PtとIrナノ粒子の対対置換触媒によるパラ水素誘導の偏化
Ronghui Zhou1, Evan W Zhao, Wei Cheng
1Department of Chemistry and ‡Department of Chemical Engineering, University of Florida , Gainesville, Florida 32611, United States.
Journal of the American Chemical Society
|January 29, 2015
まとめ
支えられた金属触媒は,水素化反応で意外にパラ水素誘発偏化 (PHIP) 信号を生成する. この発見により,パラヒドロゲン誘発的偏振を用いたバイオメディカルアプリケーションのための新しい超偏振方法が可能になる.
科学分野:
- カタリシス カタリシス カタリシス
- 有機化学 オーガニック・ケミストリー
- NMRスペクトロスコーピ NMRスペクトロスコーピ
背景:
- 偶数加法とランダム加法プロセスは,通常,水素化では区別がつかない.
- パラ水素誘発極化 (PHIP) は,スピン相関に依存し,触媒表面相互作用を決定的にします.
- サポートされた金属触媒は,H原子の急速な拡散とHoriuti-PolanyiメカニズムのためにPHIPを容易にすることは予想されませんでした.
研究 の 目的:
- サポートされた金属水素化触媒を使用して検出可能なPHIP NMR信号の驚くべき観測を調査する.
- サポートされたPtとIrナノ粒子が,特定のアルケンの対対置換反応を触媒化できることを示すために.
- バイオメディカル用途の多様な基板をハイパーポラライズするためのペアウェイズ置換PHIPの可能性を調査する.
主な方法:
- 支持されたプラチナ (Pt) とイリジウム (Ir) のナノ粒子を触媒として利用する.
- パラ水素とアルケーン (プロペン,3,3,3-トリフルオロプロペン) の混合物を触媒の上に流す.
- 密度行列のスペクトルシミュレーションを使用して,反応のステレオ選択性を分析し,対対の置換機構を確認します.
主要な成果:
- サポートされたPtおよびIrナノ粒子は,プロペンと3,3,3-トリフルオロプロペンの対対置換を触媒として作用することが示されました.
- 濃度のPHIP NMR信号は,パラ水素のスピン順序を組み込むことでアルケンの基板に生成されました.
- 双方向置換メカニズムのステレオ選択性は,スペクトルシミュレーションで成功裏に明らかにされました.
結論:
- サポートされた金属触媒は,これまでの予想に反して,実際に検出可能なPHIP NMR信号を生成することができます.
- サポートされたナノ粒子のペアウェイズ置換は,ハイパーポラライゼーションのための新しい経路を提供します.
- この方法は,生物医学画像と診断におけるPHIPに使用可能な基板の範囲を拡大する大きな可能性を秘めています.
関連する概念動画
Reduction of Alkenes: Catalytic Hydrogenation
15.2K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
15.2K
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.7K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
9.7K
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
4.1K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
4.1K
Heterogeneous Catalysis
129
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
129
Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
2.4K
Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation...
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation...
2.4K
Catalysis
32.6K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
32.6K


