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

Previous problemNext problem

1:14 minutes

Problem 19a

Textbook Question

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

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. The reaction can be represented as:

R - C \equiv CH + {Na}_{NH} \to R - C \equiv C - {Na}_{+} + {NH}_{3}

Step 3: Identify the alkyl halide. The acetylide ion will react with an alkyl halide (e.g., R'-X, where X is a leaving group such as Br or I) in an SN2 reaction. This step forms a new carbon-carbon bond.

Step 4: Perform the SN2 reaction. The acetylide ion acts as a nucleophile and attacks the electrophilic carbon of the alkyl halide, displacing the leaving group. The reaction can be represented as:

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

Step 5: Predict the product. Combine the alkyne fragment (R-C≡C-) with the alkyl group (R') from the alkyl halide to form the final product, which is a substituted alkyne (R-C≡C-R'). Ensure that the alkyl halide used is primary or methyl to avoid side reactions such as elimination.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Acetylide Ions

Acetylide ions are negatively charged species formed from terminal alkynes by deprotonation. They are strong nucleophiles due to the high electron density on the carbon atom. Understanding their formation and reactivity is crucial for predicting the outcomes of reactions involving alkylation, where they attack electrophiles to form new carbon-carbon bonds.

Alkylation Reactions

Alkylation reactions involve the transfer of an alkyl group from one molecule to another, typically through nucleophilic substitution. In the context of acetylide alkylation, the acetylide ion acts as a nucleophile, attacking an alkyl halide or other electrophile to form a new alkyne. Recognizing the mechanism and conditions of these reactions is essential for predicting the final product.

Electrophiles

Electrophiles are species that accept electrons during a chemical reaction, often possessing a positive charge or a partial positive charge. In alkylation reactions, common electrophiles include alkyl halides, which react with nucleophiles like acetylide ions. Understanding the nature of electrophiles helps in predicting which products will form based on the reactivity and sterics of the electrophile involved.

Watch next

Master Understanding how to convert terminal alkynes to alkynides. with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

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.]

(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.

(c)

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)

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

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

Key Concepts

Acetylide Ions

Alkylation Reactions

Electrophiles

Watch next

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