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

13. Alcohols and Carbonyl Compounds

Grignard Reaction

Organic Chemistry

13. Alcohols and Carbonyl Compounds

Grignard Reaction

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5:10 minutes

Problem 20a,b

Textbook Question

Acetylide ions also add to ethylene oxide much like Grignard and organolithium reagents. Predict the products obtained by adding the following acetylide ions to ethylene oxide, followed by a dilute acid workup.
(a) HC≡C:^–
(b) CH₃CH₂–C≡C:^–

Verified step by step guidance

Step 1: Understand the reaction mechanism. Acetylide ions are strong nucleophiles that attack the electrophilic carbon in ethylene oxide, opening the three-membered ring. This results in the formation of an alkoxide intermediate.

Step 2: Analyze the acetylide ions provided. In part (a), the acetylide ion is HC≡C⁻, and in part (b), the acetylide ion is CH₃CH₂C≡C⁻. These ions will act as nucleophiles in the reaction.

Step 3: Predict the intermediate formed after the nucleophilic attack. The acetylide ion attacks the less sterically hindered carbon of ethylene oxide, breaking the ring and forming a linear alkoxide intermediate. For part (a), the intermediate will have a terminal alkyne group, and for part (b), the intermediate will have a substituted alkyne group.

Step 4: Perform the acid workup. The alkoxide intermediate is protonated by dilute acid, converting it into an alcohol. The alcohol will be located on the carbon adjacent to the alkyne group.

Step 5: Write the general product structure. For part (a), the product will be HC≡C-CH₂CH₂OH. For part (b), the product will be CH₃CH₂C≡C-CH₂CH₂OH. These products are formed after the acid workup step.

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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, capable of attacking electrophilic centers, such as carbon atoms in epoxides. In this context, acetylide ions react with ethylene oxide to open the epoxide ring, leading to the formation of alcohols after subsequent acid workup.

Ethylene Oxide Reactivity

Ethylene oxide is a three-membered cyclic ether that is highly reactive due to its strained ring structure. It can undergo nucleophilic attack at the less hindered carbon atom, leading to ring opening. This property makes it a suitable substrate for reactions with nucleophiles like acetylide ions, resulting in the formation of alcohols after hydrolysis.

Dilute Acid Workup

A dilute acid workup is a common procedure in organic synthesis used to protonate and stabilize reaction products. After the nucleophilic addition of acetylide ions to ethylene oxide, the dilute acid helps to convert the alkoxide intermediate into the corresponding alcohol. This step is crucial for ensuring that the final product is in its stable, protonated form.

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Related Practice

Textbook Question

Show how to make these deuterium-labeled compounds, using CD₃MgBr and D₂O as your sources of deuterium, and any non-deuterated starting materials you wish.

d. Ph(CD₃)₂COD

Textbook Question

Show how to make these deuterium-labeled compounds, using CD₃MgBr and D₂O as your sources of deuterium, and any non-deuterated starting materials you wish.

b. CH₃C(OH)(CD₃)₂

Textbook Question

Show how to make these deuterium-labeled compounds, using CD₃MgBr and D₂O as your sources of deuterium, and any non-deuterated starting materials you wish.

a. CH₃CH(OD)CD₃

Textbook Question

Show how you would synthesize the following:

a. 2-phenylethanol by the addition of formaldehyde to a suitable Grignard reagent

Textbook Question

Show how you would synthesize the following alcohol by adding Grignard reagents to ethylene oxide.

(a) 2-phenylethanol

Textbook Question

Show how you would add Grignard reagent to acid chloride or ester to synthesize the following alcohols.

a. Ph₃C–OH

Textbook Question

Show how you would synthesize following tertiary alcohol by adding an appropriate Grignard reagent to a ketone.

b. Ph₃COH

Textbook Question

Show two ways you could synthesize each of the following secondary alcohol by adding an appropriate Grignard reagent to an aldehyde.

(a)

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Acetylide ions also add to ethylene oxide much like Grignard and organolithium reagents. Predict the products obtained by adding the following acetylide ions to ethylene oxide, followed by a dilute acid workup. (a) HC≡C:–(b) CH3CH2–C≡C:–

Key Concepts

Acetylide Ions

Ethylene Oxide Reactivity

Dilute Acid Workup

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Acetylide ions also add to ethylene oxide much like Grignard and organolithium reagents. Predict the products obtained by adding the following acetylide ions to ethylene oxide, followed by a dilute acid workup.
(a) HC≡C:^–
(b) CH₃CH₂–C≡C:^–