Chapter 7, Problem 54PP

(a)

Interpretation Introduction

Interpretation:

The configuration of the chiral center has to be identified for given substrate.

Concept Introduction:

Chirality: It refers to a Carbon atom in a molecule that contains four different substituents.

Enantiomers: they are chiral molecules whose mirror images are not superimposable.

R and S nomenclature: it is used to assign the molecule with chiral carbon using CIP rules.

The CIP rules are as follows:

1. 1. Select the chiral carbon and assign the numbers to the atoms in the decreasing order of their atomic mass by placing the hydrogen atom below the plane.
2. 2. If the numbering follows clockwise direction then the molecule is termed as R and if it follows anti-clockwise direction then molecule is termed as S.
3. 3. Suppose if the hydrogen is placed above the plane then the corresponding isomer is just opposite to the resulting isomer.

(b)

Interpretation Introduction

Interpretation:

The reaction mechanism and the configurations of substrate and product for the given reaction should be assigned.

Concept Introduction:

Chirality: It refers to a Carbon atom in a molecule that contains four different substituents.

Enantiomers: they are chiral molecules whose mirror images are not superimposable.

R and S nomenclature: it is used to assign the molecule with chiral carbon using CIP rules.

The CIP rules are as follows:

1. 1. Select the chiral carbon and assign the numbers to the atoms in the decreasing order of their atomic mass by placing the hydrogen atom below the plane.
2. 2. If the numbering follows clockwise direction then the molecule is termed as R and if it follows anti-clockwise direction then molecule is termed as S.
3. 3. Suppose if the hydrogen is placed above the plane then the corresponding isomer is just opposite to the resulting isomer.

(c)

Interpretation Introduction

Interpretation:

The reaction mechanism and the configurations of substrate and product for the given reaction should be assigned.

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 making process happens simultaneously in this reaction, which results in the inversion of configuration.

$\text{Rate}\text{= k}\left[\text{alkylhalide}\right]\text{×}\left[\text{nucleophile}\right]$

Structure of the substrate plays major role in ${\text{S}}_{\text{N}}2$ reaction. If the substrate is more substituted the rate of the reaction 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 more groups attached near the leaving group the reactivity becomes slower.