Stereoisomerism

Stereoisomers are compounds that have the same chemical and structural formulae but differ in the relative arrangement of the atoms or groups in space, a phenomenon known as stereoisomerism.

Stereoisomerism can be divided into two categories:

Conformational Isomers

Conformational isomers are stereoisomers having different relative positions of atoms inside the molecule that can be interconverted by rotating around sigma links. In other words, there is no need to break and re-make covalent bonds in order to interconvert these isomers.

Configurational Isomers

Stereoisomers that can only be interconverted by breaking and reconstructing covalent bonds rather than rotating around sigma bonds are known as configurational isomers. Geometrical isomerism and optical isomerism are the two types of configurational isomerism.

Geometrical Isomerism 

Isomerism generated by constrained rotation around a link in a molecule is known as geometrical and also called cis-trans isomerism. A wide range of substances exhibits geometrical isomerism, which can be characterized as follows:

• C=C, C=N, and N=N are examples of compounds with double bonds.
• A cyclic molecule, including homocyclic, heterocyclic, and fused ring systems.
• Steric hindrance compounds prevent rotation around a single bond. Biphenyls, for example.

Optical Isomerism 

Certain chemicals can exist in two stereoisomeric forms that are incompatible with one another. These isomers have equal physical properties, such as melting point, boiling point, refractive index, density, solubility, and so on, despite the change in atom arrangement.

They are also similar in most of their chemical interactions. They only differ in their behaviour when it comes to plane polarised light; one rotates it to the right, while the other rotates it to the left, but to the same degree. An optical isomer is a pair of chemicals that have the same optical properties.

Optical isomers are two compounds that contain the same number and type of atoms, bonds, and spatial configurations of the atoms but are not superimposable mirror images of each other. Enantiomers are isomers that are non-superimposable mirror reflections of each other.

Isomerism refers to the phenomenon where two or more compounds have the same molecular formula but different structural arrangements or spatial orientations, resulting in distinct chemical properties. These compounds with the same formula but different structures are called isomers.

Let’s learn about isomerism in detail, including its types and examples.