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

Acetylide

Organic Chemistry

9. Alkenes and Alkynes

Acetylide

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5:01 minutes

Problem 13a(3)

Textbook Question

Show how the following compounds can be prepared, using ethyne as one of the starting materials:
3. 2-methyl-3-hexyn-2-ol

Verified step by step guidance

Step 1: Start with ethyne (C₂H₂) as the base molecule. Ethyne is a simple alkyne with a triple bond between two carbon atoms. The goal is to build the desired structure step by step by adding the necessary groups.

Step 2: Perform a hydroboration-oxidation reaction to convert ethyne into an aldehyde. Use reagents such as disiamylborane (R₂BH) followed by hydrogen peroxide (H₂O₂) and sodium hydroxide (NaOH). This will yield acetaldehyde (CH₃CHO).

Step 3: Perform an aldol addition reaction to extend the carbon chain. React acetaldehyde with a suitable aldehyde or ketone (e.g., butanal) in the presence of a base (e.g., NaOH) to form a β-hydroxy ketone intermediate. This step helps in building the hexyn backbone.

Step 4: Introduce the triple bond at the desired position. Use a strong base (e.g., NaNH₂) to deprotonate the β-hydroxy ketone intermediate, followed by elimination to form the alkyne. This will yield 2-methyl-3-hexyne.

Step 5: Perform a hydration reaction to introduce the hydroxyl group (-OH) at the desired position. Use reagents such as HgSO₄ and H₂SO₄ to hydrate the alkyne selectively, forming 2-methyl-3-hexyn-2-ol as the final product.

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Key Concepts

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

Ethyne as a Building Block

Ethyne, also known as acetylene, is a simple alkyne that serves as a versatile building block in organic synthesis. Its triple bond allows for various reactions, including addition reactions with electrophiles, which can lead to the formation of more complex molecules. Understanding how to manipulate ethyne is crucial for synthesizing target compounds like 2-methyl-3-hexyn-2-ol.

Alkyne Reactions

Alkynes undergo a variety of reactions, including hydrohalogenation, hydration, and alkylation. These reactions can be used to introduce functional groups or extend carbon chains. For the synthesis of 2-methyl-3-hexyn-2-ol, knowledge of how to perform these reactions with ethyne is essential to achieve the desired structure and functionalization.

Functional Group Interconversion

Functional group interconversion involves transforming one functional group into another, which is often necessary in organic synthesis. In the case of 2-methyl-3-hexyn-2-ol, converting an alkyne to an alcohol through hydration is a key step. Understanding the mechanisms and conditions for these transformations is vital for successfully preparing the target compound.

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Related Practice

Textbook Question

Suggest reagents you might use to generate the product from the given reactant.

(b)

Textbook Question

A chemist is planning to synthesize 3-octyne by adding 1-bromobutane to the product obtained from the reaction of 1-butyne with sodium amide. Unfortunately, however, he forgot to order 1-butyne. How else can he prepare 3-octyne?

Textbook Question

Draw the product of each of the following reactions:

Textbook Question

Show how you might synthesize the following compounds, using acetylene and any suitable alkyl halides as your starting materials. If the compound given cannot be synthesized by this method, explain why.

d. 4-methylhex-2-yne

e. 5-methylhex-2-yne

f. cyclodecyne

Textbook Question

Why is a cumulated diene not formed in the reaction shown above?

Textbook Question

A chemist attempted to do the following acetylide alkylation reaction but was unsuccessful in several attempts, producing only the original starting materials in each case. Explain why the reaction didn't work.

Textbook Question

Using the given starting material, any necessary inorganic reagents and catalysts, and any carbon-containing compounds with no more than three carbons, indicate how each of the following compounds can be prepared:

Textbook Question

Suggest a method for synthesizing the following alkynes using an alkyne and an alkyl halide. [There are two correct answers for each product.]

(a)

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