Chapter 11, Problem 11.16P

Interpretation Introduction

(a)

Interpretation:

The reason as to why methyl iodide and $\text{1-butanol}$ are formed when methyl ether $\left(\text{1-methoxybutane}\right)$ is treated with $\text{HI}$ and only a little amount of methanol and $\text{1-iodobutane}$ formed is to be stated.

Concept introduction:

Ether cleavage reactions are those reactions in which an ether reacts with $\text{HI}$ and $\text{HBr}$ to yield less hindered alkyl halide and alcohol. Protonation of oxygen of ether makes alcohol a good leaving group. Primary ether reacts by ${\text{S}}_{\text{N}}2$ mechanism.

Interpretation Introduction

(b)

Interpretation:

The reason as to why $\text{1-iodobutane}$ is formed when reaction mixture in part (a) is heated for a longer time is to be stated.

Concept introduction:

Ether cleavage reactions are those reactions in which an ether reacts with $\text{HI}$ and $\text{HBr}$ to yield less hindered alkyl halide and alcohol. Protonation of oxygen of ether makes alcohol a good leaving group. Primary ether reacts by ${\text{S}}_{\text{N}}2$ mechanism.

Interpretation Introduction

(c)

Interpretation:

The reason as to why $tert\text{-butyl}\text{iodide}$ and methanol are formed when $tert\text{-}\text{butyl}\text{methyl}\text{ether}$ is treated with $\text{HI}$.

Concept introduction:

Ether cleavage reactions are those reactions in which an ether reacts with $\text{HI}$ and $\text{HBr}$ to yield less hindered alkyl halide and alcohol. Protonation of oxygen of ether makes alcohol a good leaving group. When tertiary ether reacts with alkyl halide the reaction occurs by ${\text{S}}_{\text{N}}1$ mechanism.

Interpretation Introduction

(d)

Interpretation:

The reason as to why $tert\text{-butyl}\text{methyl}\text{ether}$ cleaves faster than $tert\text{-butyl}\text{methyl}\text{sulfide}$ in $\text{HBr}$.

Concept introduction:

Ether cleavage reactions are those reactions in which an ether reacts with $\text{HI}$ and $\text{HBr}$ to yield less hindered alkyl halide and alcohol. Protonation of oxygen of ether makes alcohol a good leaving group. When tertiary ether reacts with alkyl halide the reaction occurs by ${\text{S}}_{\text{N}}1$ mechanism

Interpretation Introduction

(e)

Interpretation:

The reason as to why enantiomerically pure $\left(S\right)\text{-2-butanol}$ and methyl bromide are formed when enantiomerically pure $\left(S\right)\text{-2-methoxybutane}$ is treated with $\text{HBr}$.

Concept introduction:

Ether cleavage reactions are those reactions in which an ether reacts with $\text{HI}$ and $\text{HBr}$ to yield less hindered alkyl halide and alcohol. Protonation of oxygen of ether makes alcohol a good leaving group. Primary ether reacts by ${\text{S}}_{\text{N}}2$ mechanism.