Chapter 5, Problem 5.55P

Interpretation Introduction

Interpretation:

The isomer expected to have the greater heat of combustion is to be identified, and the reason for it is to be explained.

Concept introduction:

If two molecules are isomers of each other, they have precisely the same combustion products. As a result, any difference in the heat of combustion must be attributed to differences in stabilities of the alkenes. The compound with the smallest heat of combustion is most stable. Double bond stability increases as the amount of alkyl substitution increases due to hyperconjugation. Hyperconjugation involves alpha $\text{C-H}$ $\text{σ}$ bond and $\text{π}$ electrons of double bond. As the number of $\text{C-H}$ $\text{σ}$ bonds next to double bonded carbon atom increases, hyperconjugation increases. Hyperconjugation leads to the stabilization of double bond.