Chapter 9, Problem 127P

(a)

Interpretation Introduction

Interpretation:

The product structures of should be drawn in $\text{E2}$ reaction of (1S, 2S)-1-dibromo-1, 2-benylpropane with indication of its configuration.

Concept Introduction:

The ${\text{S}}_{\text{N}}\text{2 }$ reaction is a type of reaction mechanism in which one bond is broken and one bond is formed i.e., in one step. ${\text{S}}_{\text{N}}\text{2 }$ is a kind of nucleophilic substitution reaction mechanism.

An E2 reaction is a concerted, one-step reaction in which the proton and the halide ion are removed in the same step.

For alkyl halide (tertiary, benzylic, and allylic) that can undergo both ${\text{S}}_{\text{N}}\text{2/E2}$ and ${\text{S}}_{\text{N}}\text{1/E1}$ reaction.

A good nucleophile/strong base favors ${\text{S}}_{\text{N}}\text{2/E2}$.

In primary alkyl halides substitution take place.

In secondary alkyl halides substitution and elimination take place (strong. bulky bases and high temperatures favor elimination over substitution).

In tertiary alkyl halides only elimination takes place

(b)

Interpretation Introduction

Interpretation:

The product structures of should be drawn in $\text{E2}$ reaction of (1S, 2R)-1-dibromo-1, 2-benylpropane with indication of its configuration.

Concept Introduction:

The ${\text{S}}_{\text{N}}\text{2 }$ reaction is a type of reaction mechanism in which one bond is broken and one bond is formed i.e., in one step. ${\text{S}}_{\text{N}}\text{2 }$ is a kind of nucleophilic substitution reaction mechanism.

An E2 reaction is a concerted, one-step reaction in which the proton and the halide ion are removed in the same step.

For alkyl halide (tertiary, benzylic, and allylic) that can undergo both ${\text{S}}_{\text{N}}\text{2/E2}$ and ${\text{S}}_{\text{N}}\text{1/E1}$ reaction.

A good nucleophile/strong base favors ${\text{S}}_{\text{N}}\text{2/E2}$.

In primary alkyl halides substitution take place.

In secondary alkyl halides substitution and elimination take place (strong. bulky bases and high temperatures favor elimination over substitution).

In tertiary alkyl halides only elimination takes place.