Chapter 25, Problem 25.9P

Interpretation Introduction

Interpretation:

For each of the molecules shown here, the weakest C-H bond is to be indicated.

The weaker of those two C-H bonds is to be determined and the reason for it is to be explained.

Concept introduction:

Although free radicals tend to be very unstable, we can assign different relative stabilities to various radicals, based on the energy required to produce them via homolysis. Alkyl radical stability increases in the order: ${\text{methyl < 1° < 2 }}^{\text{ο}}{\text{< 3}}^{\text{ο}}$. Alkyl radical stability decreases as the effective electronegativity of the carbon atom that gains the unpaired electron increases. The radicals having more resonance structures are more stable. We can compare the strength of C-H single bond on the basis of stability of radicals formed by homolysis. More stable the radicals, weakest the bond.