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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1:20 minutes

Problem 38

Textbook Question

When HCl was used for the attempted dehydration reaction shown, a reaction occurred, but none of the desired product was formed. Suggest the identity of the actual product obtained.

Verified step by step guidance

Step 1: Begin by analyzing the dehydration reaction. Dehydration reactions typically involve the removal of a water molecule from an alcohol to form an alkene. In this case, HCl is used as the acid catalyst, which can protonate the alcohol group.

Step 2: Consider the mechanism of the reaction. When HCl is added, the hydroxyl group (-OH) of the alcohol is protonated to form a good leaving group, water (H₂O). This step is crucial for the formation of a carbocation intermediate.

Step 3: Evaluate the stability of the carbocation intermediate formed after the departure of water. Carbocation stability is influenced by factors such as hyperconjugation and resonance. If the carbocation can rearrange to a more stable form, it will do so.

Step 4: Recognize that HCl introduces chloride ions (Cl⁻) into the reaction mixture. These chloride ions can act as nucleophiles and attack the carbocation, leading to the formation of a substitution product (an alkyl chloride) instead of the desired alkene.

Step 5: Conclude that the actual product obtained is likely an alkyl chloride, formed via nucleophilic attack by Cl⁻ on the carbocation intermediate. This substitution reaction competes with the intended elimination reaction, preventing the formation of the desired alkene.

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Key Concepts

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

Dehydration Reactions

Dehydration reactions involve the removal of a water molecule from a compound, typically resulting in the formation of a double bond or a cyclic structure. In organic chemistry, these reactions are crucial for synthesizing alkenes from alcohols. Understanding the mechanism and conditions under which dehydration occurs is essential for predicting the products formed.

Acid-Catalyzed Reactions

Acid-catalyzed reactions utilize acids, such as HCl, to facilitate the transformation of reactants into products. In dehydration reactions, the acid protonates the alcohol, making it a better leaving group. This concept is vital for understanding how the presence of an acid can influence the reaction pathway and the products formed, including potential side reactions.

Carbocation Stability

Carbocation stability is a key factor in determining the outcome of many organic reactions, including dehydration. Carbocations are positively charged carbon species that can rearrange or react further based on their stability, which is influenced by factors such as alkyl substitution and resonance. Recognizing the stability of potential carbocations helps predict the actual products formed in reactions, especially when the desired product is not obtained.

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