水中のフッ素基のアルケーン加減反応の絶対速度定数
L Zhang1, W R Dolbier, B Sheeller
1Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA.
Journal of the American Chemical Society
|May 30, 2002
まとめ
水溶性アルケンのフッ素基添加率の定数を測定した. 水中の増加率は,この重要な化学反応の移行状態の極性溶媒の安定化を示唆しています.
科学分野:
- 物理化学 物理化学
- 有機化学 オーガニック・ケミストリー
- 化学動力学 化学動力学
背景:
- ラジカル添加反応の理解は,有機合成とポリマー化学において極めて重要です.
- 反応機構,特に移行状態の安定化に対する溶媒の極性の影響は,重要な研究分野である.
- フッ素ラジカルとその反応性は,化学的変換においてユニークな課題と機会を提示します.
研究 の 目的:
- 水溶性アルケーンに電性フッ素ラジカル (*R(f) SO(3) ((-)) を加えるための絶対速度定数を定量化します.
- アルケンの溶解性および反応性に対するイオンおよび炭酸塩基置換物の影響を調査する.
- 極性溶媒 (水) と非極性有機溶媒の反応性を比較する.
主な方法:
- ラジカルを生成し,加法反応を開始するために,レーザーフラッシュ光分解が採用されました.
- 反応運動をモニタリングし,速度定数を決定するために,光譜技術が使用されました.
- 異なるイオン置換剤を伴う水溶性アルケンのシリーズが合成され,利用されました.
主要な成果:
- 試験したアルケンの*R(f) SO(3)(-) 基素加減の絶対速度定数は,水で測定に成功しました.
- 観測された速度定数は,非極性有機溶媒における同様の反応と比較して (3〜9倍) 大きく高かった.
- アルケンの上にあるイオン性炭酸塩基置換物の存在は,アルケンの水溶性および反応性に影響を与えた.
結論:
- 水中の反応速度の上昇は,極性溶媒による極性移行状態の安定化に起因する.
- 水が有電荷または極性中間物質を溶解および安定させる能力は,これらの急性添加反応の加速に重要な役割を果たします.
- これらの発見は,環境および生物学的アプリケーションに関連する水中媒体におけるフッ素基反応のメカニズムに関する貴重な洞察を提供します.
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