Chapter 15
α-Carbon Chemistry: Enols, Enolates, and Enamines
Enols의 반응성
Enols are a class of compounds where a hydroxyl group is attached to a carbon–carbon double bond, which implies that it is a vinyl alcohol. A ...
Enolate 이온의 반응성
Enolate ions are formed by the acid–base reaction of a carbonyl compound with a base. This leads to deprotonation of the α hydrogen atom, ...
에놀(Enol)과 에놀라산(Enolate)의 종류
Aldehydes and ketones form enols, although only about 1% of the enol is present at the equilibrium for simple monocarbonyl compounds. The enol form is ...
Enolate 메커니즘 규칙
When a carbonyl compound is treated with a strong base, the α position gets deprotonated to give a resonance-stabilized intermediate called an ...
Enolates의 위치 선택적 형성
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, ...
Enolization의 입체화학적 효과
The chiral α-carbon of the carbonyl compound is the stereocenter of the molecule. As shown in the figure below, when such a carbonyl compound ...
알데히드와 케톤의 산 촉매 α-할로겐화
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first ...
알데히드와 케톤의 염기 촉진 α-할로겐화
α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. ...
메틸 케톤의 다중 할로겐화: Haloform 반응
A method involving the transformation of methyl ketones to carboxylic acids using excess base and halogen is called the haloform reaction. It begins with ...
α-Carboxylic Acid Derivatives의 할로겐화: 개요
Unlike aldehydes and ketones, carboxylic acids do not readily participate in α halogenation reactions via enols or enolate intermediates. However, ...
카르복실산의 α-브롬화: 지옥-볼하르트-젤린스키 반응
The method to achieve α-brominated carboxylic acids using a mixture of phosphorus tribromide and bromine is known as the ...
α-할로카르보닐 화합물의 반응: 친핵성 치환
Nucleophilic substitution in α-halocarbonyl compounds can be achieved via an SN2 pathway. The reaction in α-haloketones is generally carried out ...
에놀의 니트로화(nitrosation)
The nitrosation reaction is one of the methods of preparing 1,2-diketones. The enol tautomer of the starting ketone reacts with sodium nitrite in ...
C–C 결합 형성: Aldol 응축 개요
Aldol condensation is an important route in synthetic organic chemistry used to generate a new carbon–carbon bond under basic or acidic conditions. ...
염기 촉매 알돌 첨가 반응
As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy ...
산 촉매 알돌 첨가 반응
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The ...
Aldols에서 Enals로의 탈수: 염기 촉매 알돌 응축
This lesson delves into the aldol condensation catalyzed by bases, where aldols undergo dehydration to enals. As shown in Figure 1, the β-hydroxy ...
Aldols에서 Enones로의 탈수: Acid-Catalyzed Aldol Condensation
As shown in Figure 1, under acidic conditions, the β-hydroxy ketone undergoes dehydration via an E1 elimination reaction to form an enone.
Figure 1. ...
분자내 알돌 반응
Intramolecular aldol reaction occurs in dicarbonyl compounds such as dialdehydes, diketones, and keto-aldehydes. The dicarbonyl compounds possess more ...
C–C 결합 분열: 레트로-알돌 반응
The reverse of the aldol addition reaction is called the retro-aldol reaction. Here, the carbon–carbon bond in the aldol product is cleaved under ...
Crossed Aldol Reactions: 개요
Crossed aldol addition is the reaction between two different carbonyl compounds under acidic or basic conditions. Here, both the carbonyl compounds ...
약한 염기를 사용한 교차 알돌 반응
This lesson deals with the crossed aldol reaction using weak bases. The self-condensation of an aldehyde having α hydrogen is prevented by adding it ...
Nonenolizable 방향족 알데히드를 함유한 케톤: Claisen–Schmidt 응축
Benzaldehyde, like formaldehyde, lacks an α hydrogen and cannot enolize to form an enolate. Hence, the reaction of benzaldehyde with a ketone in the ...
강한 염기를 사용한 교차 알돌 반응: 유도된 알돌 반응
The reaction between two different carbonyl compounds comprising α hydrogen in the presence of a strong base like lithium diisopropylamide (LDA) to ...
β-Diesters를 사용한 Aldol 응축: Knoevenagel 응축
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as ...
에스테르에서 β-케토에스테르로: Claisen 응축 개요
Regular Claisen condensation is a base-promoted reaction involving identical esters with two α hydrogens, condensing to produce β-ketoesters. It ...
에스테르에서 β-케토에스테르로: Claisen 응축 메커니즘
Regular Claisen condensation involves the synthesis of β-ketoesters by combining identical ester molecules bearing two α hydrogens in the ...
Aldol 응축 vs Claisen 응축
Aldol condensation is an acid or base-catalyzed condensation between aldehydes or ketones to give an α,ꞵ-unsaturated carbonyl compound. A ...
Dicarboxylic Esters의 분자 내 Claisen 응축: Dieckmann Cyclization
Dieckmann cyclization is an intramolecular Claisen condensation of diesters. The reaction occurs in the presence of a base and generates a cyclic ...
Crossed Claisen 응축을 통한 β-디카르보닐 화합물
Crossed Claisen condensations are base-promoted reactions between two different ester molecules producing β-dicarbonyl compounds. The reaction ...
Enolate Ions를 통한 케톤의 α-알킬화
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by ...
케톤의 α-알킬화에 영향을 미치는 요인: 염기 선택
α-Alkylation of ketones is achieved in the presence of alkyl halides and a base. The reaction proceeds via the formation of an enolate ion followed ...
β-Ketoester Enolates의 알킬화: Acetoacetic Ester 종합
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide ...
β-Diester Enolates의 알킬화: Malonic 에스테르 합성
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
The ...
α,β-불포화 카르보닐 화합물에 접합체 첨가
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in ...
켤레 덧셈(1,4-덧셈) 대 직접 덧셈(1,2-덧셈)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic ...
Enolates의 켤레 첨가: Michael Addition
The attack of a nucleophile at the β carbon of an α,β-unsaturated carbonyl compound is called conjugate addition. Conjugate addition ...
Michael Addition 및 Aldol Condensation을 통한 Cyclohexenones: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, ...
α 치환된 카르보닐 화합물의 합성: 황새 에나민 반응
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines ...
Nonenolizable Aldehydes에서 산 및 알코올로: Cannizzaro 반응
The Cannizzaro reaction is a base-promoted redox reaction producing a primary alcohol and a carboxylic acid from two molecules of a nonenolizable ...
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