Which of the following conformers has the highest energy (is the least stable)?

Verified step by step guidance

1. Identify the different conformers presented in the image. Conformers are different spatial arrangements of a molecule that result from rotation around a single bond.
2. Understand that the energy of a conformer is influenced by steric strain, torsional strain, and angle strain. Steric strain occurs when atoms are forced too close to each other, torsional strain arises from eclipsing interactions, and angle strain is due to bond angles deviating from their ideal values.
3. Examine each conformer for steric interactions. Look for large groups that are close to each other, as these will increase steric strain and thus the energy of the conformer.
4. Check for torsional strain by identifying eclipsed conformations. Eclipsed conformations have higher energy compared to staggered conformations due to increased torsional strain.
5. Compare the identified strains in each conformer to determine which has the highest energy. The conformer with the most steric and torsional strain will be the least stable and thus have the highest energy.

Key Concepts

Conformational Analysis

Conformational analysis is the study of the different spatial arrangements of atoms in a molecule that can be interconverted by rotation around single bonds. These arrangements, known as conformers, can have varying degrees of stability based on steric interactions and torsional strain. Understanding conformational analysis is essential for predicting the most stable conformer and identifying which conformer has the highest energy.

Steric Strain

Steric strain occurs when atoms are forced closer together than their natural bond lengths, leading to increased repulsion between electron clouds. In conformers, steric strain can significantly affect stability; conformers with bulky groups in close proximity tend to be less stable due to this strain. Recognizing the impact of steric strain helps in determining which conformer is the least stable.

Torsional Strain

Torsional strain arises from the eclipsing interactions between atoms or groups in a molecule when they are aligned in a way that maximizes repulsion. This strain is particularly relevant in conformers where bonds are rotated into eclipsed positions, leading to higher energy states. Understanding torsional strain is crucial for evaluating the stability of different conformers and identifying the one with the highest energy.