Chapter 19, Problem 19.18P

(a)

Interpretation Introduction

Interpretation:

The product of the aldol reaction of the given compound and the $\text{α,β}$-unsaturated aldehyde or ketone formed from dehydration of the aldol product has to be drawn.

Concept introduction:

Aldol reaction is an addition reaction of aldehydes and ketones. Aldol reaction is a reversible reaction and occurs in the presence of a strong base like sodium hydroxide. One molecule (aldehyde or ketone) acts a nucleophile and attacks the electrophilic carbon center of the other molecule to give the addition product. The product is named $\beta$-hydroxy aldehyde if two aldehydes combine and $\beta$-hydroxy ketone if two ketones combine.

Explanation of Solution

The aldol reaction product for the given compound has to be drawn.

The aldol reaction yield a $\beta$-hydroxy aldehyde as the product and on dehydration, water is eliminated and the product is formed.

Base abstracts a proton from the $\alpha$ carbon atom of aldehyde. Enolate anion is formed after abstraction of $\alpha$ proton from aldehyde molecule. Enolate ion attacks on the carbonyl carbon of the other molecule of aldehyde. The species formed in this step abstracts proton from water to give the $\beta$-hydroxy aldehyde. Loss of water molecule from the aldol product produces the product given below.

(b)

Interpretation Introduction

Interpretation:

The product of the aldol reaction of the given compound and the $\text{α,β}$-unsaturated aldehyde or ketone formed from dehydration of the aldol product has to be drawn.

Concept introduction:

Aldol reaction is an addition reaction of aldehydes and ketones. Aldol reaction is a reversible reaction and occurs in the presence of a strong base like sodium hydroxide. One molecule (aldehyde or ketone) acts a nucleophile and attacks the electrophilic carbon center of the other molecule to give the addition product. The product is named $\beta$-hydroxy aldehyde if two aldehydes combine and $\beta$-hydroxy ketone if two ketones combine.

Explanation of Solution

The aldol reaction product for the given compound has to be drawn.

The aldol reaction yield a $\beta$-hydroxy ketone as the product and on dehydration, water is eliminated and the product is formed.

Base abstracts a proton from the $\alpha$ carbon atom of ketone. Enolate anion is formed after abstraction of $\alpha$ proton from ketone molecule. Enolate ion attacks on the carbonyl carbon of the other molecule of ketone. The species formed in this step abstracts proton from water to give the $\beta$-hydroxy ketone. Loss of water molecule from the aldol product produces the product given below.

(c)

Interpretation Introduction

Interpretation:

The product of the aldol reaction of the given compound and the $\text{α,β}$-unsaturated aldehyde or ketone formed from dehydration of the aldol product has to be drawn.

Concept introduction:

Aldol reaction is an addition reaction of aldehydes and ketones. Aldol reaction is a reversible reaction and occurs in the presence of a strong base like sodium hydroxide. One molecule (aldehyde or ketone) acts a nucleophile and attacks the electrophilic carbon center of the other molecule to give the addition product. The product is named $\beta$-hydroxy aldehyde if two aldehydes combine and $\beta$-hydroxy ketone if two ketones combine.

Explanation of Solution

The aldol reaction product for the given compound has to be drawn.

The aldol reaction yield a $\beta$-hydroxy ketone as the product and on dehydration, water is eliminated and the product is formed.

Base abstracts a proton from the $\alpha$ carbon atom of the ketone. Enolate anion is formed after abstraction of $\alpha$ proton from ketone molecule. Enolate ion attacks on the carbonyl carbon of the same molecule. The species formed in above step abstracts proton from water to give the $\beta$-hydroxy ketone. Loss of water molecule from the aldol product produces the product given below.