ストーン・ウェールズ・リアレンジメントは,過激派が推進した
Roger W Alder1, Jeremy N Harvey
1School of Chemistry, University of Bristol, Cantock's Close, Bristol, UK BS8 1TS. rog.alder@bris.ac.uk
Journal of the American Chemical Society
|February 26, 2004
まとめ
ストーン・ウェールズ再編成機構は,計算方法を用いて研究されました. 複雑なポリサイクル芳香炭化水素の場合は,単分子より,根幹促進経路がより可能性が高い.
科学分野:
- コンピューティング・ケミストリー
- 有機化学 オーガニック・ケミストリー
- マテリアルサイエンス 材料科学
背景:
- ストーン・ウェールズ再配列は,ポリサイクル芳香炭化水素 (PAH) の改変における重要な反応である.
- このメカニズムを理解することは,新しい炭素材料の設計と反応性の予測に不可欠です.
研究 の 目的:
- ビフローレニリデンのディベンゾ[g,p]クリセンへのストーン・ウェールズ再配置のメカニズムを解明する.
- 複雑なPAHsとフルレレンのためのラジカル促進経路の実現可能性を調査する.
主な方法:
- B3LYP/6-31G (d) レベルの理論を用いた密度関数計算.
- 提案された反応経路の活性化エネルギーの分析.
主要な成果:
- ホモアリル-サイクロプロピルカルビニル再配置のステップのシーケンスを持つラジカル促進メカニズムは,実験観察を正確に説明します.
- 単分子メカニズムは,非現実的に高い活性化エネルギーを示します.
- ラジカルが促進する経路は,ステリック阻害による活性化エネルギーの増加にもかかわらず,ダイインデノ[1,2,3,4-デフグ;1',2',3',4'-mnop]クリセンとC ((60)) に対して好ましいままです.
結論:
- 複雑なPAHにおけるストーン・ウェールズ再配置を理解するために,急進的に促進されたメカニズムは不可欠です.
- 計算による研究は,炭素ベースの材料の反応経路とエネルギーに関する貴重な洞察を提供します.
関連する概念動画
Radical Formation: Overview
A bond can be broken either by heterolytic bond cleavage to form ions or homolytic bond cleavage to yield radicals. A fishhook arrow is used to represent the motion of a single electron in homolytic bond cleavage. There are two main sources from which radicals can be formed:
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...
Radical Formation: Homolysis
A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.
Radical Formation: Abstraction
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...
Radical Formation: Addition
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 unpaired...
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...
Radical Formation: Elimination
Another method of radical formation is the elimination process. It is the opposite of the addition route and is driven by the instability of the radical. For example, as depicted in Figure 1, dibenzoyl peroxide yields a pair of unstable radicals upon homolysis. Given its instability, this radical spontaneously undergoes elimination via a C–C bond cleavage to form a relatively more stable phenyl radical. The mechanism involves cleavage of the bond between the α and β positions with respect to...
Radical Halogenation: Stereochemistry
Stereochemistry is the study of the different spatial arrangements of atoms in a given molecule. The stereochemistry of radical halogenations can be understood from three different situations:
Halogenation to form a new chiral center:
Halogenation to form a new chiral center:


