Ch.11 - Reactions of Alcohols

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

Wade 9th Edition

Ch.11 - Reactions of Alcohols

문제 26a

11장, 문제 26a

Propose a mechanism for each reaction.
(a)

검증된 단계별 안내

Step 1: Recognize the reaction type. This is an acid-catalyzed dehydration reaction where an alcohol is converted into an alkene using concentrated sulfuric acid (H₂SO₄) and heat.

Step 2: Protonation of the alcohol group. The hydroxyl group (-OH) on the cyclopentanol molecule is protonated by H₂SO₄, forming a good leaving group (water). The protonation step increases the electrophilicity of the carbon attached to the hydroxyl group.

Step 3: Formation of the carbocation intermediate. The protonated hydroxyl group leaves as water, generating a carbocation intermediate on the cyclopentane ring. This step is crucial for the subsequent rearrangement or elimination.

Step 4: Elimination of a proton to form the double bond. A base (often HSO₄⁻ or water) abstracts a proton from a β-carbon adjacent to the carbocation, leading to the formation of a double bond (alkene) in the cyclopentane ring.

Step 5: Verify the product. The final product is cyclopentene, an alkene formed by the elimination of water from cyclopentanol. The reaction follows Zaitsev's rule, favoring the most substituted alkene.

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.

Reaction Mechanism

A reaction mechanism is a step-by-step description of how reactants transform into products in a chemical reaction. It outlines the sequence of elementary steps, including bond breaking and forming, and the intermediates involved. Understanding the mechanism helps predict the outcome of reactions and the conditions required for them to occur.

Types of Organic Reactions

Organic reactions can be classified into several types, including substitution, addition, elimination, and rearrangement reactions. Each type has distinct characteristics and mechanisms. Recognizing the type of reaction is crucial for proposing an accurate mechanism, as it influences the pathways and intermediates formed during the reaction.

Curved Arrow Notation

Curved arrow notation is a visual representation used in organic chemistry to illustrate the movement of electrons during a reaction. Arrows indicate the direction of electron flow, showing how bonds are broken and formed. Mastery of this notation is essential for accurately depicting reaction mechanisms and understanding the underlying electron transfer processes.

관련 실천

교과서 질문

Explain why the acid-catalyzed condensation is a poor method for the synthesis of an unsymmetrical ether such as ethyl methyl ether, CH₃CH₂-O-CH₃.

1250

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교과서 질문

Some alcohols undergo rearrangement or other unwanted side reactions when they dehydrate in acid. Alcohols may be dehydrated under mildly basic conditions using phosphorus oxy-chloride (POCl₃) in pyridine. The alcohol reacts with phosphorus oxychloride much like it reacts with tosyl chloride (Section 11-5), displacing a chloride ion from phosphorus to give an alkyl dichlorophosphate ester. The dichlorophosphate group is an outstanding leaving group. Pyridine reacts as a base with the dichlorophosphate ester to give an E2 elimination. Propose a mechanism for the dehydration of cyclohexanol by POCl₃ in pyridine.

2034

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교과서 질문

Contrast the mechanisms of the two preceding reactions, the dehydration and condensation of ethanol.

551

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교과서 질문

Propose a mechanism for each reaction.

(a)

(b)

1106

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교과서 질문

When the following substituted cycloheptanol undergoes dehydration, one of the minor products has undergone a ring contraction. Propose a mechanism to show how this ring contraction occurs.

1032

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교과서 질문

Propose a mechanism for each reaction.

(c)

1203

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Propose a mechanism for each reaction.(a)

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Reaction Mechanism

Types of Organic Reactions

Curved Arrow Notation

Propose a mechanism for each reaction.
(a)