Chapter 25, Problem 25.77P

Interpretation Introduction

(a)

Interpretation:

The mechanism of the given radical rearrangement reaction is to be drawn.

Concept introduction:

In homolysis, the radicals from a breaking of the weakest bond of the molecule give the major products. The weakest bond possesses the smallest bond dissociation energy. The stability order for radicals is ${\text{methyl radical < 1}}^{\text{o}}{\text{radical < 2}}^{\text{o}}{\text{radical < 3}}^{\text{o}}\text{radical}\text{.}$ Since radicals are electron-poor like carbocation the electron-donating groups increases the stability of radical. In the case of allyl and benzyl radicals the delocalization of the unpaired electron about the entire species. Like carbocation rearrangement radicals also undergo radical rearrangement reaction to form the more stable radical.

Interpretation Introduction

(b)

Interpretation:

What should student conclude regarding the alkyl rearrangement for a given reaction from a ${}^{\text{1}}\text{H NMR}$ spectrum of the product is to be explained.

Concept introduction:

In homolysis, the radicals from a breaking of the weakest bond of the molecule give the major products. The weakest bond possesses the smallest bond dissociation energy. The stability order for radicals is ${\text{methyl radical < 1}}^{\text{o}}{\text{radical < 2}}^{\text{o}}{\text{radical < 3}}^{\text{o}}\text{radical}\text{.}$ Since radicals are electron-poor like carbocation the electron-donating groups increases the stability of radical. In the case of allyl and benzyl radicals the delocalization of the unpaired electron about the entire species. Like carbocation rearrangement radicals also undergo radical rearrangement reaction to form the more stable radical.