Chapter 19, Problem 19.75P

Interpretation Introduction

(a)

Interpretation:

Synthesis of the given target molecule from phenylmethanol (benzyl alcohol) is to be determined.

Concept introduction:

${\text{KMnO}}_{\text{4}}$ acts as an oxidizing agent. For the conversion of alcohol group to acid group, ${\text{KMnO}}_{\text{4}}$ is used.

Acid is converted to ester group by esterification reaction with the help of a strong base like ${\text{NaH and CH}}_{\text{3}}\text{Br}$.

Answer to Problem 19.75P

Synthesis of the target molecule from phenylmethanol (benzyl alcohol) is

Explanation of Solution

Structure of the target molecule is

In the first step of the reaction, phenylmethanol (benzyl alcohol) is treated with oxidizing agent ${\text{KMnO}}_{\text{4}}$ which converts the alcohol group to carboxylic acid. The product for this step is benzoic acid.

In the second step of the reaction, benzoic acid undergoes esterification reaction. In this step, benzoic acid is first treated with a strong base like $\text{NaH}$ which abstracts the acidic proton. Then, we add methyl bromide $\left({\text{CH}}_{\text{3}}\text{Br}\right)$ which undergoes nucleophilic substitution reaction resulting in the formation of the methyl benzoate group.

The complete synthesis of the target molecule is as shown below.

Conclusion

By using the functional group conversion reactions, synthesis of the target molecule is determined.

Interpretation Introduction

(b)

Interpretation:

Synthesis of the given target molecule from phenylmethanol (benzyl alcohol) is to be determined.

Concept introduction:

For the conversion of alcohol group to Grignard reagent, alcohol (bad leaving group) is treated with ${\text{PBr}}_{\text{3}}$ and $\text{Mg}$ in presence of ether group.

When Grignard reagent is reacted with ketone, in presence of acidic condition ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$, it results in the formation of tertiary alcohol.

For the removal of water, tertiary alcohol is treated with conc. ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ in presence of heat which results in the formation of alkene.

The bromination reaction on alkene takes place in presence of ${\text{Br}}_{\text{2}}{\text{ in CCl}}_{\text{4}}$. This gives vicinal dihalide.

Answer to Problem 19.75P

Synthesis of the target molecule from phenylmethanol (benzyl alcohol) is

Explanation of Solution

Structure of the target molecule is

In the first step, the formation of Grignard reagent takes place. In this step, benzyl alcohol is treated with ${\text{PBr}}_{\text{3}}$ and $\text{Mg}$ metal in presence of ether. In the second step, this Grignard reagent is treated with acetone and ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ which results in the formation of tertiary alcohol. In the third step, the removal of water takes place in presence of acid like ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ in presence of heat thus resulting in the formation of alkene $\left(\text{C=C}\right)$. In the last step, bromination reaction on alkene takes place in presence of ${\text{Br}}_{\text{2}}{\text{ in CCl}}_{\text{4}}$. This gives vicinal dibromide.

The complete synthesis of the target molecule is as shown below.

Conclusion

By using the functional group conversion reactions, the synthesis of the target molecule is determined.

Interpretation Introduction

(c)

Interpretation:

Synthesis of the given target molecule from phenylmethanol (benzyl alcohol) is to be determined.

Concept introduction:

$\text{PCC}$ is used for the oxidation of alcohol into aldehyde.

Grignard reagent, in presence of acidic condition, is used for the conversion of aldehyde or ketone to alcohol.

For the removal of water, tertiary alcohol is treated with conc. ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ in presence of heat which results in the formation of alkene.

Reaction of alkene with diazomethane in presence of heat results in the formation of cyclopropane ring.

Answer to Problem 19.75P

Synthesis of the target molecule from phenylmethanol (benzyl alcohol) is

Explanation of Solution

Structure of the target molecule is

In the first step, benzyl alcohol is treated with the oxidizing agent $\text{PCC}$ which results in the oxidation of alcohol to aldehyde. The product of this step is benzaldehyde.

In the second step, benzaldehyde is treated with Grignard reagent $\left({\text{CH}}_{\text{3}}\text{MgBr}\right)$ and ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ that results in the conversion of carbonyl group of benzaldehyde to secondary alcohol.

In the third step, the presence of conc. ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ and heat, removes water which gives alkene.

In the last step, alkene is treated with diazomethane in presence of heat that results in the formation of the cyclopropane ring.

The complete synthesis of the target molecule is as shown below.

Conclusion

By using the functional group conversion reactions, the synthesis of the target molecule is determined.

Interpretation Introduction

(d)

Interpretation:

Synthesis of the given target molecule from phenylmethanol (benzyl alcohol) is to be determined.

Concept introduction:

$\text{PCC}$ is used for the oxidation of alcohol into aldehyde.

Grignard reagent, in presence of acidic condition, is used for the conversion of aldehyde or ketone to alcohol.

Answer to Problem 19.75P

Synthesis of the target molecule from phenylmethanol (benzyl alcohol) is

Explanation of Solution

Structure of the target molecule is

In the first step, benzyl alcohol is treated with the oxidizing agent $\text{PCC}$ which results in the oxidation of alcohol into aldehyde. The product of this step is benzaldehyde.

In the second step, benzaldehyde is treated with Grignard reagent $\left({\text{PhCH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{MgBr}\right)$ and ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ that results in the conversion of carbonyl group of benzaldehyde to secondary alcohol.

The complete synthesis of the target molecule is as shown below.

Conclusion

By using the functional group, conversion reactions synthesis of the target molecule is determined.