Question 1

Under basic conditions, the Aldol reaction is reversible, but dehydration is not.What is the reason for this difference in reactivity?

Accepted Answer

A) The initial Aldol product is an alkoxide, so the reaction is not energetically downhill in either direction. 
B) The initial Aldol product is an alkoxide, so the reaction is energetically downhill going toward the product. 
C) The initial Aldol product is an alkoxide, so the reaction is energetically downhill going toward the starting materials. 
D) Water is a stable molecule. 
A) The initial Aldol product is an alkoxide, so the reaction is not energetically downhill in either direction. 
B) The initial Aldol product is an alkoxide, so the reaction is energetically downhill going toward the product. 
C) The initial Aldol product is an alkoxide, so the reaction is energetically downhill going toward the starting materials. 
D) Water is a stable molecule. A

Question 2

Would this crossed Aldol reaction work well? Why or why not?

Accepted Answer

A) Yes, the diketone is significantly more acidic, so this enolate can be formed selectively. 
B) Yes, the aldehyde is significantly more acidic, so this enolate can be formed selectively. 
C) No, the aldehyde is significantly more acidic, so this enolate cannot be formed selectively. 
D) No, the diketone is significantly more acidic, so this enolate cannot be formed selectively. 
A) Yes, the diketone is significantly more acidic, so this enolate can be formed selectively. 
B) Yes, the aldehyde is significantly more acidic, so this enolate can be formed selectively. 
C) No, the aldehyde is significantly more acidic, so this enolate cannot be formed selectively. 
D) No, the diketone is significantly more acidic, so this enolate cannot be formed selectively. A

Question 3

What is the Aldol addition product formed from the reaction of acetone, (CH3)2CO, with itself?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV A

Question 4

What is the Aldol addition product formed from reaction of the following compound with itself?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 5

The b-hydroxy carbonyl product of an Aldol reaction is oftentimes not the final isolated product; what is the explanation for this result?

Accepted Answer

A) It undergoes elimination, since water is a good leaving group. 
B) The hydroxy group is oxidized to a carbonyl. 
C) The hydroxy group reacts with the carbonyl to form a ketal. 
D) Hydroxide is eliminated via an enolate intermediate. 
A) It undergoes elimination, since water is a good leaving group. 
B) The hydroxy group is oxidized to a carbonyl. 
C) The hydroxy group reacts with the carbonyl to form a ketal. 
D) Hydroxide is eliminated via an enolate intermediate.

Question 6

The following reaction is an example of what type of reaction?

Accepted Answer

A) Claisen condensation 
B) Mixed Aldol reaction 
C) Robinson annulation 
D) Dieckmann condensation 
A) Claisen condensation 
B) Mixed Aldol reaction 
C) Robinson annulation 
D) Dieckmann condensation

Question 7

What cyclic product is formed in the intramolecular Aldol condensation when the following compound is treated with aqueous NaOH?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 8

What is the general name for the class of products formed in an Aldol condensation reaction?

Accepted Answer

A) b,g-Unsaturated carbonyl compound 
B) a,b-Unsaturated carbonyl compound 
C) a,g-Unsaturated carbonyl compound 
D) b-Hydroxy carbonyl compound 
A) b,g-Unsaturated carbonyl compound 
B) a,b-Unsaturated carbonyl compound 
C) a,g-Unsaturated carbonyl compound 
D) b-Hydroxy carbonyl compound

Question 9

Which of the following bicyclic ring systems can be prepared by an intermolecular Robinson annulation?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 10

There are several variations of the Aldol reaction.Which of the following types of reactants leads to only one possible product with the Aldol condensation reaction?

Accepted Answer

A) Two different aldehydes with a-hydrogens are able to form a single aldol condensation product. 
B) Two different ketones with a-hydrogens are able to form a single aldol condensation product. 
C) Any aldehyde and ketone mixed together can react to form a single condensation product. 
D) Any pair of aldehyde or ketone reactants where one of the reactants has no a-hydrogens will lead to a single aldol product. 
A) Two different aldehydes with a-hydrogens are able to form a single aldol condensation product. 
B) Two different ketones with a-hydrogens are able to form a single aldol condensation product. 
C) Any aldehyde and ketone mixed together can react to form a single condensation product. 
D) Any pair of aldehyde or ketone reactants where one of the reactants has no a-hydrogens will lead to a single aldol product.

Question 11

Of the carbonyl compounds; (1) benzaldehyde, (2) acetophenone and (3) dicyclohexyl ketone, which compound has noa-hydrogens?

Accepted Answer

A) Benzaldehyde 
B) Acetophenone 
C) Acetone 
D) All of these compounds contain a-hydrogens. 
A) Benzaldehyde 
B) Acetophenone 
C) Acetone 
D) All of these compounds contain a-hydrogens.

Question 12

In the correct order, what are the three steps in the mechanism of an Aldol reaction?

Accepted Answer

A) Protonation, enolate formation, nucleophilic addition 
B) Enolate formation, protonation, nucleophilic addition 
C) Enolate formation, nucleophilic addition, protonation 
D) Nucleophilic addition, enolate formation, protonation 
A) Protonation, enolate formation, nucleophilic addition 
B) Enolate formation, protonation, nucleophilic addition 
C) Enolate formation, nucleophilic addition, protonation 
D) Nucleophilic addition, enolate formation, protonation

Question 13

Which is the unsaturated carbonyl compound formed in the dehydration of the following b-hydroxy carbonyl compound?

Accepted Answer

A) I 
B) II 
C) I and II 
D) None of the choices 
A) I 
B) II 
C) I and II 
D) None of the choices

Question 14

What is the cyclic product formed in the intramolecular Aldol condensation when the following compound is treated with aqueous NaOH?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 15

Why is the Aldol reaction often called an Aldol condensation?

Accepted Answer

A) The initially formed b-hydroxy carbonyl compound loses a hydroxyl group. 
B) The initially formed b-hydroxy carbonyl compound loses an oxygen atom. 
C) The initially formed b-hydroxy carbonyl compound loses a hydrogen atom. 
D) The initially formed b-hydroxy carbonyl compound loses water. 
A) The initially formed b-hydroxy carbonyl compound loses a hydroxyl group. 
B) The initially formed b-hydroxy carbonyl compound loses an oxygen atom. 
C) The initially formed b-hydroxy carbonyl compound loses a hydrogen atom. 
D) The initially formed b-hydroxy carbonyl compound loses water.

Question 16

When is a crossed Aldol reaction said to be synthetically useful?

Accepted Answer

A) When both carbonyl compounds have a hydrogens 
B) When both carbonyl compounds have no a hydrogens 
C) When one carbonyl compound has no a hydrogens 
D) When one carbonyl compound has no b hydrogens 
A) When both carbonyl compounds have a hydrogens 
B) When both carbonyl compounds have no a hydrogens 
C) When one carbonyl compound has no a hydrogens 
D) When one carbonyl compound has no b hydrogens

Question 17

When is a crossed Claisen reaction between two different esters synthetically useful?

Accepted Answer

A) When only one of the esters has a hydrogen atoms 
B) When both esters have a hydrogen atoms 
C) When only one of the esters has b hydrogen atoms 
D) When both esters lack a hydrogen atoms 
A) When only one of the esters has a hydrogen atoms 
B) When both esters have a hydrogen atoms 
C) When only one of the esters has b hydrogen atoms 
D) When both esters lack a hydrogen atoms

Question 18

Complete this statement: A major difference between the Aldol condensation and the Claisen condensation reactions is that

Accepted Answer

A) the Aldol reaction involves substitution while the Claisen reaction involves addition. 
B) the Aldol reaction is acid catalyzed while the Claisen reaction is base-catalyzed. 
C) the Aldol reaction is base catalyzed while the Claisen reaction requires a full equivalent of base. 
D) the Aldol reaction is base catalyzed while the Claisen reaction is acid-catalyzed. 
A) the Aldol reaction involves substitution while the Claisen reaction involves addition. 
B) the Aldol reaction is acid catalyzed while the Claisen reaction is base-catalyzed. 
C) the Aldol reaction is base catalyzed while the Claisen reaction requires a full equivalent of base. 
D) the Aldol reaction is base catalyzed while the Claisen reaction is acid-catalyzed.

Question 19

Which of the following statements about Aldol reactions with either aldehydes or ketones is true?

Accepted Answer

A) Equilibrium favors the products with aldehydes; equilibrium favors the starting materials with ketones. 
B) Equilibrium favors the starting materials with aldehydes; equilibrium favors the products with ketones. 
C) Equilibrium favors the products with both aldehydes and ketones. 
D) Equilibrium favors the starting materials with both aldehydes and ketones. 
A) Equilibrium favors the products with aldehydes; equilibrium favors the starting materials with ketones. 
B) Equilibrium favors the starting materials with aldehydes; equilibrium favors the products with ketones. 
C) Equilibrium favors the products with both aldehydes and ketones. 
D) Equilibrium favors the starting materials with both aldehydes and ketones.

Question 20

What is an intramolecular Claisen reaction called?

Accepted Answer

A) Michael reaction 
B) Robinson reaction 
C) Hoffman reaction 
D) Dieckmann reaction 
A) Michael reaction 
B) Robinson reaction 
C) Hoffman reaction 
D) Dieckmann reaction

Exam 24: Carbonyl Condensation Reactions

Under basic conditions, the Aldol reaction is reversible, but dehydration is not.What is the reason for this difference in reactivity?

Would this crossed Aldol reaction work well? Why or why not?

What is the Aldol addition product formed from the reaction of acetone, (CH3)2CO, with itself?

What is the Aldol addition product formed from reaction of the following compound with itself?

The b-hydroxy carbonyl product of an Aldol reaction is oftentimes not the final isolated product; what is the explanation for this result?

The following reaction is an example of what type of reaction?

What cyclic product is formed in the intramolecular Aldol condensation when the following compound is treated with aqueous NaOH?

What is the general name for the class of products formed in an Aldol condensation reaction?

Which of the following bicyclic ring systems can be prepared by an intermolecular Robinson annulation?

There are several variations of the Aldol reaction.Which of the following types of reactants leads to only one possible product with the Aldol condensation reaction?

Of the carbonyl compounds; (1) benzaldehyde, (2) acetophenone and (3) dicyclohexyl ketone, which compound has noa-hydrogens?

In the correct order, what are the three steps in the mechanism of an Aldol reaction?

Which is the unsaturated carbonyl compound formed in the dehydration of the following b-hydroxy carbonyl compound?

What is the cyclic product formed in the intramolecular Aldol condensation when the following compound is treated with aqueous NaOH?

Why is the Aldol reaction often called an Aldol condensation?

When is a crossed Aldol reaction said to be synthetically useful?

When is a crossed Claisen reaction between two different esters synthetically useful?

Complete this statement: A major difference between the Aldol condensation and the Claisen condensation reactions is that

Which of the following statements about Aldol reactions with either aldehydes or ketones is true?

What is an intramolecular Claisen reaction called?

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What is the Aldol addition product formed from the reaction of acetone, (CH₃)₂CO, with itself?