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

9. Alkenes and Alkynes

Dehydration Reaction

Organic Chemistry

9. Alkenes and Alkynes

Dehydration Reaction

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3:54 minutes

Problem 54c

Textbook Question

Write a balanced equation for each reaction, showing the major product you expect.
(c)

Verified step by step guidance

Step 1: Analyze the reactant structure. The molecule is a cyclohexane ring with two hydroxyl (-OH) groups attached to adjacent carbons. This is a diol (vicinal diol).

Step 2: Recognize the reaction conditions. The presence of concentrated sulfuric acid (H₂SO₄) and heat suggests a dehydration reaction, where water molecules are eliminated.

Step 3: Understand the mechanism. Under acidic conditions, one hydroxyl group is protonated, forming a good leaving group (water). The adjacent hydroxyl group can then lose a proton, leading to the formation of a carbocation intermediate.

Step 4: Predict the major product. The carbocation intermediate undergoes rearrangement or stabilization, followed by elimination of a proton from a neighboring carbon to form a double bond. This results in the formation of an alkene. In this case, the major product is likely cyclohexene.

Step 5: Write the balanced equation. The reaction eliminates two molecules of water (H₂O) from the diol, forming cyclohexene as the major product. The balanced equation is:

C 6 H 12 O 2 \to C 6 H 10 + 2 H 2 O

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Key Concepts

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

Dehydration Reaction

A dehydration reaction involves the removal of water (H2O) from a molecule, often resulting in the formation of a double bond or a ring structure. In organic chemistry, this process is commonly facilitated by heat and an acid catalyst, such as sulfuric acid, which helps to protonate the hydroxyl groups, making them better leaving groups.

Acid-Catalyzed Reactions

Acid-catalyzed reactions utilize an acid to increase the rate of a chemical reaction. In the context of dehydration, sulfuric acid donates protons to the hydroxyl groups, enhancing their ability to leave as water. This mechanism is crucial for driving the reaction forward and achieving the desired product.

Major Product Formation

In organic reactions, the major product is the most stable or predominant product formed under the given reaction conditions. Factors such as sterics, electronics, and the stability of intermediates influence which product is favored. Understanding these factors is essential for predicting the outcome of the dehydration reaction shown in the question.

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Related Practice

Textbook Question

Propose a mechanism for each reaction.

(c)

Textbook Question

Propose a mechanism for each reaction.

(a)

Textbook Question

Propose mechanisms for the following reactions. In most cases, more products are formed than are shown here. You only need to explain the formation of the products shown, however.

(b)

Textbook Question

Write a balanced equation for each reaction, showing the major product you expect.

(a)

Textbook Question

Show the product(s) you expect from dehydration of the following alcohols when they are heated in sulfuric or phosphoric acid. In each case, use a mechanism to show how the products are formed.

(c)

Textbook Question

Write a mechanism that explains the formation of the following product. In your mechanism, explain the cause of the rearrangement, and explain the failure to form the Zaitsev product.

Textbook Question

Predict the products of the sulfuric acid-catalyzed dehydration of the following alcohols. When more than one product is expected, label the major and minor products.

(d) 1-isopropylcyclohexanol

(e) 2-methylcyclohexanol

Textbook Question

Propose mechanisms for the following reactions. Additional products may be formed, but your mechanism only needs to explain the products shown.

(b)

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