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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2:43 minutes

Problem 45a

Textbook Question

Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]
(a)

Verified step by step guidance

Step 1: Understand the concept of acetylide alkylation. Acetylide ions (R-C≡C⁻) are strong nucleophiles that can attack alkyl halides (R-X) in an SN2 reaction, leading to the formation of a new carbon-carbon bond.

Step 2: Identify the acetylide ion and the alkyl halide in the reaction. The acetylide ion is typically generated from a terminal alkyne (R-C≡CH) by deprotonation using a strong base like NaNH₂ or NaH.

Step 3: Write the mechanism of the SN2 reaction. The acetylide ion attacks the carbon atom bonded to the halogen in the alkyl halide, displacing the halide ion (X⁻) and forming a new bond between the acetylide carbon and the alkyl group.

Step 4: Count the number of carbons in the product. Add the number of carbons in the acetylide ion to the number of carbons in the alkyl halide to ensure the product has the correct number of carbons.

Step 5: Draw the structure of the product. Combine the acetylide group (R-C≡C⁻) with the alkyl group from the alkyl halide, ensuring the triple bond remains intact and the connectivity is correct.

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Key Concepts

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

Acetylide Ion

An acetylide ion is a negatively charged species formed by deprotonating a terminal alkyne. It is a strong nucleophile, capable of attacking electrophiles in nucleophilic substitution reactions. Understanding how to generate and utilize acetylide ions is crucial for performing alkylation reactions effectively.

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile replaces a leaving group in a molecule. In the context of acetylide alkylation, the acetylide ion acts as the nucleophile, attacking an alkyl halide to form a new carbon-carbon bond. This process is essential for extending carbon chains in organic synthesis.

Carbon Count in Products

Maintaining the correct number of carbons in the product is vital in organic synthesis, as it ensures the integrity of the molecular structure. In acetylide alkylation, the number of carbons in the starting materials and the alkyl halide must be accounted for to predict the final product accurately. This concept is crucial for verifying the success of the reaction and understanding the resulting compound's properties.

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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

Textbook Question

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

i. sodium amide

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.

a. hex-1-yne

b. hex-2-yne

c. hex-3-yne

Textbook Question

Give two sets of reactants (each set including an alkyl halide and a nucleophile) that could be used to synthesize the following alkyne:

CH₃CH₂C≡CCH₂CH₂CH₂CH₃

Textbook Question

Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]

(c)

Textbook Question

Ethinylestradiol is a synthetic hormone mimic used as a contraceptive for its ability to prevent ovulation. Suggest a mechanism for the synthesis using sodium acetylide and estrone, followed by quenching with acid.

Textbook Question

Predict the product of the following acetylide alkylations.

(a)

Textbook Question

Predict the product of the following acetylide alkylations.

(c)

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