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

Previous problemNext problem

6:09 minutes

Problem 56a,b

Textbook Question

Indicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H₂SO₄.
a.
b.

Verified step by step guidance

Step 1: Understand the mechanism of elimination reactions in alcohols. Alcohols undergo elimination reactions to form alkenes when treated with strong acids like H2SO4. This process typically follows the E1 mechanism, which involves the formation of a carbocation intermediate.

Step 2: Consider the stability of the carbocation formed during the reaction. The rate of elimination is influenced by the stability of the carbocation intermediate. More stable carbocations lead to faster elimination reactions.

Step 3: Analyze the structure of each alcohol in the pair. Identify the type of alcohol (primary, secondary, or tertiary) as this affects the stability of the carbocation. Tertiary alcohols generally form more stable carbocations compared to secondary and primary alcohols.

Step 4: Compare the alcohols in each pair based on their ability to form stable carbocations. The alcohol that forms the more stable carbocation will undergo elimination more rapidly.

Step 5: Consider any additional factors such as steric hindrance or resonance that might affect carbocation stability. Resonance can stabilize carbocations, while steric hindrance can slow down the reaction. Use these considerations to make a final comparison between the alcohols in each pair.

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.

Elimination Reactions

Elimination reactions involve the removal of a small molecule from a larger one, typically resulting in the formation of a double bond. In organic chemistry, these reactions often occur with alcohols when treated with strong acids like H2SO4, leading to the formation of alkenes. The rate of elimination can depend on the structure of the alcohol, including factors like steric hindrance and the stability of the resulting alkene.

Alcohol Structure and Stability

The structure of an alcohol significantly influences its reactivity in elimination reactions. Tertiary alcohols generally undergo elimination more readily than primary or secondary alcohols due to the stability of the carbocation intermediate formed during the reaction. The more substituted the alkene product, the more stable it is, which also drives the elimination process.

Role of H2SO4 in Elimination

H2SO4 acts as a strong acid that protonates the hydroxyl group of the alcohol, converting it into a better leaving group. This protonation step is crucial for facilitating the elimination reaction. Additionally, H2SO4 can promote dehydration, where water is removed, leading to the formation of alkenes. The temperature and concentration of H2SO4 can also affect the rate of the elimination reaction.

Watch next

Master General features of acid-catalyzed dehydration. with a bite sized video explanation from Johnny

Start learning