Chapter 19, Problem 22P

(a)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Aromatic five-membered heterocyclic compounds undergo electrophilic aromatic substitution reactions preferentially at 2-position. The intermediate obtained by adding a substituent to this position is more stable than the intermediate obtained by adding a substituent to C-3 position.

(b)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Pyridine is more reactive than benzene towards nucleophilic aromatic substitution reactions. Nucleophile adds to the ring carbon attached to the leaving group. Then, the leaving group is eliminated. Substitution takes place at C-2 or C-4 because it leads to the most stable intermediate.

(c)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Alkyl halides undergo nucleophilic substitution reaction with cyanide ions to give nitriles. Nitriles are reduced to amines in the presence of ${\text{H}}_{\text{2}}$ and raney $\text{Ni}$.

(d)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Aromatic five-membered heterocyclic compounds undergo electrophilic aromatic substitution reactions preferentially at 2-position. The intermediate obtained by adding a substituent to this position is more stable than the intermediate obtained by adding a substituent to C-3 position.

(e)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Pyridine is more reactive than benzene towards nucleophilic aromatic substitution reactions. Nucleophile adds to the ring carbon attached to the leaving group. Then, the leaving group is eliminated. Substitution takes place at C-2 or C-4 because it leads to the most stable intermediate.

(f)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Alkyl halide reacts with amine to form alkyl-substituted product. The reaction mechanism is nucleophilic aliphatic substitution. Amines are generally nucleophilic in nature. Therefore, the reaction easily occurs in mild conditions.

(g)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Aromatic five-membered heterocyclic compounds undergo electrophilic aromatic substitution reactions preferentially at 2-position. The intermediate obtained by adding a substituent to this position is more stable than the intermediate obtained by adding a substituent to C-3 position.

(h)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Pyridine is more reactive than benzene towards nucleophilic aromatic substitution reactions. Nucleophile adds to the ring carbon attached to the leaving group. Then, the leaving group is eliminated. Substitution takes place at C-2 or C-4 because it leads to the most stable intermediate.

(i)

Interpretation Introduction

Interpretation:

The product of the given reaction is has be given.

Concept Introduction:

Aromatic five-membered heterocyclic compounds undergo electrophilic aromatic substitution reactions preferentially at 2-position. The intermediate obtained by adding a substituent to this position is more stable than the intermediate obtained by adding a substituent to C-3 position.