cis,cis-[(bpy) 2Ru(OH2) ]2O4+イオンによって触媒化された水の酸化メカニズム
Hiroshi Yamada1, William F Siems, Tohru Koike
1Department of Chemistry, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239, Japan.
Journal of the American Chemical Society
|August 5, 2004
まとめ
この研究は,ルテニウム複合体によって触媒化された水の酸化のための2つの経路を明らかにしています. 1つの経路はルテニル酸素と溶媒水を使用し,もう1つは溶媒水分子のみを使用します.
科学分野:
- 無機化学 無機化学とは
- カタリシス カタリシス カタリシス
- 水酸化による水酸化.
背景:
- cis,cis-[(bpy) ((2) Ru (((III) ((OH2)) ]2O4+マイクロオクソ二次調整複合体は,水の酸化のための効果的な触媒である.
- 水の酸化は,エネルギー変換と生物学的システムにおける重要なプロセスです.
研究 の 目的:
- cis,cis-[(bpy) (((2) Ru(III) (((OH2) ]2O4+複合体によって触媒化された水の酸化の反応経路とメカニズムを解明する.
- 水酸化過程における溶媒と触媒である酸素の役割を調査する.
主な方法:
- 18Oラベル付き触媒と質量スペクトロメトリーを使用して,O2の同位体分布を分析しました. 製品.
- 測定された表面活性化パラメータ (DeltaH++,DeltaS++) と溶媒デウテリウム運動同位体効果 (KIE).
主要な成果:
- 2つの異なる反応経路がO2形成のために特定されました.
- パスウェイ1はルテニル酸素と溶媒水を使用し,パスウェイ2は溶媒水のみを使用しています.
- 動的同位体効果とアクティベーションパラメータは,水添加を決定的なステップとしてコヴァレンント水素を形成することを示唆しています.
結論:
- H2Oを添加してコヴァレンント水素を形成するメカニズムが提案されていることは,既知の2つの経路にとって非常に重要です.
- 経路1は,隣接するルテニル酸素原子の間でH2Oの添加を伴う.
- 経路2は,ルテニル酸素にHを添加し,ビピリジン環にOHを添加する.
関連する概念動画
Catalysis
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.
Hydroboration-Oxidation of Alkenes
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.
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
Aldehydes and Ketones to Alkenes: Wittig Reaction Mechanism
The Wittig reaction, which converts aldehydes or ketones to alkenes using phosphorus ylides, proceeds through a nucleophilic addition‒elimination process.
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
Heterogeneous Catalysis
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...


