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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3:23 minutes

Problem 41a

Textbook Question

Identify the alcohol(s) that would produce the following alkenes under the given conditions.
(a)

Verified step by step guidance

Step 1: Understand the reaction mechanism. The conversion of alcohols to alkenes typically occurs through an elimination reaction, such as E1 or E2, depending on the conditions. In acidic conditions, the reaction often proceeds via the E1 mechanism, involving protonation of the alcohol and formation of a carbocation intermediate.

Step 2: Analyze the structure of the given alkene. Identify the position of the double bond and the carbon atoms involved. This will help determine the possible alcohol precursors.

Step 3: Consider the regioselectivity and stereoselectivity of the elimination reaction. For example, Zaitsev's rule states that the most substituted alkene is usually favored in elimination reactions. This can help predict which alcohols are likely to produce the given alkene.

Step 4: Identify the alcohol(s) that could lead to the given alkene. For each alcohol, consider the position of the hydroxyl group (-OH) and how elimination would occur to form the double bond. Ensure that the elimination follows the correct mechanism (E1 or E2) under the given conditions.

Step 5: Verify the feasibility of the reaction. Check for factors such as carbocation stability (in E1 reactions) or the presence of a strong base (in E2 reactions) to confirm that the identified alcohol(s) can indeed produce the given alkene.

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Key Concepts

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

Alcohol Dehydration

Alcohol dehydration is a chemical reaction where an alcohol loses a water molecule to form an alkene. This process typically occurs under acidic conditions, where the hydroxyl group of the alcohol is protonated, making it a better leaving group. The resulting carbocation can then undergo elimination of a proton, leading to the formation of a double bond in the alkene.

Zaitsev's Rule

Zaitsev's Rule states that in elimination reactions, the more substituted alkene is generally the major product. This is because more substituted alkenes are more stable due to hyperconjugation and the inductive effect. Understanding this rule helps predict which alkene will be favored when multiple elimination products are possible from a given alcohol.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In the context of alcohol dehydration, regioselectivity is influenced by the stability of the carbocation intermediate and the position of the double bond in the resulting alkene. Recognizing regioselectivity is crucial for determining the correct alcohol that will produce the desired alkene.

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