Chapter 21, Problem 21.84P

Interpretation Introduction

(a)

Interpretation:

Mechanism of the given reaction is to be determined.

Concept introduction:

In nucleophilic addition reaction nucleophile is attack on most electrophilic carbon atom results in the formation of new bond between nucleophile and electrophilic carbon atom.

In case of nucleophile elimination, good leaving group $\left({\text{N}}_{\text{2}}\right)$ is expelled to reform the carbonyl bond.

Interpretation Introduction

(b)

Interpretation:

The reason for the conversion of more stable six membered ring to a less stable seven membered ring is to be explained.

Concept introduction:

The expansion of the ring is carried out in nucleophile elimination step.

Alkyl group is shifted to such a carbon which is attached to the good leaving group like ${\text{N}}_{\text{2}}$.