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Elementary reaction

About: Elementary reaction is a research topic. Over the lifetime, 2972 publications have been published within this topic receiving 76110 citations.


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TL;DR: A group contribution method (GCM) is developed to predict the aqueous phase HO* rate constants for the following reaction mechanisms; this accuracy may be acceptable for model predictions of the advanced oxidation processes (AOPs) performance, depending on how sensitive the model is to the rate constants.
Abstract: The hydroxyl radical (HO•) is a strong oxidant that reacts with electron-rich sites of organic compounds and initiates complex chain mechanisms. In order to help understand the reaction mechanisms, a rule-based model was previously developed to predict the reaction pathways. For a kinetic model, there is a need to develop a rate constant estimator that predicts the rate constants for a variety of organic compounds. In this study, a group contribution method (GCM) is developed to predict the aqueous phase HO• rate constants for the following reaction mechanisms: (1) H-atom abstraction, (2) HO• addition to alkenes, (3) HO• addition to aromatic compounds, and (4) HO• interaction with sulfur (S)-, nitrogen (N)-, or phosphorus (P)-atom-containing compounds. The GCM hypothesizes that an observed experimental rate constant for a given organic compound is the combined rate of all elementary reactions involving HO•, which can be estimated using the Arrhenius activation energy, Ea, and temperature. Each Ea for thos...

207 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of the evolution of the NO-CO reaction on rh and present the data for the elementary reaction steps, obtained primarily on Rh(1 1 1) at UHV conditions.

206 citations

Journal ArticleDOI
TL;DR: In this article, a detailed kinetic model is derived using Hougen-Watson rate expressions for the Fischer-Tropsch reactions and the water gas shift reaction on a precipitated promoted iron catalyst.
Abstract: A detailed kinetic model is derived using Hougen-Watson rate expressions for the Fischer-Tropsch reactions and the water gas shift reaction on a precipitated promoted iron catalyst. The model discrimination and the parameter estimation are performed according to the integral method of kinetic analysis on experiments described in part 1 of this series. In the construction of the kinetic model, the information gained from in situ catalyst characterization is used. The model proposed assumes different active sites for the water gas shift reaction on one side and for the reactions leading to n-paraffins and 1-olefins on the other side. The rate expressions for the hydrocarbon-forming reactions are based on elementary reactions corresponding to the carbide mechanism, in the assumption that two kinds of elementary reactions, the ones describing the adsorption of carbon monoxide and these describing the desorption of the hydrocarbon products, are not at equilibrium. The assumption that the active sites are almost completely occupied with surface hydrocarbon intermediates greatly simplified the kinetic expressions. The rate expression for the water gas shift reaction is based on elementary reactions involving a formate surface intermediate. The two-site reaction describing the formation of the formate intermediate is proposed to be rate determining. Themore » values of the activation energies derived correspond well with data reported in the literature.« less

203 citations

Journal ArticleDOI
01 Jan 2016-Science
TL;DR: It is demonstrated that vinyl boronic ester ate complexes, prepared by combining organoboronates and organolithium reagents, engage in palladium-induced metallate rearrangement wherein 1,2-migration of an alkyl or aryl group from boron to the vinyl α-carbon occurs concomitantly with C–Pd σ-bond formation.
Abstract: Transition metal catalysis plays a central role in contemporary organic synthesis. Considering the tremendously broad array of transition metal-catalyzed transformations, it is remarkable that the underlying elementary reaction steps are relatively few in number. Here, we describe an alternative to the organometallic transmetallation step that is common in many metal-catalyzed reactions, such as Suzuki-Miyaura coupling. Specifically, we demonstrate that vinyl boronic ester ate complexes, prepared by combining organoboronates and organolithium reagents, engage in palladium-induced metallate rearrangement wherein 1,2-migration of an alkyl or aryl group from boron to the vinyl α-carbon occurs concomitantly with C-Pd σ-bond formation. This elementary reaction enables a powerful cross-coupling reaction in which a chiral Pd catalyst merges three simple starting materials-an organolithium, an organoboronic ester, and an organotriflate-into chiral organoboronic esters with high enantioselectivity.

201 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202321
202229
202185
202088
201971
201871