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

10. Addition Reactions

Alkyne Hydrohalogenation

Organic Chemistry

10. Addition Reactions

Alkyne Hydrohalogenation

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3:01 minutes

Problem 29a,b,c

Textbook Question

Using hex-1-ene as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.)
a. 1,2-dibromohexane
b. hex-1-yne
c. 2,2-dibromohexane

Verified step by step guidance

Step 1: To synthesize 1,2-dibromohexane from hex-1-ene, perform an electrophilic addition reaction with bromine (Br₂) in an inert solvent like CCl₄. This reaction adds bromine across the double bond of hex-1-ene, resulting in 1,2-dibromohexane.

Step 2: To synthesize hex-1-yne from hex-1-ene, first convert hex-1-ene into 1,2-dibromohexane using the method described in Step 1. Then, perform a double dehydrohalogenation reaction using a strong base like sodium amide (NaNH₂) in liquid ammonia. This reaction removes two equivalents of HBr, forming the triple bond and yielding hex-1-yne.

Step 3: To synthesize 2,2-dibromohexane from hex-1-ene, first perform a hydrohalogenation reaction with HBr in the presence of peroxides (ROOR). This reaction follows the anti-Markovnikov rule, resulting in the formation of 1-bromohexane.

Step 4: Next, react 1-bromohexane with bromine (Br₂) in the presence of light or heat (a radical bromination reaction). This introduces a bromine atom at the carbon adjacent to the existing bromine, forming 2,2-dibromohexane.

Step 5: Verify the structures of all synthesized compounds to ensure the correct functional groups and positions of substituents are achieved. Use spectroscopic techniques like NMR or IR for confirmation if needed.

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Key Concepts

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

Electrophilic Addition Reactions

Electrophilic addition reactions are fundamental in organic chemistry, particularly for alkenes like hex-1-ene. In these reactions, an electrophile reacts with the double bond of the alkene, leading to the formation of a more saturated compound. For example, adding bromine to hex-1-ene results in 1,2-dibromohexane, showcasing how alkenes can be transformed into haloalkanes.

Alkyne Synthesis

Alkynes, characterized by a carbon-carbon triple bond, can be synthesized from alkenes through elimination reactions. For instance, converting hex-1-ene to hex-1-yne typically involves a dehydrohalogenation process, where a halogen and a hydrogen atom are removed from adjacent carbon atoms. Understanding this transformation is crucial for synthesizing compounds with triple bonds.

Rearrangement Reactions

Rearrangement reactions involve the reorganization of atoms within a molecule to form a new structure, often leading to more stable configurations. In the case of synthesizing 2,2-dibromohexane, a rearrangement may occur after the initial addition of bromine to hex-1-ene, allowing for the formation of a more substituted and stable product. Recognizing these pathways is essential for predicting the outcomes of synthetic routes.

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