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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5:22 minutes

Problem 19c

Textbook Question

Predict the product of the following acetylide alkylations.
(c)

Verified step by step guidance

Step 1: Understand the reaction mechanism. Acetylide alkylation involves the reaction of a terminal alkyne with a strong base to form an acetylide ion, followed by the reaction of the acetylide ion with an alkyl halide to form a new carbon-carbon bond.

Step 2: Deprotonate the terminal alkyne. Use a strong base, such as sodium amide (NaNH₂), to remove the acidic proton from the terminal alkyne, forming the acetylide ion. Represent this step as:

R - C \equiv CH + NaNH 2 \to R - C \equiv C - {Na}^{+} + NH 3

Step 3: Identify the alkyl halide. The acetylide ion will act as a nucleophile and attack the electrophilic carbon of the alkyl halide, displacing the halide ion (a substitution reaction). Ensure the alkyl halide is a primary or methyl halide to avoid side reactions like elimination.

Step 4: Perform the nucleophilic substitution. The acetylide ion reacts with the alkyl halide to form a new carbon-carbon bond. Represent this step as:

R - C \equiv C - {Na}^{+} + R' X \to R - C \equiv C R' + NaX

, where R' is the alkyl group and X is the halide.

Step 5: Predict the product. Combine the acetylide ion and the alkyl group from the alkyl halide to form the final product, which is an alkyne with the new carbon-carbon bond. Ensure the structure of the product reflects the substitution reaction accurately.

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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 the deprotonation of terminal alkynes. It is a strong nucleophile, capable of attacking electrophiles in nucleophilic substitution reactions. Understanding the structure and reactivity of acetylide ions is crucial for predicting the outcomes of alkylation reactions.

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile replaces a leaving group in a molecule. This process can occur via two main pathways: SN1 and SN2. The mechanism chosen depends on factors such as the structure of the substrate and the nature of the nucleophile and leaving group.

Alkylation Reaction

Alkylation reactions involve the introduction of an alkyl group into a molecule, often through the reaction of a nucleophile with an alkyl halide. In the context of acetylide alkylation, the acetylide ion acts as the nucleophile, attacking the electrophilic carbon of the alkyl halide, leading to the formation of a new carbon-carbon bond.

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Related Practice

Textbook Question

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

(a)

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

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

(a)

Textbook Question

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

(c)

Textbook Question

A student provided the product of the following reactions, but made a mistake. Identify the mistake, correct the mistake, and suggest a way for the student to avoid that mistake in the future.

(b)

Textbook Question

A student provided the product of the following reactions, but made a mistake. Identify the mistake, correct the mistake, and suggest a way for the student to avoid that mistake in the future.

(a)

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Predict the product of the following acetylide alkylations. (c)

Key Concepts

Acetylide Ion

Nucleophilic Substitution

Alkylation Reaction

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Predict the product of the following acetylide alkylations.
(c)