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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3:15 minutes

Problem 62

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.

Verified step by step guidance

Step 1: Recognize the key reactants and their roles. Estrone is a ketone-containing compound, and sodium acetylide (NaC≡CH) is a strong nucleophile due to the negatively charged acetylide ion. The acetylide ion can attack electrophilic centers, such as the carbonyl group in estrone.

Step 2: Identify the first step of the mechanism. The acetylide ion will perform a nucleophilic attack on the carbonyl carbon of estrone. This occurs because the carbonyl carbon is electrophilic due to the partial positive charge created by the oxygen atom's electronegativity. Represent this step as: Estrone + NaC≡CH → Intermediate (alkoxide).

Step 3: Describe the formation of the intermediate. The nucleophilic attack results in the formation of an alkoxide intermediate, where the oxygen atom from the carbonyl group now carries a negative charge. This intermediate is stabilized by resonance within the molecule.

Step 4: Explain the quenching step. The alkoxide intermediate is quenched with acid (e.g., HCl or H₂SO₄), which protonates the negatively charged oxygen atom, converting it into a hydroxyl group. This step completes the synthesis of the desired product.

Step 5: Highlight the final product. The reaction results in the formation of ethinylestradiol, where the acetylide group has been added to the estrone structure, and the carbonyl group has been converted into a hydroxyl group. This product is a synthetic hormone mimic used in contraceptives.

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Key Concepts

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

Sodium Acetylide as a Nucleophile

Sodium acetylide is a strong nucleophile due to the presence of a negatively charged carbon atom. In organic synthesis, it can attack electrophilic centers, such as carbonyl groups, facilitating the formation of new carbon-carbon bonds. This property is crucial in the synthesis of complex molecules, including hormone mimics like ethinylestradiol.

Carbonyl Chemistry

Carbonyl compounds, such as ketones and aldehydes, are characterized by a carbon-oxygen double bond. They are key intermediates in organic reactions, particularly in nucleophilic addition reactions. Understanding how nucleophiles like sodium acetylide interact with carbonyl groups is essential for proposing a synthesis mechanism involving estrone.

Quenching with Acid

Quenching with acid is a common step in organic synthesis that involves adding an acid to neutralize a reaction mixture, often to protonate reactive intermediates. This step can stabilize the product and facilitate the removal of byproducts. In the context of synthesizing ethinylestradiol, acid quenching would help finalize the reaction and yield the desired hormone mimic.

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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.

a. hex-1-yne

b. hex-2-yne

c. hex-3-yne