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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3:05 minutes

Problem 53f

Textbook Question

Predict the products formed when cyclohexanone reacts with the following reagents.
(f) PhMgBr and then mild H₃O⁺

Verified step by step guidance

Step 1: Recognize the type of reaction. Cyclohexanone is a ketone, and PhMgBr is a Grignard reagent. Grignard reagents are nucleophiles that react with carbonyl compounds to form alcohols after hydrolysis.

Step 2: Identify the electrophilic site in cyclohexanone. The carbonyl carbon in cyclohexanone is electrophilic due to the partial positive charge caused by the oxygen atom's electronegativity.

Step 3: Describe the nucleophilic attack. The phenyl group (Ph) from PhMgBr will attack the carbonyl carbon, breaking the π bond of the C=O group and forming a tetrahedral intermediate. This intermediate contains an alkoxide ion (R-O⁻).

Step 4: Explain the role of mild H3O+. The alkoxide ion formed in the previous step is protonated by mild H3O+ (acidic workup), resulting in the formation of a secondary alcohol.

Step 5: Predict the final product. The reaction yields a secondary alcohol where the phenyl group (Ph) is attached to the carbon that was originally part of the carbonyl group in cyclohexanone.

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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, such as PhMgBr, are organomagnesium compounds that act as nucleophiles in organic reactions. They readily react with electrophiles, such as carbonyl compounds, to form alcohols. In this case, PhMgBr will attack the carbonyl carbon of cyclohexanone, leading to the formation of a magnesium alkoxide intermediate.

Nucleophilic Addition

Nucleophilic addition is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophilic center, typically a carbonyl carbon. In the reaction of cyclohexanone with PhMgBr, the nucleophile (PhMgBr) adds to the electrophilic carbon of the carbonyl group, resulting in the formation of a new carbon-carbon bond and an alkoxide intermediate.

Acid Workup

An acid workup, often involving mild H3O+, is a crucial step following nucleophilic addition reactions. It serves to protonate the alkoxide intermediate formed after the Grignard reaction, converting it into a stable alcohol. This step is essential for isolating the final product, which in this case will be a phenyl-substituted alcohol derived from cyclohexanone.

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Related Practice

Textbook Question

Predict the product of the following epoxide opening reactions.

(a)

Textbook Question

Predict the product of the following epoxide opening reactions.

(b)

Textbook Question

A chemist failed to generate the alcohol using the reaction shown here.

(a) Suggest a reason why this reaction did not work as written.

Textbook Question

In lieu of quenching the product of Grignard addition to a carbonyl with acid, alkyl halides can be added directly to generate ether products. Predict the product and show the mechanism of this process.

Textbook Question

Predict the products of the following reactions.

(d) product of (c) + cyclopentylmagnesium bromide, then acidic hydrolysis

Textbook Question

Predict the product of the following reactions.

(a)

Textbook Question

You might expect that aldehydes and ketones could undergo the addition/elimination mechanism. With strong nucleophiles, however, nucleophilic addition is the only outcome. Why?

Textbook Question

Beginning with an amide, two different pathways produce the same compound. Predict the product of these two pathways.

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Predict the products formed when cyclohexanone reacts with the following reagents. (f) PhMgBr and then mild H3O+

Key Concepts

Grignard Reagents

Nucleophilic Addition

Acid Workup

Watch next

Predict the products formed when cyclohexanone reacts with the following reagents.
(f) PhMgBr and then mild H₃O⁺