Chapter 4.8, Problem 21ATS

Interpretation Introduction

Interpretation:

In the Ethylene glycol, the gauche conformation is having lower in energy than the anti-conformation should be explained.

Concept Introduction:

Newman projection:

• The conformational isomers are representing by the Newman projection drawing.
• Newman projection representing by front carbon atom connected to 3 groups then the 3 groups connected circle is a back carbon atom.
• In the Newman projection, the atoms or groups are attached to the center carbon by angle of $\text{60°}$ and this is called as a dihedral angle.
• The dihedral angle is varying by the rotation of C-C bond, result of this there are two conformations are obtained and this are staggered and eclipsed conformations obtained.
• The highest energy conformation is eclipsed and lowest energy conformation is staggered.
• Interaction between the groups present in the front and back carbon atoms are increases the energy of a compound all so increases.

Intramolecular hydrogen bonding:

• The bond between the electronegative atom and bonded hydrogen present in the same compound is called is called intramolecular hydrogen bonding.

To explain the Gauche is lower energy than anti in Ethylene glycol.