Chapter 4, Problem 4.6YT

Interpretation Introduction

Interpretation:

The torsional strain in a molecule of ethane in an eclipsed conformation is to be estimated using Figure $4.4$.

Concept introduction:

In Newman projection formula of an ethane, when the hydrogen on front carbon covers the hydrogen on rear carbon, such conformation is called eclipsed conformation, and when the hydrogen atom on front carbon bisects a pair of $\text{C}-\text{H}$ bonds on the rear carbon, it is called staggered conformation. In eclipsed conformation, the angle between two hydrogen atoms on adjacent carbon atoms, $\text{H}-\text{C}-\text{C}-\text{H}$, is called dihedral angle. The increase in energy due to electrostatic repulsion in the $\text{C}-\text{H}$ bonds in eclipsed conformation is called torsional strain. Thus, this is the energy difference between eclipsed and staggered conformation.