between all four substituents. If any two of them were identical, the structure would become superimposed onto its mirror image, giving rise to the achiral structure. Heterogeneous centres or simply stereo centres are atoms connected to four different atoms.

The stereo enters, which is a widely used although the somewhat misleading alternative term, is a localized property of the molecule that cannot be localized around a single atom or an atomic grouping.

Stereo enters are not required for molecules to show chirality; they're just the most common reason.

Related Topics Link

• Haloalkanes Haloarenes
• Markovnikov Rule
• Wurtz Reaction
• SN1 Reaction Mechanism

Enantiomer properties

The physical properties of enantiomers, such as melting point, boiling point, infrared emission, and NMR spectra, are usually identical. But it is important to realize that even though the melting point, etc., of one enantiomer, is the same as that of the other enantiomer, it is the melting point of the mixture that will differ.

Since the intermolecular interactions between molecules of opposite stereochemistry that are between R and S molecules may be different from those between molecules of like stereochemistry between molecules of either R or S stereochemistry. Optical rotation, the most common chiroptical technique, is the only technique capable of distinguishing the two enantiomers of a compound. One difference between enantiomers is the sign of the torsional angles, which is primarily responsible for a molecule's chiroptical properties.

Purity of optical light:

As an example, let us consider a non-racemic mixture of enantiomers with an optical impurity, and measure how the optical rotation changes for a mixture of compounds with known rotation. This would allow us to determine its optical purity and determine the ratio of the enantiomers. You can calculate the kind of pure enantiomer by dividing the observed specific rotation of a mixture with a pure enantiomers' rotation. If * is the specific rotation, then-Optical Purity = Spectral rotation of the mixture / observed Rotation of pure enantiomers

Also check-

• NCERT Exemplar Class 11th Chemistry Solutions
• NCERT Exemplar Class 12th Chemistry Solutions
• NCERT Exemplar Solutions for All Subjects

NCERT Chemistry Notes:

• NCERT Notes Class 11th Chemistry
• NCERT Notes Class 12th Chemistry
• NCERT Notes For All Subjects