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

22. Carboxylic Acid Derivatives: NAS

Nucleophilic Acyl Substitution

Organic Chemistry

22. Carboxylic Acid Derivatives: NAS

Nucleophilic Acyl Substitution

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2:27 minutes

Problem 50h

Textbook Question

Predict the products of the following reactions:.
(h)

Verified step by step guidance

Step 1: Identify the functional groups in the starting material. The molecule contains a cyclic ester (lactone) functional group, which is reactive towards nucleophiles like Grignard reagents.

Step 2: Recognize the reagent used. PhMgBr is a phenyl Grignard reagent, which acts as a nucleophile and attacks electrophilic carbon atoms, such as the carbonyl carbon in the ester group.

Step 3: Predict the first reaction step. The Grignard reagent will attack the carbonyl carbon of the ester, breaking the C=O bond and forming a tetrahedral intermediate. Since excess PhMgBr is used, the intermediate will react further, leading to the cleavage of the ester bond and formation of a secondary alcohol.

Step 4: Consider the second reaction step. After the Grignard reagent reacts, the addition of H3O+ (acidic workup) will protonate the oxygen atoms, stabilizing the product and completing the reaction.

Step 5: Predict the final product. The reaction will yield a tertiary alcohol where two phenyl groups (Ph) are attached to the carbon that was originally part of the carbonyl group in the ester. The cyclic structure will open due to the cleavage of the ester bond.

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Key Concepts

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

Nucleophilic Addition Reactions

Nucleophilic addition reactions involve the attack of a nucleophile on an electrophilic carbon atom, typically found in carbonyl groups. In this case, the phenylmagnesium bromide (PhMgBr) acts as a nucleophile, attacking the carbonyl carbon of the cyclic compound. This reaction leads to the formation of an alkoxide intermediate, which can be protonated in a subsequent step to yield an alcohol.

Grignard Reagents

Grignard reagents, such as phenylmagnesium bromide (PhMgBr), are organomagnesium compounds that are highly reactive nucleophiles. They are used to form carbon-carbon bonds by attacking electrophilic centers, such as carbonyls. The excess of Grignard reagent in this reaction indicates that it will react with both carbonyl groups in the cyclic compound, leading to the formation of a tertiary alcohol after protonation.

Protonation of Alkoxides

After the nucleophilic addition of a Grignard reagent to a carbonyl compound, the resulting alkoxide intermediate must be protonated to form the final alcohol product. This is typically achieved by adding a proton source, such as dilute acid (H3O+), which donates a proton to the negatively charged oxygen of the alkoxide. This step is crucial for converting the intermediate into a stable alcohol, completing the reaction.

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