Chapter 15
α-Carbon Chemistry: Enols, Enolates, and Enamines
تفاعل الاينولات
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 ...
تفاعل أيونات الإينولات
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, ...
أنواع الاينولات والإينولات
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 ...
اتفاقيات آلية الإينولات
When a carbonyl compound is treated with a strong base, the α position gets deprotonated to give a resonance-stabilized intermediate called an ...
التكوين الانتقائي للإينولات
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, ...
التأثيرات الكيميائية التجسيمية للإنويل
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 ...
الهالوجين α المحفز بالأحماض من الألدهيدات والكيتونات
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first ...
الهالوجين α المعزز بالقاعدة للألدهيدات والكيتونات
α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. ...
الهالوجين المتعدد لكيتونات الميثيل: تفاعل الهالوجين
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 - الهلوجين لمشتقات حمض الكربوكسيليك: نظرة عامة
Unlike aldehydes and ketones, carboxylic acids do not readily participate in α halogenation reactions via enols or enolate intermediates. However, ...
α برومة أحماض الكربوكسيليك: تفاعل هيل-فولارد-زيلينسكي
The method to achieve α-brominated carboxylic acids using a mixture of phosphorus tribromide and bromine is known as the ...
تفاعلات مركبات α-Halocarbonyl: الاستبدال النووي
Nucleophilic substitution in α-halocarbonyl compounds can be achieved via an SN2 pathway. The reaction in α-haloketones is generally carried out ...
نيتروجين الاينولات
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 ...
تكوين رابطة C-C: نظرة عامة على تكثيف Aldol
Aldol condensation is an important route in synthetic organic chemistry used to generate a new carbon–carbon bond under basic or acidic conditions. ...
تفاعل إضافة Aldol المحفز بالقاعدة
As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy ...
تفاعل إضافة Aldol المحفز بالحمض
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The ...
تجفيف Aldols إلى Enals: تكثيف Aldol المحفز بالقاعدة
This lesson delves into the aldol condensation catalyzed by bases, where aldols undergo dehydration to enals. As shown in Figure 1, the β-hydroxy ...
تجفيف الدولات إلى الإينونات: تكثيف Aldol المحفز بالحمض
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. ...
تفاعل Aldol داخل الجزيئات
Intramolecular aldol reaction occurs in dicarbonyl compounds such as dialdehydes, diketones, and keto-aldehydes. The dicarbonyl compounds possess more ...
انقسام السندات C-C: تفاعل الرجعية Aldol
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 ...
تفاعلات Aldol المتقاطعة: نظرة عامة
Crossed aldol addition is the reaction between two different carbonyl compounds under acidic or basic conditions. Here, both the carbonyl compounds ...
تفاعل Aldol المتقاطع باستخدام قواعد ضعيفة
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 ...
الكيتونات التي تحتوي على ألدهيدات عطرية غير قابلة للاستيلان: تكثيف كلايسن-شميدت
Benzaldehyde, like formaldehyde, lacks an α hydrogen and cannot enolize to form an enolate. Hence, the reaction of benzaldehyde with a ketone in the ...
تفاعل Aldol المتقاطع باستخدام قواعد قوية: تفاعل Aldol الموجه
The reaction between two different carbonyl compounds comprising α hydrogen in the presence of a strong base like lithium diisopropylamide (LDA) to ...
تكثيف Aldol مع β-Diesters: تكثيف Knoevenagel
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as ...
استرات إلى β Ketoesters: نظرة عامة على تكثيف Claisen
Regular Claisen condensation is a base-promoted reaction involving identical esters with two α hydrogens, condensing to produce β-ketoesters. It ...
استرات إلى β-Ketoesters: آلية تكثيف Claisen
Regular Claisen condensation involves the synthesis of β-ketoesters by combining identical ester molecules bearing two α hydrogens in the ...
تكثيف Aldol مقابل تكثيف Claisen
Aldol condensation is an acid or base-catalyzed condensation between aldehydes or ketones to give an α,ꞵ-unsaturated carbonyl compound. A ...
تكثيف Claisen داخل الجزيئات من استرات ثنائي الكربوكسيل: Dieckmann Cycleization
Dieckmann cyclization is an intramolecular Claisen condensation of diesters. The reaction occurs in the presence of a base and generates a cyclic ...
مركبات β-ثنائي الكربونيل عبر تكثيفات الكلايزن المتقاطعة
Crossed Claisen condensations are base-promoted reactions between two different ester molecules producing β-dicarbonyl compounds. The reaction ...
α-ألكلة الكيتونات عن طريق أيونات الإينولات
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by ...
العوامل المؤثرة على α ألكلة الكيتونات: اختيار القاعدة
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 ...
ألكلة β-Ketoester enolates: تخليق أسيتو أسيتيك إستر
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 ...
ألكلة β-Diester enolates: تخليق مالونيك إستر
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
The ...
إضافة مترافقة إلى مركبات الكربونيل غير المشبعة α ، β
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in ...
الجمع المترافق (1،4-الإضافة) مقابل الجمع المباشر (1،2-الإضافة)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic ...
إضافة مترافقة من enolates: إضافة مايكل
The attack of a nucleophile at the β carbon of an α,β-unsaturated carbonyl compound is called conjugate addition. Conjugate addition ...
Cyclohexenones عبر إضافة مايكل وتكثيف Aldol: Anulation Robinson
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, ...
تخليق مركبات الكربونيل المستبدلة α: تفاعل اللقلق إينامين
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines ...
الألدهيدات غير القابلة للشرب إلى الأحماض والكحول: تفاعل كانيزارو
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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