Chapter 16, Problem 16.40P

Interpretation Introduction

Interpretation: The given diene is to be ranked in increasing order of heat of hydrogenation.

Concept introduction: Diene is a hydrocarbon that contains two $\text{C}=\text{C}$ double bonds in a compound.

Conjugated diene consists of two double bonds that are separated by a single bond, whereas isolated diene also consists of two double bond but they are separated by two more carbon atoms.

The example that shows the basic difference between conjugated diene and isolated diene is shown below.

Figure 1

The stability of conjugated diene is more than isolated diene. Due to which the heat of hydrogenation is smaller for conjugated diene, whereas heat of hydrogenation for isolated diene is larger.