Chapter 14, Problem 14.53P

Interpretation Introduction

Interpretation:

Why the given molecule has quite a large dipole, as indicated in its electrostatic potential map is to be explained.

Concept introduction:

If two unsaturated rings are joined by a conjugated double bond, the electrons of this double bond can move to one of the atoms if it leads to both rings gaining an aromatic character.

These charges, one positive and one negative, are delocalized on the two rings in such a manner as to make both rings aromatic. The charge separation then makes the molecule polar. Due to polarization and delocalization of the electrons over the two rings, the molecule has quite a large dipole moment.