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Ch.11 - Reactions of Alcohols
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Wade 9th EditionCh.11 - Reactions of Alcohols문제 39h,i,j
11장, 문제 39h,i,j

Predict the major products of the following reactions, including stereochemistry where appropriate.
(h) cyclooctylmethanol + CH3CH2MgBr
(i) potassium tert-butoxide + methyl iodide
(j) sodium methoxide + tert-butyl iodide

검증된 단계별 안내
1
Step 1: For reaction (h), cyclooctylmethanol reacts with CH3CH2MgBr, a Grignard reagent. Grignard reagents are strong nucleophiles and bases. The hydroxyl group (-OH) in cyclooctylmethanol will react with the Grignard reagent, leading to the formation of a cyclooctylmethoxide intermediate and ethane gas (CH3CH3). This reaction does not proceed further to form a carbon-carbon bond because the alcohol group is acidic and reacts with the Grignard reagent.
Step 2: For reaction (i), potassium tert-butoxide (KOtBu) reacts with methyl iodide (CH3I). This is an example of an SN2 reaction, where the nucleophile (tert-butoxide ion) attacks the electrophilic carbon in methyl iodide, displacing the iodide ion. The product formed is tert-butyl methyl ether (CH3-O-C(CH3)3). The reaction proceeds with inversion of configuration at the electrophilic carbon, but since methyl iodide is achiral, stereochemistry is not relevant here.
Step 3: For reaction (j), sodium methoxide (CH3ONa) reacts with tert-butyl iodide (C(CH3)3I). Due to the steric hindrance around the tert-butyl group, an SN2 reaction is unlikely. Instead, this reaction proceeds via an E2 elimination mechanism. Sodium methoxide acts as a strong base, abstracting a proton from one of the methyl groups adjacent to the carbon bonded to iodine. This leads to the formation of isobutene (CH2=C(CH3)2) and sodium iodide (NaI).
Step 4: In reaction (h), the Grignard reagent acts as a base rather than a nucleophile due to the presence of the hydroxyl group. This is a key concept to understand when predicting the outcome of reactions involving alcohols and Grignard reagents.
Step 5: In reactions (i) and (j), the steric hindrance and the nature of the nucleophile/base determine whether the reaction proceeds via SN2 or E2 mechanisms. Understanding these factors is crucial for predicting the major product and stereochemistry of such reactions.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
7m

주요 개념

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

Grignard Reagents

Grignard reagents, such as CH3CH2MgBr, are organomagnesium compounds that act as nucleophiles in organic reactions. They can react with electrophiles, including carbonyl compounds, to form alcohols. In the context of the first reaction, cyclooctylmethanol will react with the Grignard reagent to form a new carbon-carbon bond, leading to the formation of a more complex alcohol.
추천 영상:
02:12
Carbonation of Grignard Reagents

Elimination Reactions

Elimination reactions involve the removal of a small molecule from a larger one, often resulting in the formation of a double bond. In the second reaction, potassium tert-butoxide acts as a strong base, promoting the elimination of iodide from methyl iodide to form an alkene. Understanding the mechanism of elimination is crucial for predicting the products and their stereochemistry.
추천 영상:
00:40
Recognizing Elimination Reactions.

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile replaces a leaving group in a molecule. In the third reaction, sodium methoxide acts as a nucleophile, attacking the tert-butyl iodide to displace the iodide ion. The mechanism (either SN1 or SN2) will influence the stereochemistry of the product, making it essential to consider when predicting the outcome.
추천 영상:
01:47
Nucleophiles and Electrophiles can react in Substitution Reactions.
관련 실천
교과서 질문

Predict the major products of the following reactions, including stereochemistry where appropriate.

(n) sodium ethoxide + 2-methyl-2-bromobutane

(o) octan-1-ol + DMSO + oxalyl chloride

(p) 4-cyclopentylhexan-1-ol + DMP reagent

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교과서 질문

Predict the major products of the following reactions, including stereochemistry where appropriate.

(e) cyclopentylmethanol + Na2Cr2O7/H2SO4

(f) cyclopentanol + HCl/ZnCl2

(g) n-butanol + HBr

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교과서 질문

Predict the major products of the following reactions, including stereochemistry where appropriate.

(k) cyclopentanol + H2SO4/heat

(l) product from (k) + OsO4/H2O2, then HIO4

(m) sodium ethoxide + 1-bromobutane

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교과서 질문

Show how you would convert 2-methylcyclopentanol to the following products. Any of these products may be used as the reactant in any subsequent part of this problem.

a. 1-methylcyclopentene

b. 2-methylcyclopentyl tosylate

c. 2-methylcyclopentanone

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교과서 질문

Predict the major products of the following reactions, including stereochemistry where appropriate.

(c) cyclooctanol + NaOCl/HOAC

(d) cyclopentylmethanol + CrO3·pyridine·HCl

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교과서 질문

Predict the major products of the following reactions, including stereochemistry where appropriate.

(a) (R)-butan-2-ol + TsCl in pyridine

(b) (S)-2-butyl tosylate + NaBr

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