Ch. 14 - Ethers, Epoxides, and Thioethers

Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook

Wade 9th Edition

Ch. 14 - Ethers, Epoxides, and Thioethers

Problem 33m,n

Chapter 14, Problem 33m,n

Predict the products of the following reactions.
(m)
(n)

Verified step by step guidance

Step 1: Analyze the structure of the starting material in reaction (m). The molecule is a cyclic ketone (cyclohexanone derivative) with a methyl group attached to the alpha-carbon.

Step 2: Identify the reagents in reaction (m). CH3O⁻ (methoxide ion) and CH3OH (methanol) indicate that the reaction is under basic conditions, likely leading to nucleophilic attack by the methoxide ion.

Step 3: Predict the mechanism for reaction (m). Under basic conditions, the methoxide ion will attack the carbonyl carbon of the ketone, forming a tetrahedral intermediate. This intermediate will collapse, leading to the formation of an acetal or hemiacetal product.

Step 4: Analyze the structure of the starting material in reaction (n). The molecule is the same cyclic ketone as in (m). However, the reagents are CH3OH (methanol) and H⁺ (acidic conditions).

Step 5: Predict the mechanism for reaction (n). Under acidic conditions, the carbonyl oxygen will be protonated, increasing the electrophilicity of the carbonyl carbon. Methanol will then attack the carbonyl carbon, forming a tetrahedral intermediate. Subsequent steps will lead to the formation of an acetal product.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nucleophilic Attack

Nucleophilic attack is a fundamental reaction mechanism in organic chemistry where a nucleophile, which is an electron-rich species, attacks an electron-deficient center, typically a carbon atom in a carbonyl group. In the context of the provided reaction, the nucleophiles CH3O− and CH3OH can attack the carbonyl carbon of the cyclic compound, leading to the formation of new bonds and the potential opening of the ring structure.

Carbonyl Compounds

Carbonyl compounds, characterized by the presence of a carbon-oxygen double bond (C=O), are key functional groups in organic chemistry. They include aldehydes, ketones, and carboxylic acids, and they are highly reactive due to the polarization of the C=O bond. In the given reaction, the carbonyl group in the cyclic compound is crucial for determining the products formed after nucleophilic attack.

Reaction Mechanism

A reaction mechanism describes the step-by-step process by which reactants are converted into products, detailing the bond-breaking and bond-forming events. Understanding the mechanism is essential for predicting the products of a reaction, as it provides insight into the intermediates formed and the overall pathway taken. In this case, analyzing how CH3O− and CH3OH interact with the carbonyl compound will help predict the final products.

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Related Practice

Textbook Question

Show how you would make the following ethers, using only simple alcohols and any needed reagents as your starting materials.

(a) 1-methoxybutane

(b) 2-ethoxy-2-methylpropane

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Textbook Question

Predict the products of the following reactions.

(j)

(k)

(l)

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Textbook Question

(A true story.) An inexperienced graduate student moved into a laboratory and began work. He needed some diethyl ether for a reaction, so he opened an old, rusty 1-gallon can marked 'ethyl ether' and found there was half a gallon left. To purify the ether, the student set up a distillation apparatus, started a careful distillation, and went to the stockroom for the other reagents he needed. While he was at the stockroom, the student heard a muffled "boom." He quickly returned to his lab to find a worker from another laboratory putting out a fire. Most of the distillation apparatus was embedded in the ceiling.

(a) Explain what probably happened.

(b) Explain how this near-disaster might have been prevented.

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Textbook Question

Predict the products of the following reactions.

(a) sec-butyl isopropyl ether + concd. HBr, heat

(b) 2-ethoxy-2-methylpentane + concd. HBr, heat

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Textbook Question

(a) Show how you would synthesize the pure (R) enantiomer of 2-butyl methyl sulfide, starting with pure (R)-butan-2-ol and any reagents you need

(b) Show how you would synthesize the pure (S) enantiomer of the product, still starting with (R)-butan-2-ol and any reagents you need.

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