異質なRh-WOxペアサイト触媒の二機能水酸化
Insoo Ro1,2,3, Ji Qi1,3, Seungyeon Lee3,4
1Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA.
Nature
|September 7, 2022
まとめ
原子的に分散したロジウム・タングステン酸化物 (Rh-WOx) のペアサイトは,エチレン水溶解のための二機能触媒を可能にします. これらの支援された触媒は,工業用途の均質な触媒を模倣して,高い選択性と活性を示しています.
科学分野:
- 異質な触媒
- 表面科学
- 有機金属化学
背景:
- バイ機能的活性サイトは,金属触媒反応に不可欠であり,触媒サイクルにおける異なるステップを容易にする.
- 均質な触媒のために確立されているが,構造的複雑性とダイナミックな再構築のためにサポートされた金属上のこれらのサイトを明らかにすることは困難である.
- サポートされた金属触媒は,しばしば金属酸化物インターフェースを潜在的な二機能サイトとして含みます.
研究 の 目的:
- サポートされた金属触媒の二機能メカニズムの研究における課題を克服する.
- 簡素化されたモデルシステムを合成し,特徴づけること: サポートされた,原子的に分散したロジウム-タングスティン酸化物 (Rh-WOx) のペアサイト.
- 双機能反応機構の理論的シミュレーションと実験的運動を相関させる.
主な方法:
- 支持された,原子的に分散したRh-WOxペアサイト触媒の合成
- ガス相エチレンの水酸化実験
- 最初の原理に基づいたマイクロキネティックシミュレーションは,実験的なキネティックと相関しています.
- アクティブサイト構造と触媒性能の特徴
主要な成果:
- Rh-WOxペアサイトは,二機能メカニズムを通じてエチレン水酸化を触媒化する.
- このメカニズムは,Rh補助によるWOx減量,WOxからRhへのエチレン転送,およびインターフェイスでのH2解離を含む.
- プロパナルcm−3h−1の産物形成率で95%以上の選択性を達成した.
- この簡素化されたペアサイトシステムに対する平均フィールドモデリングの適性を実証した.
結論:
- サポートされた酸化物ペアサイトは,二機能反応機構を効果的に可能にします.
- これらのサイトは,均質な触媒に匹敵する高い活性と選択性を提供します.
- このアプローチは,工業プロセスのための高度な異質な触媒の設計への道筋を提供します.
さらに関連する動画
関連する概念動画
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.4K
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...
3.4K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.4K
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...
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...
8.4K
03:08Hydroboration-Oxidation of Alkenes
8.7K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
8.7K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
8.0K
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.
8.0K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
18.7K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
18.7K
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
3.5K
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
3.5K