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

Previous problemNext problem

5:21 minutes

Problem 23c,d

Textbook Question

Point out the flaws in the following incorrect Grignard syntheses.
(c)
(d)

Verified step by step guidance

Step 1: Analyze the reaction in (c). The Grignard reagent, cyclohexylmagnesium bromide (C6H11MgBr), is reacting with acetone (CH3COCH3) under acidic conditions (H3O+). The expected product should involve the addition of the Grignard reagent to the carbonyl group of acetone, forming a tertiary alcohol. However, the product shown is incorrect.

Step 2: Identify the flaw in (c). The product depicted has a tertiary alcohol with an incorrect alkyl group attached to the carbon bearing the hydroxyl group. The Grignard reagent adds the cyclohexyl group to the carbonyl carbon, not the tert-butyl group shown in the product.

Step 3: Analyze the reaction in (d). The starting material is a cyclic ketone with a hydroxyl group (a hydroxy ketone). The Grignard reagent, ethylmagnesium bromide (CH3CH2MgBr), is expected to react with the ketone group, followed by acidic workup (H3O+). The product shown is incorrect.

Step 4: Identify the flaw in (d). The product depicted has two hydroxyl groups, one of which is attached to the carbon that originally had the ketone group. This is not possible because the Grignard reagent reacts with the ketone to form an alcohol, but it cannot introduce a second hydroxyl group at the same carbon.

Step 5: Conclude the analysis. In both cases, the Grignard reagent reacts with the carbonyl group to form an alcohol, but the products shown are inconsistent with the expected mechanism of Grignard reactions. The errors involve incorrect structural representations of the final products.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

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 are highly reactive and used in organic synthesis to form carbon-carbon bonds. They are created by reacting an alkyl or aryl halide with magnesium metal in an anhydrous ether solvent. Understanding their reactivity and the conditions required for their formation is crucial for analyzing any synthetic pathway involving them.

Nucleophilic Addition

Nucleophilic addition is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophilic carbon atom, leading to the formation of a new bond. In the context of Grignard reactions, the Grignard reagent acts as a nucleophile, attacking carbonyl compounds to form alcohols. Recognizing the role of nucleophiles and electrophiles is essential for identifying flaws in synthetic routes.

Reaction Conditions

The reaction conditions, including solvent choice, temperature, and the presence of moisture, are critical in organic reactions, particularly with Grignard reagents, which are sensitive to water. Any moisture can lead to the hydrolysis of Grignard reagents, rendering them ineffective. Understanding the importance of maintaining anhydrous conditions is vital for evaluating the success of Grignard syntheses.

Watch next

Master Reactions of Organometallics with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Show how you would use Grignard syntheses to prepare the following alcohol from the indicated starting material and any other necessary reagents.

(d) 2-cyclohexylethanol from bromocyclohexane

Textbook Question

Show how this 1° alcohol can be made from the following:

(e) an alkene

(f) ethylene oxide

Textbook Question

Show how you would synthesize the following primary alcohol by adding an appropriate Grignard reagent to formaldehyde.

(b)

Textbook Question

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

d. 2-cyclopentylpentan-2-ol

Textbook Question

A variety of organometallics, which as strong nucleophiles can react with epoxides, are introduced in Chapter 16. Predict the product of these reactions. [Hint: Assume the carbon–metal bond in each is ionic, with the carbon possessing the negative charge.]

(b)

Textbook Question

Predict the product of the following epoxide addition reactions.

(b)

Textbook Question

Addition to an epoxide occurs via an S_N2 reaction, but the stereochemistry of the epoxide is retained in the following reaction. Why?

Textbook Question

Show how you would synthesize the following:

f. 2,5-dimethylhexane from a four-carbon alkyl halide

Show more practices