Ch.11 - Reactions of Alcohols

Wade9th EditionOrganic ChemistryISBN: 9780135213728당신이 사용하는 게 아니라요?교과서 변경

Wade 9th Edition

Ch.11 - Reactions of Alcohols

문제 53

11장, 문제 53

Give the structures of the intermediates and products V through Z.

검증된 단계별 안내

Step 1: Analyze the first reaction in the sequence. Cyclopentanol reacts with PBr₃, which is a reagent used to convert alcohols into alkyl bromides. The hydroxyl group (-OH) of cyclopentanol is replaced by a bromine atom, forming cyclopentyl bromide (W).

Step 2: In the second reaction, cyclopentyl bromide (W) reacts with magnesium in ether. This reaction forms a Grignard reagent, cyclopentyl magnesium bromide (X). Grignard reagents are highly reactive organometallic compounds used in nucleophilic addition reactions.

Step 3: Cyclopentanol undergoes oxidation with Na₂Cr₂O₇ in H₂SO₄ to form cyclopentanone (V). This is a typical oxidation reaction where a secondary alcohol is converted into a ketone.

Step 4: The Grignard reagent (X) reacts with cyclopentanone (V) in the presence of H₃O⁺. This reaction forms a tertiary alcohol (Y) through nucleophilic addition of the Grignard reagent to the ketone group of cyclopentanone.

Step 5: The tertiary alcohol (Y) reacts with acetyl chloride (CH₃COCl). This reaction involves acylation, where the hydroxyl group of the alcohol is replaced by an acetyl group, forming an ester (Z).

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Reactions of Alcohols

Alcohols can undergo various reactions, including conversion to alkyl halides. In this case, cyclopentanol is treated with phosphorus tribromide (PBr3), which facilitates the substitution of the hydroxyl group (-OH) with a bromine atom, forming an alkyl bromide. This step is crucial for generating the intermediate W.

Grignard Reagents

Grignard reagents are organomagnesium compounds that react with electrophiles to form new carbon-carbon bonds. In the reaction sequence, the alkyl bromide formed from cyclopentanol reacts with magnesium in ether to produce a Grignard reagent (X). This reagent is highly reactive and can further react with carbonyl compounds in subsequent steps.

Oxidation and Functional Group Transformations

Oxidation reactions involve the increase of oxidation state, often resulting in the formation of carbonyl compounds. In this sequence, the Grignard reagent (X) reacts with a carbonyl compound to form an alcohol (Y), which can then be oxidized using sodium dichromate (Na2Cr2O7) in sulfuric acid (H2SO4) to yield a ketone (Z). Understanding these transformations is essential for predicting the structures of intermediates and products.

관련 실천

교과서 질문

Propose mechanisms for the following reactions. In most cases, more products are formed than are shown here. You only need to explain the formation of the products shown, however.

(b)

679

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교과서 질문

Propose mechanisms for the following reactions. In most cases, more products are formed than are shown here. You only need to explain the formation of the products shown, however.

(a)

934

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교과서 질문

Under acid catalysis, tetrahydrofurfuryl alcohol reacts to give surprisingly good yields of dihydropyran. Propose a mechanism to explain this useful synthesis.

680

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교과서 질문

Predict the major products (including stereochemistry) when cis-3-methylcyclohexanol reacts with the following reagents.

(d) concentrated HBr

(e) TsCl/pyridine, then NaBr

1088

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교과서 질문

Compound A is an optically active alcohol. Treatment with chromic acid converts A into a ketone, B. In a separate reaction, A is treated with PBr₃, converting A into compound C. Compound C is purified, and then it is allowed to react with magnesium in ether to give a Grignard reagent, D. Compound B is added to the resulting solution of the Grignard reagent. After hydrolysis of the initial product (E), this solution is found to contain 3,4-dimethylhexan-3-ol. Propose structures for compounds A, B, C, D, and E.

1798

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교과서 질문

The compound shown below has three different types of OH groups, all with different acidities. Show the structure produced after this compound is treated with different amounts of NaH followed by a methylating reagent. Add a brief explanation.

(a) 1 equivalent of NaH, followed by 1 equivalent of CH₃I and heat

(b) 2 equivalents of NaH, followed by 2 equivalents of CH₃I and heat

1093

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