Chapter 4, Problem 45PP

Interpretation Introduction

Interpretation:

Relative energy diagram for conformational analysis of 1,2-dichloroethane should be drawn and needed to be label all staggered and eclipsed conformations with the corresponding Newman projection.

Concept introduction:

Conformational analysis is the study of energy verses different conformers. Conformers arise 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.

Newman projection: Newman projection of molecule is one type of representations for the alkanes, where the projection visualization from one carbon to another carbon. In this Newman projection, front carbon which represented as dot is called proximal and the back carbon which represented as circle is called distal.

The most and least energy occupied conformers 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.

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 draw: relative energy diagram for conformational analysis of 1,2-dichloroethane with labeled eclipsed and staggered conformations in Newman projection.