Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

25. Condensation Chemistry

Aldol Condensation

Organic Chemistry

25. Condensation Chemistry

Aldol Condensation

Previous problemNext problem

2:54 minutes

Problem 19a

Textbook Question

Give the expected products for the aldol condensations of (a) propanal.

Verified step by step guidance

Step 1: Understand the aldol condensation reaction. Aldol condensation involves the reaction of an enolate ion (formed from an aldehyde or ketone) with another molecule of aldehyde or ketone, followed by dehydration to form an α,β-unsaturated carbonyl compound.

Step 2: Identify the reactant. In this case, the reactant is propanal (CH₃CH₂CHO), which contains an α-hydrogen necessary for enolate formation.

Step 3: Generate the enolate ion. Under basic conditions, the α-hydrogen of propanal is deprotonated to form the enolate ion: \( \text{CH}_3\text{CH}=\text{CH}^- \).

Step 4: Perform the nucleophilic attack. The enolate ion acts as a nucleophile and attacks the carbonyl carbon of another molecule of propanal, forming a β-hydroxy aldehyde intermediate: \( \text{CH}_3\text{CH}(\text{OH})\text{CH}_2\text{CHO} \).

Step 5: Dehydrate the β-hydroxy aldehyde. Under heating or continued basic conditions, the β-hydroxy aldehyde undergoes elimination of water to form the α,β-unsaturated aldehyde product: \( \text{CH}_3\text{CH}=\text{CHCHO} \) (crotonaldehyde).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Aldol Condensation

Aldol condensation is a reaction between aldehydes or ketones that contain at least one alpha-hydrogen. In this process, an enolate ion is formed from one carbonyl compound, which then attacks the carbonyl carbon of another molecule, leading to the formation of a beta-hydroxy aldehyde or ketone. This intermediate can further dehydrate to yield an alpha, beta-unsaturated carbonyl compound.

Propanal Structure

Propanal, also known as propionaldehyde, is a three-carbon aldehyde with the chemical formula C3H6O. Its structure consists of a carbon chain with a terminal carbonyl group (C=O) and two additional carbon atoms. Understanding the structure of propanal is crucial for predicting the products of its aldol condensation, as the presence of alpha-hydrogens on the second carbon allows for enolate formation.

Enolate Ion Formation

Enolate ions are formed when a carbonyl compound undergoes deprotonation at the alpha-carbon, resulting in a resonance-stabilized anion. This ion is a key intermediate in aldol reactions, as it acts as a nucleophile that can attack another carbonyl compound. The ability to form enolates is essential for understanding the reactivity of aldehydes and ketones in aldol condensations.

Watch next

Master General Features with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Predict the products of aldol condensation, followed by dehydration, of the following ketones and aldehydes.

(b) acetophenone

Textbook Question

Predict the products of aldol condensation, followed by dehydration, of the following ketones and aldehydes.

(a) butyraldehyde

Textbook Question

Give the expected products for the aldol condensations of (c) pentan-3-one.

Textbook Question

Give the expected products for the aldol condensations of (b) phenylacetaldehyde.

Textbook Question

The Knoevenagel condensation is a special case of the aldol condensation in which an active methylene compound reacts with an aldehyde or ketone, in the presence of a secondary amine as a basic catalyst, to produce a new C=C. Show the starting materials that made each of these by a Knoevenagel condensation.

(b)

Textbook Question

(c)

Textbook Question

Propose a mechanism for the aldol condensation of cyclohexanone. Do you expect the equilibrium to favor the reactant or the product?

Textbook Question

Propose a complete mechanism for the acid-catalyzed aldol condensation of acetone.

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap