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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3:40 minutes

Problem 13a

Textbook Question

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

Verified step by step guidance

Step 1: Identify the target molecule. The primary alcohol shown in the first image is benzyl alcohol (C6H5CH2OH), and the second image shows cyclohexylmethanol (C6H11CH2OH). Both are primary alcohols that can be synthesized using a Grignard reagent and formaldehyde.

Step 2: Recall the general reaction mechanism for Grignard reagents with formaldehyde. A Grignard reagent (R-MgX) reacts with formaldehyde (HCHO) to form a primary alcohol after hydrolysis. The R group from the Grignard reagent becomes the alkyl group attached to the hydroxyl group in the alcohol.

Step 3: For benzyl alcohol synthesis, choose the appropriate Grignard reagent. The Grignard reagent should be phenylmagnesium bromide (C6H5MgBr), as the phenyl group (C6H5-) will attach to the formaldehyde carbon during the reaction.

Step 4: For cyclohexylmethanol synthesis, choose the appropriate Grignard reagent. The Grignard reagent should be cyclohexylmagnesium bromide (C6H11MgBr), as the cyclohexyl group (C6H11-) will attach to the formaldehyde carbon during the reaction.

Step 5: Perform the reaction. Add the chosen Grignard reagent to formaldehyde in an ether solvent to form the intermediate alkoxide. Then, hydrolyze the intermediate with water or dilute acid to yield the desired primary alcohol.

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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 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. When Grignard reagents react with carbonyl compounds, such as formaldehyde, they add to the carbonyl carbon, leading to the formation of alcohols after subsequent hydrolysis.

Formaldehyde

Formaldehyde is the simplest aldehyde, with the chemical formula CH2O. It is a reactive carbonyl compound that can undergo nucleophilic addition reactions. When a Grignard reagent reacts with formaldehyde, it forms a primary alcohol after hydrolysis, as the Grignard reagent adds to the carbonyl carbon, resulting in a new carbon-carbon bond and a hydroxyl group.

Synthesis of Alcohols

The synthesis of alcohols from carbonyl compounds is a fundamental reaction in organic chemistry. This process typically involves nucleophilic addition, where a nucleophile (like a Grignard reagent) attacks the electrophilic carbon of the carbonyl group. The resulting alkoxide intermediate can be protonated to yield the corresponding alcohol, which is crucial for building complex organic molecules.

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Related Practice

Textbook Question

Show how you would synthesize the following alcohol by adding Grignard reagents to ethylene oxide.

(a) 2-phenylethanol

Textbook Question

Show how you would add Grignard reagent to acid chloride or ester to synthesize the following alcohols.

a. Ph₃C–OH

Textbook Question

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

b. Ph₃COH

Textbook Question

Show two ways you could synthesize each of the following secondary alcohol by adding an appropriate Grignard reagent to an aldehyde.

(a)

Textbook Question

Show how you would synthesize the following compound from alkyl halides, vinyl halides, and aryl halides containing no more than six carbon atoms.

Textbook Question

Show how you would synthesize the following compound from alkyl halides, vinyl halides, and aryl halides containing no more than six carbon atoms.

(a) octane

Textbook Question

Predict the major products of the following reactions, including stereochemistry where appropriate.

(h) cyclooctylmethanol + CH₃CH₂MgBr

(i) potassium tert-butoxide + methyl iodide

(j) sodium methoxide + tert-butyl iodide

Textbook Question

Which of the following alkyl halides could be successfully used to form a Grignard reagent?

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

Key Concepts

Grignard Reagents

Formaldehyde

Synthesis of Alcohols

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