Chapter 9, Problem 91P

Interpretation Introduction

Interpretation:

The rate constant of deuterated reaction is 7 times lower than hydrogen containing reaction.  The effect of the given statement about the mechanism of the given reaction has to be explained.

Concept introduction:

${\text{S}}_{\text{N}}\text{1/E1}$:

In organic reactions, there is a competition between unimolecular nucleophilic substitution ${\text{S}}_{\text{N}}\text{1}$ and unimolecular elimination $\text{E1}$ reaction.

In ${\text{S}}_{\text{N}}\text{1}$, leaving group is replaced by nucleophile and in $\text{E1}$, the leaving groups are removed to form a alkene.

The strong nucleophile (strong base) facilitates $\text{E1}$ reaction and weak nucleophile facilitates ${\text{S}}_{\text{N}}\text{1}$ reaction.

The formation of stable carbocation is the common intermediate for both reactions.

After formation of carbocation, abstraction of proton yields alkene product in $\text{E1}$ and addition of nucleophile yields a product of ${\text{S}}_{\text{N}}\text{1}$ reaction. Therefore, the reaction or major product is decided by the nucleophile used in the reaction.