Chapter 8, Problem 99P

(a)

Interpretation Introduction

Interpretation:

• The products of the given reaction has to be predicted.

Concept Introduction:

Effect of delocalized electrons on the product of the reaction:

The presence of delocalizes electrons while electrophilic addition or substitution the cation intermediate formed is shifted to stable carbocation form at higher rate, and that leads to the product.

Rule: The stabilities of carbocation are,

${\text{Benzyl cation = allyl cation = 3}}^{\circ }{\text{carbocation > 2}}^{\circ }{\text{ carbocation > 1}}^{\circ }\text{ carbocation > methyl cation > vinyl cation}$

Reactions of conjugated dienes:

An electrophilic addition reaction to a conjugated diene forms both $\text{1,2-addition}$ and $\text{1,4-addition}$ products because the resonance contributors of the allylic cation give cation carbon and the chances for the nucleophile to attack at the electrophilic centre will occur.

(b)

Interpretation Introduction

Interpretation:

• The possible stereoisomers of products generated in the given reaction has to be predicted.

Concept Introduction:

Effect of delocalized electrons on the product of the reaction:

The presence of delocalizes electrons while electrophilic addition or substitution the cation intermediate formed is shifted to stable carbocation form at higher rate, and that leads to the product.

Rule: The stabilities of carbocation are,

${\text{Benzyl cation = allyl cation = 3}}^{\circ }{\text{carbocation > 2}}^{\circ }{\text{ carbocation > 1}}^{\circ }\text{ carbocation > methyl cation > vinyl cation}$

Reactions of conjugated dienes:

An electrophilic addition reaction to a conjugated diene forms both $\text{1,2-addition}$ and $\text{1,4-addition}$ products because the resonance contributors of the allylic cation give cation carbon and the chances for the nucleophile to attack at the electrophilic centre will occur.