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

8. Elimination Reactions

SN1 SN2 E1 E2 Chart (Big Daddy Flowchart)

Organic Chemistry

8. Elimination Reactions

SN1 SN2 E1 E2 Chart (Big Daddy Flowchart)

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3:32 minutes

Problem 43a

Textbook Question

Suggest an appropriate base to synthesize the alkene as the major product from the starting haloalkane.
(a)

Verified step by step guidance

Step 1: Understand the reaction type. The synthesis of an alkene from a haloalkane typically involves an elimination reaction (E2 or E1 mechanism). The choice of base is crucial for favoring the elimination pathway over substitution.

Step 2: Analyze the structure of the haloalkane. Determine whether the haloalkane is primary, secondary, or tertiary. This will influence the mechanism (E2 or E1) and the strength of the base required.

Step 3: Consider steric hindrance. If the haloalkane is bulky (e.g., tertiary), a strong, bulky base like potassium tert-butoxide (K⁺[CH₃]₃CO⁻) is often used to favor elimination and minimize substitution.

Step 4: Evaluate the reaction conditions. Strong bases such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) can be used for E2 elimination, while weaker bases may favor E1 elimination under acidic conditions.

Step 5: Select the base based on regioselectivity. If the goal is to form the more substituted alkene (Zaitsev product), use a strong base like NaOH or KOH. If the goal is to form the less substituted alkene (Hofmann product), use a bulky base like potassium tert-butoxide.

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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 leaving group and a hydrogen atom from adjacent carbon atoms, resulting in the formation of a double bond. In the context of haloalkanes, these reactions can lead to the synthesis of alkenes. The most common types of elimination reactions are E1 and E2, which differ in their mechanisms and conditions.

Strong Bases

Strong bases are essential for promoting elimination reactions, particularly E2 mechanisms, where a strong base abstracts a proton while the leaving group departs. Common strong bases include sodium hydroxide (NaOH), potassium tert-butoxide (KOtBu), and sodium ethoxide (NaOEt). The choice of base can influence the regioselectivity and stereochemistry of the resulting alkene.

Zaitsev's Rule

Zaitsev's Rule states that in elimination reactions, the more substituted alkene is typically the major product. This is due to the stability of more substituted alkenes, which are favored thermodynamically. Understanding this rule helps in predicting the outcome of reactions involving haloalkanes and the choice of base can also affect which alkene is formed.

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