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

14. Synthetic Techniques

Retrosynthesis

Organic Chemistry

14. Synthetic Techniques

Retrosynthesis

Previous problemNext problem

3:45 minutes

Problem 39e

Textbook Question

Show how you would use Grignard syntheses to prepare the following alcohol from the indicated starting material and any other necessary reagents.
(e) benzyl alcohol (Ph–CH₂–OH) from bromobenzene (Ph–Br)

Verified step by step guidance

Step 1: Begin by preparing the Grignard reagent from the starting material, bromobenzene (Ph-Br). React bromobenzene with magnesium (Mg) in an anhydrous ether solvent (e.g., diethyl ether) to form phenylmagnesium bromide (Ph-MgBr). This reaction is represented as: Ph-Br + Mg → Ph-MgBr.

Step 2: To introduce the -CH2OH group, react the Grignard reagent (Ph-MgBr) with formaldehyde (HCHO). Formaldehyde is the simplest aldehyde and will add a single carbon to the benzene ring. The reaction proceeds via nucleophilic addition, where the carbon in Ph-MgBr attacks the carbonyl carbon of formaldehyde.

Step 3: After the nucleophilic addition, the intermediate formed is a magnesium alkoxide. This intermediate has the structure Ph-CH2-O-MgBr.

Step 4: Perform an acidic workup by adding a dilute acid (e.g., HCl or H2SO4) to the reaction mixture. This step protonates the alkoxide group (-O-MgBr) to form the desired alcohol, benzyl alcohol (Ph-CH2-OH).

Step 5: Verify the product structure and ensure that the reaction conditions are anhydrous during the Grignard reagent preparation, as Grignard reagents are highly reactive with water and will decompose if exposed to moisture.

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, typically represented as R-MgX, where R is an organic group and X is a halogen. They are highly reactive and can act as nucleophiles, allowing them to react with electrophiles to form new carbon-carbon bonds. In the context of synthesizing alcohols, Grignard reagents can react with carbonyl compounds to yield alcohols after hydrolysis.

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the case of Grignard synthesis, the nucleophilic Grignard reagent attacks the electrophilic carbon in a carbon halide, leading to the formation of a new carbon-carbon bond. This mechanism is crucial for constructing complex organic molecules.

Hydrolysis of Grignard Reagents

Hydrolysis of Grignard reagents is the process where the Grignard reagent reacts with water or an alcohol to form the corresponding alcohol and magnesium hydroxide halide. This step is essential after the nucleophilic attack, as it converts the intermediate alkoxide formed during the reaction into a stable alcohol. Understanding this step is vital for completing the synthesis of the desired alcohol product.

Watch next

Master Intro with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Show how you would synthesize the following compounds. As starting materials, you may use any alcohols containing four or fewer carbon atoms, cyclohexanol, and any necessary solvents and inorganic reagents.

(a)

(b)

(c)

Textbook Question

Determine the structures of compounds A through G, including stereochemistry where appropriate.

Textbook Question

Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.

(c)

Textbook Question

Starting from bromobenzene and any other reagents and solvents you need, show how you would synthesize the following compounds. Any of these products may be used as starting materials in subsequent parts of this problem.

d. 3-phenylprop-2-en-1-ol

Textbook Question

Using cyclohexanone as the starting material, describe how each of the following compounds can be synthesized:

Textbook Question

How could the following compounds be prepared, using cyclohexene as a starting material?

Textbook Question

Using the given starting material, any necessary inorganic reagents and catalysts, and any carbon-containing compounds with no more than three carbons, indicate how each of the following compounds can be prepared:

Textbook Question

Which of the reactions cannot be used for the synthesis of isobutyl alcohol?

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

Show how you would use Grignard syntheses to prepare the following alcohol from the indicated starting material and any other necessary reagents.(e) benzyl alcohol (Ph–CH2–OH) from bromobenzene (Ph–Br)

Key Concepts

Grignard Reagents

Nucleophilic Substitution

Hydrolysis of Grignard Reagents

Watch next

Show how you would use Grignard syntheses to prepare the following alcohol from the indicated starting material and any other necessary reagents.
(e) benzyl alcohol (Ph–CH₂–OH) from bromobenzene (Ph–Br)