Concept explainers
(a)
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
(b)
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: 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: 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.
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Organic Chemistry
- There are other condensation reactions similar to the aldol and Claisen condensations: a. The Perkin condensation is the condensation of an aromatic aldehyde and acetic anhydride. Draw the product obtained from the following Perkin condensationarrow_forwardWhich statement describes why aldol reactions with ketones are low yielding? A.Ketones do not have acidic protons. B.Ketones are too electron poor at the carbonyl carbon. C.Ketones can attack other ketones well but perform poorly in self-condensations. D.The product of a ketone addition to a ketone has considerable steric strain.arrow_forward9. What type of product results when an aldehyde undergoes an aldol reaction with heat? a. conjugated diene b. B-hydroxy aldehyde c. a,ß-unsaturated aldehyde d. B-ketoesterarrow_forward
- $7. What is the major product of this intramolecular aldol condensation reaction? HO H. d. H.arrow_forwardWhat is the general name for the reaction product formed in an aldol addition reaction? O 1) a-hydroxy carbonyl compound 2) a.ß-hydroxy carbonyl compound O3) Y-hydroxy carbonyl compound 4) B-hydroxy carbonyl compoundarrow_forwardWhat functional group is formed as the final product of an aldol condensation? A. B-hydroxycarbonyl В. a,B-unsaturated carbonyl C. enol D. enolatearrow_forward
- 4. Draw the aldehydes needed to prepare the compound below by an aldol reaction. OH CHO From: ogynu abmu and Voarrow_forward7. When the following ketone is treated with sodium hydroxide, two different enolates can form. a. Draw the two enolates, including an arrow pushing mechanism for their formation and any relevant resonance structures. NaOH b. Which enolate is favored when using sodium hydroxide as the base? Explain. c. Predict the product of the reaction and include an arrow-pushing mechanism. 1. NaOH 2. Brarrow_forwardGive the reaction mechanism for the following: a. Aldol condensation b. Claisen condensation c. Dehydration of aldol i. in basic medium ii. in acidic mediumarrow_forward
- Explain how the Knoevenagel condensation is a variant of the aldol condensation.Draw reaction schemes to answer the question.arrow_forwardUsing cyclopentanone as the reactant, show the product of a. acid-catalyzed keto–enol interconversion. b. an aldol addition. c. an aldol condensation.arrow_forwardWhy is the Aldol reaction often called an Aldol condensation? 1) The initially formed b-hydroxy carbonyl compound loses an oxygen atom 2) The initially formed b-hydroxy carbonyl compound loses a hydrogen atom 3) The initially formed b-hydroxy carbonyl compound loses water 4) The initially formed b-hydroxy carbonyl compound loses a hydroxyl grouparrow_forward
- Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning