Chapter 21, Problem 21.50AP

Interpretation Introduction

(a)

Interpretation:

The reaction of capsaicin, with ${\text{Br}}_{\text{2}}/{\text{CHCl}}_{\text{2}}$ is to be predicted.

Concept introduction:

One of the common reactions of alkene is electrophilic addition reaction. An electrophile attacks the double bond and gives the addition product. When unsaturated alkenes are treated with bromine in presence of dichloroethane, they undergo addition reaction and dibromo products are obtained.

Interpretation Introduction

(b)

Interpretation:

The reaction of capsaicin with dilute aqueous $\text{NaOH}$ is to be predicted.

Concept introduction:

In presence of base amides get hydrolyzed. The amide bond $-\text{NH}-\text{C}=\text{O}$ dissociates upon reaction with dilute aqueous $\text{NaOH}$ to give an amine and the corresponding sodium salt of carboxylic acid. This hydrolysis is used to get amines from corresponding amides.

Interpretation Introduction

(c)

Interpretation:

The reaction of capsaicin with dilute aqueous $\text{HCl}$ is to be predicted.

Concept introduction:

Amides can easily be hydrolyzed in presence of dilute acid or bases. Amides upon reaction with dilute aqueous hydrochloric acid get hydrolyzed to form a carboxylic acid and corresponding ammonium salt. Amines can be extracted by hydrolysis of corresponding amides.

Interpretation Introduction

(d)

Interpretation:

The reaction of capsaicin with ${\text{H}}_2$ in presence of a catalyst is to be predicted.

Concept introduction:

In presence of a catalyst the unsaturated bond can be saturated by addition of hydrogen gas. The hydrogen is added to both carbons of double bond. Capsaicin undergoes hydrogenation reaction with hydrogen in presence of a catalyst.

Interpretation Introduction

(e)

Interpretation:

The reaction that occurs when product of part (d) is heated with $\text{6}M$ $\text{HCl}$ is to be predicted.

Concept introduction:

The amide bond can be hydrolyzed in the presence of base or acid. When the amide bond is hydrolyzed in the presence of base as catalyst, then an amine and carboxylate salt is formed. However, when the amide bond is hydrolyzed in the presence of acid, an ammonium salt and carboxylic acid is formed.

Interpretation Introduction

(f)

Interpretation:

The reaction of product of part (b) with ${\text{CH}}_3^{}\text{I}$ is to be predicted.

Concept introduction:

The sodium salts of carboxylic acids are used to get compound with higher number of carbon atoms. The sodium salts of carboxylic acids are treated with alkyl halide to convert carboxylate group into an ester. The ester fromed in the reaction has desired number of carbon atoms.

Interpretation Introduction

(g)

Interpretation:

The reaction of product of part (d) when heated with concentrated aqueous $\text{HBr}$ is to be stated

Concept introduction:

The amide bond can be hydrolyzed in the presence of base or acid. When the amide bond is hydrolyzed in the presence of base as catalyst, then an amine and carboxylate salt is formed. However, when the amide bond is hydrolyzed in the presence of acid, an ammonium salt and carboxylic acid is formed.