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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4:44 minutes

Problem 31c

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:
c.

Verified step by step guidance

Step 1: Identify the starting material (CH3CH2C≡CH) and the target product (CH3CH2C≡CCH2CH3). The transformation involves adding a CH2CH3 group to the terminal alkyne.

Step 2: Deprotonate the terminal alkyne (CH3CH2C≡CH) using a strong base such as NaNH2 or LDA to generate the acetylide anion (CH3CH2C≡C⁻). This step is crucial for nucleophilic substitution.

Step 3: Select an appropriate alkyl halide for the alkylation reaction. Since the target product requires a CH2CH3 group, use ethyl bromide (CH3CH2Br) or ethyl iodide (CH3CH2I) as the alkylating agent.

Step 4: Perform the alkylation reaction by reacting the acetylide anion (CH3CH2C≡C⁻) with the ethyl halide (CH3CH2Br or CH3CH2I) under SN2 conditions. This will result in the formation of CH3CH2C≡CCH2CH3.

Step 5: Verify the product structure to ensure the addition of the CH2CH3 group to the terminal alkyne, completing the synthesis of CH3CH2C≡CCH2CH3.

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Key Concepts

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

Alkyne Reactions

Alkynes are hydrocarbons containing at least one carbon-carbon triple bond. They can undergo various reactions, including addition reactions where reagents add across the triple bond. Understanding how to manipulate these reactions is crucial for synthesizing more complex molecules, such as converting 1-butyne (CH3CH2C≡CH) to 1-pentyne (CH3CH2C≡CCH2CH3) through appropriate reagents.

Carbon Chain Extension

Carbon chain extension involves adding carbon atoms to a molecule to increase its length. This can be achieved through reactions such as alkylation, where an alkyl group is transferred to a nucleophile. In the context of the question, extending the carbon chain from butyne to pentyne requires a suitable alkylating agent and conditions that favor the formation of the desired product.

Reagents and Catalysts

In organic synthesis, reagents and catalysts play a vital role in facilitating chemical reactions. Reagents are substances that participate in the reaction, while catalysts speed up the reaction without being consumed. Identifying the correct reagents and catalysts is essential for successfully converting starting materials into target compounds, as seen in the transformation of CH3CH2C≡CH to CH3CH2C≡CCH2CH3.

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Related Practice

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

Show how the following compounds can be prepared, using ethyne as one of the starting materials:

3. 2-methyl-3-hexyn-2-ol

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

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

(a)

Textbook Question

Show how you would accomplish the following synthetic transformations. Show all intermediates.

c. but-1-yne → oct-3-yne

Multiple Choice

Predict the major, organic product of the following reaction.

Textbook Question

What is the major product of the reaction of 1 mol of propyne with each of the following reagents?

j. the product of part i followed by 1-chloropropane

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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:c.

Key Concepts

Alkyne Reactions

Carbon Chain Extension

Reagents and Catalysts

Watch next

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:
c.