Chapter 9, Problem 94P

Interpretation Introduction

Interpretation:

The given compounds should be ranked in the ordered of most reactive to the least reactive in $\text{E2}$ reaction.

Concept Introduction:

An $\text{E2}$ reaction is a concerted, one-step reaction in which the proton is the more stable alkene, unless the reactants are sterically hindered or the leaving group is poor.

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 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.

Allylic and benzylic halides substitution and elimination takes place (unless they are tertiary).

Tertiary alkyl halides, allylic halides and benzylic halides: substitution and elimination with substitution favored.