Chapter 4, Problem 56PP

Interpretation Introduction

Interpretation:

The given conformations are needed to be ranked in order of increasing energy.

Concept introduction:

Conformations are arising due to the free rotation of $\text{C}-\text{C}$ bond. These rotations are measured by dihedral angle; it is the angle between two atoms attached to two different carbons of $\text{C}-\text{C}$ rotation in Newman projection.

The most and least energy occupied conformations are eclipsed and staggered, which are having a dihedral of ‘0’ and ‘60’ degree respectively.

Staggered conformation: conformation is said to be staggered when groups (attached to front and back carbons) are not aligned in the same axis.

Eclipsed conformation: conformation is said to be eclipsed when groups (attached to front and back carbons) are aligned in the same axis.

Because of the high torsional strain between atoms of eclipsed conformations, makes them more energized as compared to staggered conformations.

For eclipsed conformations, Torsional strain and steric interactions of atoms are the energizing factors.

For staggered conformations, anti-interactions and gauche interactions of atoms are the energizing factors.

To rank: the given conformations in order of increasing energy.