モノかディか? アニリンの潜在制御された電気化学ハロゲン化
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まとめ
この要約は機械生成です。研究者はアニリンの選択的ハロゲン化のための新しい電気化学的方法を開発しました. 精密な電極電位制御により,有機合成を簡素化し,単体または二次置換をターゲットにすることができます.
科学分野
- 有機化学
- 電気化学
- 合成方法論
背景
- 有機反応における置換の度合いを制御するには,しばしば複雑な条件と反応剤が必要で,コストが増加する.
- 選択的有機合成のための直接的かつ効率的な方法の開発は,依然として重要な課題です.
研究 の 目的
- アニリン誘導体の選択的ハロゲン化のための新しい電気化学的戦略を提示する.
- 電極電位を操作することによって反応選択性を正確に制御することを実証する.
主な方法
- 制御された電極電位を持つ電気化学技術を使用して,ハロゲン化反応を駆動します.
- 異なる潜在力での異なる反応性中間物質 (X•とX+) の形成を調査する.
主要な成果
- 選択的*パラ*ハロゲネーションは,低電極電位 (1.38 V 対 SHE) でX−ラジカル中間物質によって達成される.
- 高電極電位 (2.88 V 対 SHE) で X+ 中間物質で達成された二酸化物.
- この方法は,外部酸化物質,移行金属,または塩基を必要としない.
結論
- 電極電位の電気化学的制御は,選択的有機合成のための強力なツールを提供します.
- このアプローチは,アニリン誘導体をハロゲン化するための効率的で代替的な視点を提供します.
- この方法は反応経路を簡素化し,分離コストを削減する可能性があります.
関連する概念動画
α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. The reaction begins with the abstraction of α hydrogen by the base to produce a nucleophilic enolate ion. This intermediate undergoes a subsequent nucleophilic substitution with the halogen to produce a monohalogenated carbonyl compound. If the starting substrate has more than one α hydrogen, it is difficult to stop the reaction...
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
Addition of HCl to an Alkyne
Mechanism I – Vinylic carbocation Intermediate
The mechanism begins with a proton transfer from HCl to the...
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
A...
Chlorination and bromination are important classes of electrophilic aromatic substitutions, where benzene reacts with chlorine or bromine in the presence of a Lewis acid catalyst to give halogenated substitution products. A Lewis acid such as aluminium chloride or ferric chloride catalyzes the chlorination, and ferric bromide catalyzes the bromination reactions. During the bromination of alkenes, bromine polarizes and becomes electrophilic. However, in the bromination of benzene, the bromine...
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Reaction Mechanism
In the first step, a π...
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
Figure 1.
A primary arylamine attacks the nitrosonium ion to form an...

