Chapter 7, Problem 49PP

(a)

Interpretation Introduction

Interpretation:

All the constitutional isomers with the general formula ${\text{C}}_{\text{4}}{\text{H}}_{\text{9}}\text{Br}$ must be drawn and then those must be arranged in order of increasing reactivity towards the S_N2 reaction.

Concept Introduction :

Constitutional or structural isomers are those which differ in bond connectivity. The S_N2 reaction rate decreases with increasing steric crowding.

(b)

Interpretation Introduction

Interpretation:

All the constitutional isomers of ${\text{C}}_{\text{4}}{\text{H}}_{\text{9}}\text{Br}$ must be arranged in order of increasing reactivity towards E2 reaction.

Concept Introduction :

Unlike the S_N2 reaction, reactivity for E2 reaction increases when steric crowding increases.