Chapter 18, Problem 62P

(a)

Interpretation Introduction

Interpretation: The product of Perkin condensation has to be written

Concept introduction: For the given condensation reactions,

In first case, acetic anhydride is treated with a base and a proton is abstracted.  The enolate ion thus formed attacks carbonyl carbon of benzaldehyde.  Loss of water molecule results in the formation of the product of Perkin condensation.

In second case, water is added to the product of Perkin condensation and it causes hydrolysis of the ester to form an acid.

In third case, diethyl malonate is treated with a base and enolate ion is formed.  Enolate ion attacks a molecule of benzaldehyde and forms an intermediate species.  Loss of a water molecule results in the formation of the product of Knoevenagel reaction.

In fourth case, the product of Knoevenagel reaction on acidic hydrolysis gives carboxylic acid and on heating undergoes decarboxylation.

(b)

Interpretation Introduction

Interpretation: The compound formed after addition of water to the product of Perkin condensation has to be written.

Concept introduction: For the given condensation reactions,

In first case, acetic anhydride is treated with a base and a proton is abstracted.  The enolate ion thus formed attacks carbonyl carbon of benzaldehyde.  Loss of water molecule results in the formation of the product of Perkin condensation.

In second case, water is added to the product of Perkin condensation and it causes hydrolysis of the ester to form an acid.

In third case, diethyl malonate is treated with a base and enolate ion is formed.  Enolate ion attacks a molecule of benzaldehyde and forms an intermediate species.  Loss of a water molecule results in the formation of the product of Knoevenagel reaction.

In fourth case, the product of Knoevenagel reaction on acidic hydrolysis gives carboxylic acid and on heating undergoes decarboxylation.

(c)

Interpretation Introduction

Interpretation: The product of Knoevenagal condensation has to be written

Concept introduction: For the given condensation reactions,

In first case, acetic anhydride is treated with a base and a proton is abstracted.  The enolate ion thus formed attacks carbonyl carbon of benzaldehyde.  Loss of water molecule results in the formation of the product of Perkin condensation.

In second case, water is added to the product of Perkin condensation and it causes hydrolysis of the ester to form an acid.

In third case, diethyl malonate is treated with a base and enolate ion is formed.  Enolate ion attacks a molecule of benzaldehyde and forms an intermediate species.  Loss of a water molecule results in the formation of the product of Knoevenagel reaction.

In fourth case, the product of Knoevenagel reaction on acidic hydrolysis gives carboxylic acid and on heating undergoes decarboxylation.

(d)

Interpretation Introduction

Interpretation: A compound formed after product of Perkin condensation is heated in an acidic medium has to be written

Concept introduction: For the given condensation reactions,

In first case, acetic anhydride is treated with a base and a proton is abstracted.  The enolate ion thus formed attacks carbonyl carbon of benzaldehyde.  Loss of water molecule results in the formation of the product of Perkin condensation.

In second case, water is added to the product of Perkin condensation and it causes hydrolysis of the ester to form an acid.

In third case, diethyl malonate is treated with a base and enolate ion is formed.  Enolate ion attacks a molecule of benzaldehyde and forms an intermediate species.  Loss of a water molecule results in the formation of the product of Knoevenagel reaction.

In fourth case, the product of Knoevenagel reaction on acidic hydrolysis gives carboxylic acid and on heating undergoes decarboxylation.