水素同位体効果と水性オゾンとペロクソンの分解の仕組み
Timothy M Lesko1, A J Colussi, Michael R Hoffmann
1W. M. Keck Laboratories, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|April 1, 2004
まとめ
水素過酸化物とは
科学分野:
- 環境化学 環境化学
- 酸化化学 オキシデーション化学
背景:
- 水性オゾン (O3) の反応性は過酸化水素 (H2O2) によって強化されますが,その背後にあるメカニズムは不明です.
- オゾン分解には,ヒドロキシル (.OH) と超酸化物 (.O2-) のラジカルを含む根幹鎖メカニズムが,H2O2.2の存在下でのオゾン分解のためにしばしば提案されている.
研究 の 目的:
- 水性オゾンと過酸化水素の反応機構を調査する.
- ペロクソン系における,ラジカル対非ラジカル経路の役割を明らかにする.
主な方法:
- H2O/D2O溶媒の同位体効果を用いた運動研究.
- 実験的なオゾン分解速度の比較と,過激連鎖メカニズムからの予測.
主要な成果:
- ラジカルメカニズムはH2Oにおけるオゾン分解を正確に予測するが,ペロゾン (O3 + H2O2) では過大評価する.
- 溶剤デュテレーションの実験では,オゾン+水酸化物アニオン (HO2-) 反応から基質産物が生成されないことが示されています.
- ペロキソン系における大きな運動同位体効果 (KIE) は,オゾンとHO2−の間の非急性,水素移転反応を示し,HO3−とO2−を形成している.
結論:
- ペロクソン系におけるH2O2によるオゾン反応性の強化は,主に非急性水素移転機構によって引き起こされ,急性連鎖反応によって引き起こされない.
- 形成されたHO3-種は,最近特定された殺菌性三酸化物に関連している可能性があります.
さらに関連する動画
11:38In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework
Published on: February 1, 2020
08:30A Complete Method for Evaluating the Performance of Photocatalysts for the Degradation of Antibiotics in Environmental Remediation
Published on: October 6, 2022
関連する概念動画
02:30Water: A Bronsted-Lowry Acid and Base
The reaction between a Brønsted-Lowry acid and water is called acid ionization. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions:
03:24Common Ion Effect
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide:
04:01Factors Affecting Solubility
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Chȃtelier’s principle. Consider the dissolution of silver iodide:
02:58Balancing Redox Equations
Electrochemistry is the science involved in the interconversion of electrical and chemical reactions. Such reactions are called reduction-oxidation, or redox reactions. These important reactions are defined by changes in oxidation states for one or more reactant elements and include a subset of reactions involving the transfer of electrons between reactant species. Electrochemistry as a field has evolved to yield sufficient insights on the fundamental principles of redox chemistry and multiple...
01:20Radical Autoxidation
The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...
01:28Microbial Bioremediation of Pesticides
Pesticides often feature structurally complex chemical architectures, incorporating halogen groups and multiple aromatic rings. These characteristics confer high chemical stability, rendering many pesticides resistant to natural degradation processes. This resistance poses significant environmental concerns, as persistent pesticide residues can accumulate in ecosystems and affect non-target organisms.Despite the inherent stability of many pesticides, certain microorganisms possess the metabolic...