関連する実験動画
Updated: Apr 11, 2026

10:44
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
11.9K
循環性 (アルキル) (アミノ) カーベンから派生した空気中持久性モノメリック (アミノ) (アミノ) カーボキシラジカル
Janell K Mahoney1, David Martin1,2, Fabrice Thomas2
1†UCSD-CNRS Joint Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0343, United States.
Journal of the American Chemical Society
|May 27, 2015
まとめ
電子を取り除くカルボニル基を持つ新しい (アミノ) カーボキシラジカルは,溶液で数日間持続する安定性が向上しています. 電子性質が変化し,酸素との反応性に影響する.
科学分野:
- 有機化学 オーガニック・ケミストリー
- ラジカル・ケミストリー (Radical Chemistry) とは
- コンピューティング・ケミストリー
背景:
- モノメア (アミノ) ・カーボキシ) 基は,以前は空気に対して非常に敏感であると考えられていた.
- サイクル (アルキ) ・アミノ) カーベン (CAACs) は,激素合成の安定した前駆体である.
研究 の 目的:
- 新しい (アミノ) ・カーボキシ) ラジカルを電子を取り除くカルボニル置換剤によって合成する.
- これらのラジカルの安定性と電子特性を調査する.
- 代替剤が,特に二酸化炭素に対して,急性反応性に対する影響を調査する.
主な方法:
- 安定したサイクリック (アルキ) (アミノ) カーベン (CAAC) からモノメア (アミノ) カーボキシラジカルを二,三段階で合成する.
- 空気溶液で合成されたラジカルの安定性評価.
- 電子構造と反応エネルギー分析のための密度関数理論 (DFT) 計算.
主要な成果:
- 電子を取り除くカーボニル置換剤を増やした (アミノ) ・ (カーボキシ) ラジカル (3a-3e) の一連の合成に成功しました.
- 空気溶液中の半減期が時間 (3d) と日 (3c,3e) で,以前の仮定に反して,安定性の向上が観察されました.
- DFTの計算により,Cを中心とするC,O-ラジカルからC,O-ラジカルへの移行が明らかになった.
- 電子欠乏性の高い急性分子に対する二酸化炭素添加時に過酸化物形成のための予測された不安定化および内熱反応.
結論:
- 電子を取り除くカルボニル置換剤は, (アミノ) ・ (カルボキシ) 基の安定性を著しく高めます.
- 置換物の電子的性質は,原素の性質と酸素に対する反応性を決定する.
- これらの発見は,合成化学でより安定した基質種を活用するための道を開きます.
関連する概念動画
Radical Reactivity: Electrophilic Radicals
2.6K
Radicals adjacent to electron‐withdrawing groups are called electrophilic radicals. These radicals readily react with nucleophilic alkenes. For example, the malonate radical, in which the radical center is flanked by two electron‐withdrawing groups, reacts readily with butyl vinyl ether, which consists of an electron‐donating oxygen substituent. The reaction between electrophilic malonate radical and nucleophilic vinyl ether is favored because the radical has a...
2.6K
Radical Autoxidation
3.4K
The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...
3.4K
Alkynes to Carboxylic Acids: Oxidative Cleavage
7.2K
Alkynes undergo oxidative cleavage in the presence of oxidizing reagents like potassium permanganate and ozone. The triple bond — one σ bond and two π bonds — is completely cleaved, and the alkyne is oxidized to carboxylic acids. When warm and basic aqueous potassium permanganate is used as an oxidizing agent, alkynes are first converted to carboxylate salts via an unstable α-diketone intermediate. Further, a mild acid treatment protonates the carboxylate anions...
7.2K
Free-Radical Chain Reaction and Polymerization of Alkenes
10.3K
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
10.3K
Radical Reactivity: Steric Effects
2.7K
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...
Along with electronic...
2.7K
Anionic Chain-Growth Polymerization: Overview
2.8K
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
2.8K

