なぜフルオリン化により,バイサイクロ[2.2.0]ヘックス-1(4) -エネは二極化に安定するのでしょうか? 計算によって答えが得られます
G Robert Shelton1, David A Hrovat, Haiyan Wei
1Department of Chemistry, University of North Texas, P.O. Box 305070, Denton, Texas 76203-5070, USA.
Journal of the American Chemical Society
|September 7, 2006
まとめ
B3LYPの計算は,なぜバイサイクロ[2.2.0]ヘックス-1(4) -エネが容易に二酸化されるが,そのフルオリン化アナログはそうしないのかを明らかにする. フッ素化によりパイ結合が強化され,ステリック効果と電子効果による二酸化が阻害されます.
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
- 物理化学 物理化学
背景:
- Bicyclo[2.2.0]hex-1(4) -ene (1a) は容易に分解される.
- Perfluorobicyclo[2.2.0]hex-1(4) -ene (1b) の二酸化は観察されていない.
- これらの反応に影響を与える要因を理解することは,反応性の予測に極めて重要です.
研究 の 目的:
- 1a と 1b の異なる二分化行動の背後にある理由を解明する.
- 観測された反応性の差異に対するエネルギーの貢献を定量化する.
主な方法:
- B3LYP 密度関数理論の計算.
- コンピューティングの厳格性のために2つの異なるベースセットを使用しました.
- 分析された反応エンタルピー,中間生成,および循環エネルギー.
主要な成果:
- 1aの二酸化はエクソサーミック (37.2 kcal/mol) で,1bの二酸化はエンドサーミック (7.4 kcal/mol) である.
- 1bにおけるパイ結合は1a (kcal/molの差は16±1) よりも著しく強い.
- フッ素の影響には,ハイパーコンジュガーションと,ラジカルセンターとの不良なシン・ペリプラナー相互作用が含まれています.
結論:
- 1bにおけるハイパー結合とフッ素原子からのステリック/電子反発による強化されたパイ結合強さは,その二分化を防ぐ.
- 1a と 1b の二酸化反応の間の計算されたエネルギー差は 44.6 kcal/mol です.
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