Textbook Question
Show how you would synthesize the following alcohol by adding Grignard reagents to ethylene oxide.
(c)
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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 19a
Show how you would synthesize the following alcohol by adding Grignard reagents to ethylene oxide.
(a) 2-phenylethanol
Verified step by step guidance1
Step 1: Understand the reaction mechanism. Grignard reagents are organomagnesium compounds (R-MgX) that act as nucleophiles. They attack electrophilic centers, such as the carbon in ethylene oxide, to form new carbon-carbon bonds.
Step 2: Identify the Grignard reagent needed. To synthesize 2-phenylethanol, the Grignard reagent should contain a phenyl group (C₆H₅). Therefore, the Grignard reagent to use is phenylmagnesium bromide (C₆H₅-MgBr).
Step 3: React the Grignard reagent with ethylene oxide. The phenylmagnesium bromide will attack the electrophilic carbon in ethylene oxide, opening the epoxide ring and forming a new bond between the phenyl group and one of the carbons in the ethylene oxide.
Step 4: Perform hydrolysis. After the Grignard reagent reacts with ethylene oxide, the intermediate product is treated with water or dilute acid to protonate the oxygen atom, resulting in the formation of 2-phenylethanol.
Step 5: Verify the product structure. The final product should have a phenyl group attached to a two-carbon chain ending in an alcohol group (-OH), which matches the structure of 2-phenylethanol.
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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 and serve as nucleophiles in organic synthesis, allowing for the formation of carbon-carbon bonds. When reacted with electrophiles, such as carbonyl compounds or epoxides, they can lead to the formation of alcohols, making them essential in synthetic organic chemistry.
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Carbonation of Grignard Reagents
Ethylene Oxide
Ethylene oxide is a three-membered cyclic ether that is highly reactive due to its strained ring structure. It can undergo nucleophilic attack, making it a useful substrate for Grignard reagents. When a Grignard reagent attacks ethylene oxide, it opens the epoxide ring, leading to the formation of an alcohol after subsequent protonation, which is crucial for synthesizing specific alcohols like 2-phenylethanol.
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Synthesis of Alcohols
The synthesis of alcohols often involves the addition of nucleophiles to electrophiles. In this case, the nucleophilic Grignard reagent adds to the electrophilic carbon of the ethylene oxide, resulting in the formation of a new carbon-carbon bond. This process is fundamental in organic chemistry, as it allows for the construction of complex molecules and the introduction of functional groups, such as hydroxyl groups in alcohols.
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Related Practice
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
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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.
(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
Acetylide ions also add to ethylene oxide much like Grignard and organolithium reagents. Predict the products obtained by adding the following acetylide ions to ethylene oxide, followed by a dilute acid workup.
(a) HC≡C:–
(b) CH3CH2–C≡C:–
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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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