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

Organometallic Cumulative Practice

Organic Chemistry

13. Alcohols and Carbonyl Compounds

Organometallic Cumulative Practice

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3:55 minutes

Problem 28a

Textbook Question

Show how you would add a Grignard reagent to an ester or a nitrile to synthesize
(a) 4-phenylheptan-4-ol.

Verified step by step guidance

Step 1: Understand the target molecule. The target molecule, 4-phenylheptan-4-ol, is a tertiary alcohol with a phenyl group attached to the fourth carbon. This suggests that a Grignard reagent will react with a carbonyl compound to form the alcohol.

Step 2: Choose the starting material. To synthesize a tertiary alcohol, a Grignard reagent must react with either an ester or a nitrile. In this case, an ester is a suitable choice because it allows for the addition of two alkyl groups from the Grignard reagent.

Step 3: Select the Grignard reagent. The Grignard reagent should provide the phenyl group (C₆H₅) and the appropriate alkyl chain to form the desired product. Use phenylmagnesium bromide (C₆H₅MgBr) as the Grignard reagent.

Step 4: React the ester with the Grignard reagent. The ester (e.g., ethyl butanoate, CH₃CH₂CH₂COOCH₂CH₃) will undergo nucleophilic attack by the Grignard reagent. The first equivalent of the Grignard reagent will form a ketone intermediate, and the second equivalent will react with the ketone to form the tertiary alcohol.

Step 5: Perform the workup. After the reaction is complete, add water or dilute acid to protonate the alkoxide intermediate and isolate the final product, 4-phenylheptan-4-ol.

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Key Concepts

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

Grignard Reagents

Grignard reagents are organomagnesium compounds that act as nucleophiles in organic reactions. They are formed by reacting alkyl or aryl halides with magnesium metal in dry ether. These reagents can react with carbonyl compounds, such as esters and nitriles, to form alcohols after hydrolysis. Understanding their reactivity is crucial for synthesizing complex organic molecules.

Ester Reactivity

Esters are functional groups characterized by a carbonyl (C=O) adjacent to an ether (C-O) group. They can undergo nucleophilic addition reactions, where a Grignard reagent attacks the carbonyl carbon, leading to the formation of a tetrahedral intermediate. This intermediate can then be protonated to yield an alcohol. Recognizing how esters react with Grignard reagents is essential for the synthesis of alcohols like 4-phenylheptan-4-ol.

Nitrile Reactivity

Nitriles contain a carbon triple-bonded to a nitrogen atom and can also react with Grignard reagents. The nucleophilic attack by the Grignard reagent on the carbon of the nitrile leads to the formation of an intermediate that can be hydrolyzed to yield an amine or an alcohol. This reactivity is important for constructing carbon skeletons in organic synthesis, particularly when aiming for specific alcohols.