Chapter 7, Problem 69IP

Interpretation Introduction

Interpretation: The mechanism for the given reaction should be identified.

Concept Introduction:

${\text{S}}_{\text{N}}2$Reaction: It is a nucleophilic substitution reaction in which the rate determining step depends on both of the molecules involved. The bond making and the bond breaking process happens simultaneously in this reaction.

Structure of the substrate plays major role in the reactivity of ${\text{S}}_{\text{N}}2$ reaction. If the substrate is more substituted then the rate of the reaction will becomes slower. Since the mechanism of ${\text{S}}_{\text{N}}2$ reaction proceeds through backside attack on the substrate, it depends on steric factor that if more groups attached near the leaving group the reactivity becomes slower. The ${\text{S}}_{\text{N}}2$ reactivity increases in molecule with better leaving group. The reactivity increases in the order as follows,

Carbocation: it is carbon ion that bears a positive charge on it.

Leaving group: it is a fragment that leaves substrate with a pair of electrons via heterolytic bond cleavage.

Nucleophile: donates pair of electrons to positively charged substrate resulting in the formation of chemical bond.