Chapter 17.2, Problem 5CC

Interpretation Introduction

Interpretation:

For the given compounds, the most stable compound should be identified.

Concept introduction:

The compounds having two $\text{C}\text{=}\text{C}$ π bonds are called dienes.

Based on the proximity of $\text{C}\text{=}\text{C}$ bonds in dienes, they are classified into three.

• Cumulated dienes: the $\text{C}\text{=}\text{C}$ bonds are located adjacent carbons.
• Conjugated dienes: the $\text{C}\text{=}\text{C}$ bonds or $\text{C}\text{=}\text{C}$ and $\text{C}\text{=}\text{O}$ are separated by one σ-bond.
• Isolated dienes: the $\text{C}\text{=}\text{C}$ bonds are separated by two or more σ-bonds.

The conjugated dienes are more stable as compare to isolated dienes because the delocalization of π bonds is taking place, so this forms some stabilization energy in conjugated system.