Chapter 7, Problem 104CP

Interpretation Introduction

Interpretation:

X-ray crystallographic analysis of compound 3 shows retention of configuration, which is unexpected.  With the help of possible mechanism, the unexpected result has to be explained.

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.  A general ${\text{S}}_{\text{N}}2$ reaction mechanism is given as,

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.