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

16. Conjugated Systems

Allylic Halogenation

Organic Chemistry

16. Conjugated Systems

Allylic Halogenation

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5:01 minutes

Problem 13c

Textbook Question

Show how you might synthesize the following compounds starting with bromobenzene, and alkyl or alkenyl halides of four carbon atoms or fewer.
c. dec-5-ene

Verified step by step guidance

Step 1: Begin with bromobenzene as the starting material. Perform a Grignard reaction by reacting bromobenzene with magnesium (Mg) in dry ether to form phenylmagnesium bromide (a Grignard reagent). This will allow the phenyl group to act as a nucleophile in subsequent steps.

Step 2: To introduce the alkyl chain, react phenylmagnesium bromide with 1-bromobutane (an alkyl halide with four carbon atoms). This reaction will result in the formation of butylbenzene through a nucleophilic substitution mechanism.

Step 3: Perform a Friedel-Crafts alkylation on butylbenzene to extend the carbon chain. Use an alkyl halide such as 1-bromo-2-butene (a four-carbon alkenyl halide) in the presence of a Lewis acid catalyst like AlCl₃. This will introduce a double bond and form a longer alkyl chain attached to the benzene ring.

Step 4: Hydrogenate the benzene ring selectively to remove aromaticity and form a cyclohexane derivative. Use a catalyst such as Pd/C under hydrogen gas (H₂) to achieve this transformation.

Step 5: Perform a dehydrohalogenation reaction to form dec-5-ene. Use a strong base such as KOH or NaOH in an alcohol solvent to eliminate a halogen atom and form the desired alkene structure.

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Key Concepts

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

Electrophilic Aromatic Substitution

Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. In the context of synthesizing compounds from bromobenzene, understanding EAS is crucial as it allows for the introduction of various substituents onto the benzene ring, which can then be further manipulated to create desired products like dec-5-ene.

Alkylation Reactions

Alkylation reactions involve the introduction of an alkyl group into a molecule, often through nucleophilic substitution or EAS. When synthesizing dec-5-ene, alkyl halides can be used to add carbon chains to the aromatic system or to create alkenes. Recognizing how to effectively use alkyl halides in these reactions is essential for constructing the target compound.

Elimination Reactions

Elimination reactions are processes where two atoms or groups are removed from a molecule, resulting in the formation of a double bond. In the synthesis of dec-5-ene, elimination reactions can be employed after alkylation to generate the alkene from a saturated precursor. Understanding the conditions and mechanisms of elimination is vital for achieving the desired unsaturation in the final product.

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Related Practice

Textbook Question

Show how the reaction of an allylic halide with a Grignard reagent might be used to synthesize the following hydrocarbons.

a. 5-methylhex-1-ene

Textbook Question

Show how the reaction of an allylic halide with a Grignard reagent might be used to synthesize the following hydrocarbons.

b. 2,5,5-trimethylhept-2-ene

Textbook Question

When Br2 is added to buta-1,3-diene at –15 °C, the product mixture contains 60% of product A and 40% of product B. When the same reaction takes place at 60 °C, the product ratio is 10% A and 90% B.

a. Propose structures for products A and B. (Hint: In many cases, an allylic carbocation is more stable than a bromonium ion.)

b. Propose a mechanism to account for formation of both A and B.

c. Show why A predominates at –15 °C and B predominates at 60 °C.

Textbook Question

A student was studying terpene synthesis, and she wanted to make the compound shown here. First she converted 3-bromo-6-methylcyclohexene to alcohol A. She heated alcohol A with sulfuric acid and purified one of the components (compound B) from the resulting mixture. Compound B has the correct molecular formula for the desired product.

a. Suggest how 3-bromo-6-methylcyclohexene might be converted to alcohol A.

Textbook Question

Predict the products of the following reactions.

(g) 1-(bromomethyl)-2-methylcyclopentene, heated in methanol

Textbook Question

Show how the reaction of an allylic halide with a Grignard reagent might be used to synthesize the following hydrocarbons.

a. 5-methylhex-1-ene

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