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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4:29 minutes

Problem 13b

Textbook Question

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

Verified step by step guidance

Step 1: Identify the target molecule, which is a primary alcohol. The structure provided shows a primary alcohol with a branched alkyl chain.

Step 2: Recall the general mechanism for synthesizing a primary alcohol using a Grignard reagent and formaldehyde. Grignard reagents react with formaldehyde to form primary alcohols after hydrolysis.

Step 3: Determine the Grignard reagent needed. The alkyl group attached to the alcohol in the target molecule suggests that the Grignard reagent should be an alkyl magnesium halide with the same alkyl group (e.g., isobutyl magnesium bromide).

Step 4: Write the reaction mechanism. The Grignard reagent (R-MgX) attacks the carbonyl carbon of formaldehyde (HCHO), forming a tetrahedral intermediate. This intermediate is then protonated during the acidic workup to yield the primary alcohol.

Step 5: Summarize the synthesis. Combine formaldehyde with the appropriate Grignard reagent (e.g., isobutyl magnesium bromide) in an ether solvent, followed by an acidic workup to produce 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 represented as R-MgX, where R is an organic group and X is a halogen. They are highly reactive nucleophiles that can react with electrophiles, such as carbonyl compounds, to form new carbon-carbon bonds. In the synthesis of alcohols, Grignard reagents can add to carbonyl groups, leading to the formation of alcohols upon hydrolysis.

Formaldehyde

Formaldehyde (HCHO) is the simplest aldehyde and serves as a key electrophile in organic synthesis. It has a carbonyl group (C=O) that is highly reactive towards nucleophiles, such as Grignard reagents. When a Grignard reagent reacts with formaldehyde, it forms a primary alcohol after subsequent hydrolysis, making it a valuable starting material for synthesizing alcohols.

Synthesis of Primary Alcohols

The synthesis of primary alcohols from aldehydes involves the nucleophilic addition of a Grignard reagent to the carbonyl carbon of the aldehyde. This reaction results in the formation of a magnesium alkoxide intermediate, which can be converted to the corresponding primary alcohol by hydrolysis. This method is significant in organic chemistry for constructing alcohols with specific carbon chain lengths.

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Related Practice

Textbook Question

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

c. dicyclohexylphenylmethanol

Textbook Question

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

(c)

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 following tertiary alcohol by adding an appropriate Grignard reagent to a ketone.

d. 2-cyclopentylpentan-2-ol

Textbook Question

Point out the flaws in the following incorrect Grignard syntheses.

(c)

(d)

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)

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