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Conformational Analysis - Factors affecting the stability of conformers

Learning Objective: To study the various stabilizing and destabilizing interactions affecting the stability of conformations. 

Skill Level - Intermediate

 

Prerequisites: 

 

Chapter: Stereochemistry

Sub-topic: Conformational Isomerism

 

Author's Note: Conformations are possible for molecules only when they find a stable orientation in space, supported by stabilizing interatomic interactions. This section covers when conformations adopted by rotating molecules are stable and when they are unstable.  

Conformational Analysis - Factors affecting the stability of conformers

Different conformations obtained due to the rotation of the single bonds in a molecule vary in energy, and the energy level affects its stability. So, conformational analysis studies and establishes a relationship between various conformers and their energy levels.  

It has been found that a stable conformation has lower energy, so the relationship between potential energy and stability is of the inverse type - the higher a system's potential energy, the lower its stability. 

One conformer may have an arrangement due to bond rotation that is more stable and lower in energy than the previous conformer. Therefore, absolute energy or stability is a myth; these are always relative concepts.

Stability is always measured relative to a previously agreed-upon standard or the best possible arrangement. For example, staggered conformation is relatively preferred over eclipsed conformation in some destabilizing situations. 

So, the bond doesn't have to keep turning in the wrong direction and keep making mistakes that increase its energy. There is always a turnaround in the right direction. And for that, understanding which factors affect the stability of conformations is very important.

 

Factors affecting the stability of conformers

Destabilizing Interactions

Three main factors increase the potential energy of conformers and, therefore, decrease their stability. These destabilizing factors are: Steric Interactions, Torsional Strain, and Angle Strain.

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Stabilizing Interactions

Three factors stabilizing conformations are: Hyperconjugation, Intramolecular Hydrogen Bonding, and Dipole-Dipole Interactions

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Subscribe to learn about all stabilizing and destabilizing interactions affecting the conformers. 

Stereochemistry
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Stereoisomerism - Conformation and Configurational Isomerism

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