Chapter 4, Problem 46PP

Interpretation Introduction

Interpretation:

Energy diagram for different conformations of 2,2-dimethylpropane should be sketched and check the resemblance with the energy diagram for ethane and butane.

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. This rotation 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.

In ethane all the atoms attached to a carbon atom is same, so the energy levels of different eclipsed conformers and staggered conformers are degenerated.

In butane different atoms are attached to a carbon atom, so the energy levels of eclipsed conformers and staggered conformers are not degenerated.

To find: the energy diagram for conformational analysis of 2,2-dimethylpropane is resemble with the energy diagram for ethane or butane conformations.