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Reaction mechanism

About: Reaction mechanism is a(n) research topic. Over the lifetime, 26264 publication(s) have been published within this topic receiving 668528 citation(s).
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Journal ArticleDOI
Abstract: We present a method for calculating the stability of reaction intermediates of electrochemical processes on the basis of electronic structure calculations. We used that method in combination with detailed density functional calculations to develop a detailed description of the free-energy landscape of the electrochemical oxygen reduction reaction over Pt(111) as a function of applied bias. This allowed us to identify the origin of the overpotential found for this reaction. Adsorbed oxygen and hydroxyl are found to be very stable intermediates at potentials close to equilibrium, and the calculated rate constant for the activated proton/electron transfer to adsorbed oxygen or hydroxyl can account quantitatively for the observed kinetics. On the basis of a database of calculated oxygen and hydroxyl adsorption energies, the trends in the oxygen reduction rate for a large number of different transition and noble metals can be accounted for. Alternative reaction mechanisms involving proton/electron transfer to ...

5,473 citations

Journal ArticleDOI
13 Jun 2007-Chemical Reviews
TL;DR: Reaction Mechanism, Synthesis of Urea and Urethane Derivatives, and Alcohol Homologation 2382 10.1.
Abstract: 4.3. Reaction Mechanism 2373 4.4. Asymmetric Synthesis 2374 4.5. Outlook 2374 5. Alternating Polymerization of Oxiranes and CO2 2374 5.1. Reaction Outlines 2374 5.2. Catalyst 2376 5.3. Asymmetric Polymerization 2377 5.4. Immobilized Catalysts 2377 6. Synthesis of Urea and Urethane Derivatives 2378 7. Synthesis of Carboxylic Acid 2379 8. Synthesis of Esters and Lactones 2380 9. Synthesis of Isocyanates 2382 10. Hydrogenation and Hydroformylation, and Alcohol Homologation 2382

2,899 citations

Journal ArticleDOI
Abstract: The present status of knowledge of the gas-phase reactions of inorganic Ox, HOx and NOx species and of selected classes of volatile organic compounds (VOCs) [alkanes, alkenes, aromatic hydrocarbons, oxygen-containing VOCs and nitrogen-containing VOCs] and their degradation products in the troposphere is discussed. There is now a good qualitative and, in a number of areas, quantitative understanding of the tropospheric chemistry of NOx and VOCs involved in the photochemical formation of ozone. During the past five years much progress has been made in elucidating the reactions of alkoxy radicals, the mechanisms of the gas-phase reactions of O3 with alkenes, and the mechanisms and products of the OH radical-initiated reactions of aromatic hydrocarbons, and further progress is expected. However, there are still areas of uncertainty which impact the ability to accurately model the formation of ozone in urban, rural and regional areas, and these include a need for: rate constants and mechanisms of the reactions of organic peroxy ( R O 2 ) radicals with NO, NO3 radicals, HO2 radicals and other R O 2 radicals; organic nitrate yields from the reactions of R O 2 radicals with NO, preferably as a function of temperature and pressure; the reaction rates of alkoxy radicals for decomposition, isomerization, and reaction with O2, especially for alkoxy radicals other than those formed from alkanes and alkenes; the detailed mechanisms of the reactions of O3 with alkenes and VOCs containing >CC

2,367 citations

Journal ArticleDOI
01 Jan 1993-
TL;DR: The rate constant for the reaction of NO with .O2- was determined to be (6.7 +/- 0.9) x 10(9) l mol-1 s-1, considerably higher than previously reported.
Abstract: The rate constant for the reaction of NO with ·O2− was determined to be (6.7 ± 0.9) × 109 1 mol−1 s−1, considerably higher than previously reported. Rate measurements were made from pH 5.6 to 12.5 ...

2,066 citations

Journal ArticleDOI
Abstract: Hydroxyl and other oxygen-containing radicals are known to be present during the degradation of organic water pollutants in illuminated TiO2 photocatalyst slurries. It is proposed that the hydroxyl radical, OH·, is the primary oxidant in the photocatalytic system. Four possible mechanisms are suggested, all based on OH· attack of the organic reactant. The cases of reaction on the surface, in the fluid, and via a Rideal mechanism are shown to yield expressions similar to Langmuir-Hinshelwood (LH) rate forms. Compared with traditional LH constants, the derived kinetic parameters represent fundamentally different reactions and properties. A rate parameter independent of organic reactant is predicted by the model and substantiated by experimental degradation data. On the basis of these model results, the kinetic parameters for the photocatalytic degradation may be estimated from data on the photocatalyst's physical properties, the knowledge of electron-hole recombination and trapping rates, and the values of second-order reaction rate constants for hydroxyl radicals.

1,846 citations

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Topic's top 5 most impactful authors

Ik-Hwan Um

58 papers, 1K citations

Alexander M. Mebel

33 papers, 549 citations

Takeshi Endo

28 papers, 555 citations

Tapio Salmi

27 papers, 437 citations

Min Shi

27 papers, 507 citations