Chapter 4, Problem 4.10YT

Interpretation Introduction

Interpretation:

The rotational energy barrier on going from the anti conformation to one of the gauche conformations is to be indicated in Figure $\text{4-7}$ by an arrow, and the energy barrier is to be estimated.

Concept introduction:

The rotational energy barrier is the energy difference between the beginning conformation and the highest-energy conformation through which the molecule must pass to arrive at the ending conformation.

In Newman projection formula, when the hydrogen on the front carbon covers the hydrogen on the rear carbon, such conformation is called eclipsed conformation, and when the hydrogen atom on the front carbon bisects a pair of $\text{C}-\text{H}$ bonds on the rear carbon, it is called staggered conformation. In eclipsed, the atoms are lined up with each other whereas in staggered, they are equally spaced from each other. The eclipsed conformations pass through maxima, and the staggered conformations occur at minima in the energy diagram.