陽子化同位体特異的なイオン-分子ラジカル反応
Oisin J Shiels1, Samuel J P Marlton1, Adam J Trevitt1
1Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, New South Wales, Australia.
Journal of the American Chemical Society
|June 20, 2023
まとめ
クイナゾリンカチオンのプロトネーション部位の変化は,エチレンとのラジカル反応性を有意に変化させる. 直接結合ではなく,空間を通る静電効果がこれらの違いを説明し,分析には高度な量子化学的方法が必要です.
科学分野:
- 物理化学
- 化学運動学
- コンピュータ化学
背景:
- ディストン基離子はいろいろな化学プロセスにおける重要な中間物質です.
- 反応機構の解明には,陽子化部位が反応性に影響を及ぼすことを理解することが不可欠である.
- ガス相の研究は,特定の化学効果を分離するための簡素化された環境を提供します.
研究 の 目的:
- エチレンとキナゾリンカチオンプロトネーションイソマーのガス相反応運動を独立に測定する.
- 陽子化部位の変化が 根子の反応性に影響を及ぼすことを調べる
- これらの反応性の違いを左右する根本的な要因,特に静電効果を解明する.
主な方法:
- イオン移動性フィルタリングを使用して,プロトネーション同位体を分離した.
- レーザー装備の四極イオントラップ質量スペクトロメトリーは,運動測定を可能にしました.
- 理論的な計算には二重混合密度関数理論が用いられました.
主要な成果:
- 2つのプロトネーション同位体に対して,異なるガス相反応動力学が観察された.
- プロトネーション部位の変化は,エチレンに対するラジカル反応性に大きな変化をもたらした.
- 空間を通る静電相互作用は,反応性の差異の主な要因として特定された.
結論:
- クイナゾリンカチオンにおけるプロトネーションの位置は,その根幹の反応性に大きく影響する.
- 空間間相互作用によって媒介される静電効果は,反応結果を決定する上で極めて重要です.
- これらの長距離効果を 正確にモデル化し説明するには 先進的な計算方法が必要である.
関連する概念動画
01:02Radical Reactivity: Electrophilic Radicals
1.9K
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...
1.9K
01:11Radical Reactivity: Overview
2.1K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.1K
01:16Radical Reactivity: Nucleophilic Radicals
2.1K
Radicals adjacent to electron-donating groups are called nucleophilic radicals. These radicals readily react with electrophilic alkenes. The SOMO–LUMO interactions are the driving force for the reaction, where the high-energy SOMO of the electron-rich, nucleophilic radicals interacts with the low-energy LUMO of the electron-deficient, electrophilic alkenes. Such SOMO–LUMO interactions are the basis of reactive radical traps, affecting the selectivity in radical reactions. For...
2.1K
00:47Radical Formation: Addition
1.7K
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
1.7K
01:10Radical Reactivity: Steric Effects
1.9K
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...
1.9K
00:47Radical Formation: Abstraction
3.5K
The electron of an atom can be abstracted from a compound by a relatively unstable radical to generate a new radical of relatively greater stability. For example, an initiator which forms radicals by homolysis can abstract a suitable species like a hydrogen atom or a halogen atom from a compound to generate a new radical. This ability of radicals to propagate by abstraction is a crucial feature of radical chain reactions.
Even though homolysis produces radicals, it is different from radical...
Even though homolysis produces radicals, it is different from radical...
3.5K