表面化学における観衆制御選択性:Pdに対するアクロレイン部分水素化
Karl-Heinz Dostert1, Casey P O'Brien1, Francisco Ivars-Barceló1
1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
Journal of the American Chemical Society
|October 21, 2015
まとめ
アクロレインをプロペノールに選択的に水素化することは,改造されたパラジアム (Palladium) の表面で達成される. 独特のオックスプロピルスペクテーター層は,ほぼ完璧なCO結合選択性を可能にし,不飽和アルコールを形成します.
科学分野:
- 異質な触媒
- 表面科学
- 有機合成
背景:
- アクロレインの水素化は貴重な化学物質の生産に不可欠です.
- CC結合の水素化よりもCO結合の水素化の高い選択性を達成することは依然として困難です.
- パラジウム (Pd) ベースの触媒は,水素化反応のために広く研究されています.
研究 の 目的:
- モデルPd表面での選択的なアクロレイン水素化のメカニズムを調査する.
- 選択的なCO結合水素化を可能にする条件と表面種を特定する.
- 表面の変化が反応経路の方向づけに 果たす役割を理解する.
主な方法:
- 単一結晶 Pd ((""1) とサポートされた Pd ナノ粒子を用いたメカニズム研究.
- マルチ分子ビーム実験
- インサイト赤外線反射吸収光譜 (IRRAS)
主要な成果:
- COを不飽和アルコール (プロペノール) に水素化するためのほぼ100%の選択性は,Pdで達成された.
- オックスプロピルスペクテータのオーバーレイヤーによる表面修正は,選択性にとって不可欠である.
- オックスプロピルスペクテータとプロペノキシ反応性中間物質の識別
- 中間進化と産物形成の同時モニタリング
結論:
- アクロレインのCO結合の選択的水素化は,特定の表面条件下でPd{\displaystyle Pd{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }{\mathrm {P} }} }
- 表面媒介の観衆種は 触媒的選択性を効果的に制御できます
- この発見は,選択的水素化触媒の設計に根本的な洞察をもたらします.
関連する概念動画
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
4.0K
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...
4.0K
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.5K
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.
9.5K
Reduction of Alkenes: Catalytic Hydrogenation
14.9K
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...
14.9K
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
4.5K
The addition of a hydrogen halide to 1,3-butadiene gives a mixture of 1,2- and 1,4-adducts. Since more substituted alkenes are more stable, the 1,4-adduct is expected to be the major product. However, the product distribution is strongly influenced by temperature; low temperature favors the 1,2-adduct, whereas the 1,4-adduct is predominant at high temperature.
4.5K
Radical Anti-Markovnikov Addition to Alkenes: Overview
4.4K
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
4.4K
Regioselectivity of Electrophilic Additions-Peroxide Effect
11.7K
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.
11.7K


