透き通った金属有機構造体におけるスティルベンのダイアステロセレクティブ異質ブロミネーション
Simon C Jones1, Christina A Bauer
1School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30032, USA.
Journal of the American Chemical Society
|August 15, 2009
まとめ
ブロミンを用いた多孔性金属有機フレームワーク (MOF) の合成後の改変により,ダイアステロ選択的ブロミネーションが達成された. このMOFの改変により,構造の安定性が向上し,多孔ネットワーク内で制御された反応性が実証されました.
科学分野:
- マテリアルサイエンス 材料科学
- 化学 化学は化学です.
- クリスタルグラフィーです.
背景:
- メタル・オーガニック・フレームワーク (MOF) は,化学的変異のために調整可能な多孔性を提供します.
- 合成後の改変により,事前形成されたMOF構造の機能化が可能になります.
- MOFのスティルベンを含むリガンドは,電愛性添加反応に敏感である.
研究 の 目的:
- 特定のMOF,Zn(4) O(トランス-4,4'-スティルベン二炭酸塩酸) ((3) の合成後の改変を,ブロミネーションによって調査する.
- MOF内のブロミネーション反応のステレオ化学的結果とメカニズムを探求する.
- MOFの構造的整合性と安定性に対するブロミネーションの影響を評価する.
主な方法:
- ブロミン (Br2) とMOFの異質反応.
- 構造変化を分析するためのX線 difraktion (XRD).
- 陽性性と表面積を評価するための窒素 (N2) 吸収測定.
主要な成果:
- スティルベン二炭酸塩酸リガンドのダイアステロ選択的ブロミン化は,MOF内で発生しました.
- 硬いリガンド構造と多孔構造は,溶液のような反応性とステレオ制御を可能にしました.
- 部分的なブロミン化は,相互浸透したMOF構造の安定性を高めました.
結論:
- 合成後のブロミネーションは,高いステレオ選択性を持つMOFを改変するための有効な方法です.
- MOFの構造は,化学的変異を制御する上で重要な役割を果たします.
- ブロミネーションは,この特定の相互浸透したMOFの安定性を高め,頑丈な機能的な材料の可能性を示唆します.
さらに関連する動画
関連する概念動画
Radical Anti-Markovnikov Addition to Alkenes: Overview
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Radical Substitution: Allylic Bromination
In organic synthesis, the formation of products can be altered by changing the reaction conditions. For example, a dibromo addition product is formed when propene is treated with bromine at room temperature. In contrast, propene undergoes allylic substitution in non-polar solvents at high temperatures to give 3-bromopropene. In order to avoid the addition reaction, the bromine concentration must be kept as low as possible throughout the reaction. This can be achieved using N-bromosuccinimide...
Regioselectivity of Electrophilic Additions-Peroxide Effect
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Formation of Halohydrin from Alkenes
An alkene, such as propene, reacts with bromine in the presence of water to yield a halohydrin. Halohydrins contain a halogen and a hydroxyl group attached to adjacent carbons. When the halogen is bromine, it is called a bromohydrin, while a chlorohydrin has chlorine as the halogen.


