Textbook Question
Show how you would synthesize following tertiary alcohol by adding an appropriate Grignard reagent to a ketone.
c. 1-ethylcyclopentanol
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Ch.10 - Structure and Synthesis of Alcohols
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 10, Problem 17a
Show how you would add Grignard reagent to acid chloride or ester to synthesize the following alcohols.
a. Ph3C–OH
Verified step by step guidance1
Step 1: Identify the target alcohol structure, Ph3C-OH, which is triphenylmethanol. This alcohol has a hydroxyl group attached to a carbon bonded to three phenyl groups.
Step 2: Recognize that Grignard reagents are organomagnesium compounds (R-MgX) that act as nucleophiles. They can attack electrophilic carbonyl groups in acid chlorides or esters to form alcohols.
Step 3: Select the appropriate Grignard reagent for the synthesis. To form Ph3C-OH, use phenylmagnesium bromide (Ph-MgBr) as the Grignard reagent. This reagent will provide the phenyl groups needed for the final alcohol.
Step 4: Choose the starting material. Acid chlorides or esters can be used. For this synthesis, triphenylmethyl chloride (Ph3C-Cl) or an ester derivative of triphenylmethanol can serve as the starting material.
Step 5: Perform the reaction. Add the Grignard reagent (Ph-MgBr) to the acid chloride or ester under anhydrous conditions. The Grignard reagent will attack the carbonyl carbon, forming an intermediate that hydrolyzes upon addition of water or acid to yield the desired alcohol, Ph3C-OH.
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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 add to electrophiles, such as carbonyl compounds, to form new carbon-carbon bonds. In the context of synthesizing alcohols, Grignard reagents react with carbonyl groups in acid chlorides or esters to yield alcohols after hydrolysis.
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02:12
Carbonation of Grignard Reagents
Nucleophilic Addition
Nucleophilic addition is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically found in carbonyl groups. In the case of Grignard reagents, the nucleophile (R-MgX) attacks the carbonyl carbon of an acid chloride or ester, leading to the formation of a tetrahedral intermediate. This step is crucial for the synthesis of alcohols from these carbonyl-containing compounds.
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08:27Nucleophilic Addition
Hydrolysis of the Intermediate
After the nucleophilic addition of a Grignard reagent to an acid chloride or ester, a tetrahedral intermediate is formed. This intermediate can then undergo hydrolysis, typically by adding water or an aqueous acid, to yield the final alcohol product. This step is essential as it converts the magnesium alkoxide intermediate into a stable alcohol, completing the synthesis process.
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04:31Stability of Conjugated Intermediates
Related Practice
Textbook Question
A formate ester, such as ethyl formate, reacts with an excess of a Grignard reagent to give (after protonation) secondary alcohols with two identical alkyl groups.
(a) Propose a mechanism to show how the reaction of ethyl formate with an excess of allylmagnesium bromide gives, after protonation, hepta-1,6-dien-4-ol.
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Textbook Question
Show how you would add Grignard reagent to acid chloride or ester to synthesize the following alcohols.
c. dicyclohexylphenylmethanol
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Textbook Question
Propose a mechanism for the reaction of acetyl chloride with phenylmagnesium bromide to give 1,1-diphenylethanol.
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Textbook Question
Show how you would synthesize following tertiary alcohol by adding an appropriate Grignard reagent to a ketone.
d. 2-cyclopentylpentan-2-ol
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Textbook Question
A formate ester, such as ethyl formate, reacts with an excess of a Grignard reagent to give (after protonation) secondary alcohols with two identical alkyl groups.
(b) Show how you would use reactions of Grignard reagents with ethyl formate to synthesize the following secondary alcohols.
(i) pentan-3-ol
(ii) diphenylmethanol
(iii) trans,trans-nona-2,7-dien-5-ol
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