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

E2 Mechanism

Organic Chemistry

8. Elimination Reactions

E2 Mechanism

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4:26 minutes

Problem 35

Textbook Question

When 2-bromopropane is treated with sodium ethoxide, propene is produced. What molecule is lost from 2-bromopropane in this process?

Verified step by step guidance

Step 1: Recognize the type of reaction occurring. This is an elimination reaction (E2 mechanism), where a molecule is lost from the substrate to form a double bond.

Step 2: Identify the substrate, 2-bromopropane, and note that it contains a bromine atom attached to the second carbon of a propane chain.

Step 3: Understand the role of sodium ethoxide (NaOCH₂CH₃). It acts as a strong base, abstracting a proton (H⁺) from a β-carbon (the carbon adjacent to the carbon bonded to bromine).

Step 4: Determine the molecule lost during the reaction. The bromine atom leaves as a bromide ion (Br⁻), and a proton (H⁺) is abstracted from the β-carbon, resulting in the formation of propene (CH₃-CH=CH₂). The lost molecule is HBr (hydrogen bromide).

Step 5: Summarize the process: Sodium ethoxide facilitates the elimination of HBr from 2-bromopropane, leading to the formation of propene via the E2 mechanism.

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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 small molecule from a larger one, resulting in the formation of a double bond. In the case of 2-bromopropane reacting with sodium ethoxide, an elimination reaction occurs, leading to the formation of propene. Understanding the mechanism of elimination is crucial for predicting the products of such reactions.

Leaving Groups

A leaving group is an atom or group that can depart from the parent molecule during a chemical reaction. In the context of 2-bromopropane, the bromine atom acts as a leaving group when the sodium ethoxide facilitates the elimination process. The stability and ability of the leaving group to depart significantly influence the reaction's efficiency.

Base-Induced Elimination

Base-induced elimination refers to the process where a strong base, such as sodium ethoxide, abstracts a proton from a β-carbon, leading to the formation of a double bond. This mechanism is essential in understanding how propene is generated from 2-bromopropane, as the base facilitates the removal of a hydrogen atom alongside the leaving group.

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Related Practice

Textbook Question

a. Explain why 1-bromo-2,2-dimethylpropane has difficulty undergoing both S_N2 and S_N1 reactions.

b. Can it undergo E2 and E1 reactions?

Textbook Question

What is the major elimination product obtained from an E2 reaction of each of the following alkyl halides with hydroxide ion?

Textbook Question

What products will be obtained from the E2 reaction of the following alkyl halides?

Textbook Question

Draw the major product obtained when each of the following alkyl halides undergoes an E2 reaction:

Textbook Question

Justify on a reaction coordinate diagram the fact that a strong base like sodium amide (NaNH₂) results in a faster E2 elimination than does sodium hydroxide (NaOH).

Textbook Question

Practice your electron-pushing skills by drawing a mechanism for the following E2 reactions.

(a)

Textbook Question

Suggest a mechanism for the following elimination reactions.

(c)

Textbook Question

Predict the major product(s) of the following elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(a)

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