Chapter 4, Problem 4.4P

Interpretation Introduction

Interpretation:

The conformational analysis of $\text{1, 2-dichloroethane}$ (${\text{ClCH}}_{\text{2}}{\text{-CH}}_{\text{2}}\text{Cl}$) by sketching its energy as a function of the ($\text{Cl-C-C-Cl}$) dihedral angle about the $\text{C-C}$ bond is to be performed.

Concept introduction:

In a Newman projection, the bond of interest is not visible. The two atoms are directly connected by the bond of interest. It is imagined to be connected by the front and back carbons. The front carbon atom is shown as a point while the back carbon atom is shown as a circle. The atoms attached to the front carbon converge at the point while the atoms attached to the back carbon are shown connected to the circle.

Anti-conformation: Two wo atoms or groups are ${180}^{\circ }$ apart from each other in a Newman projection. They have the lowest energy of all conformations.

Gauche conformation: Two atoms or groups are ${60}^{\circ }$ apart from each other in a Newman projection.

Eclipsed conformation: Two atoms or groups are ${\text{0}}^{\text{o}}\text{,}{\text{+120}}^{\text{o}}\text{and}{\text{-120}}^{\text{o}}$ apart from each other in a Newman projection. Substituents are identical, and these are not distinguishable.

Staggered conformation: Two atoms or groups are ${\text{-60}}^{\text{o}}\text{and}\text{+}{\text{60}}^{\text{o}}$ apart from each other in a Newman projection.