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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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Journal ArticleDOI
TL;DR: In this article, a theoretical model of solid oxide electrolysis cells considering the heterogeneous elementary reactions, electrochemical reactions and the transport process of mass and charge is applied to study the relative performance of H 2 O electrolysis, CO 2 electrolysis and CO 2 /H 2 O co-electrolysis.

27 citations

Journal ArticleDOI
TL;DR: In this paper, the authors consider reaction paths for two prototypical chemical reactions: Li + HF, an electron-transfer reaction, and OH + H2, an abstraction reaction.
Abstract: The concept of a reaction path which continuously describes the transformation of reactants to products is firmly embedded in the lore of chemistry. A formal definition of the reaction path for a general molecular system was proposed by Fukui in 1970 as the path of steepest descent in mass-weighted cartesian coordinates from the transition state to reactants in one direction and to products in the other. In 1980 Miller, Handy and Adams advanced a formal theory of reaction dynamics based on harmonic fluctuations about the reaction path. We report reaction paths for two prototypical chemical reactions: Li + HF, an electron-transfer reaction, and OH + H2, an abstraction reaction. In the first we consider the connection between the energetic terms in the reactions path Hamiltonian and the electronic changes which occur upon reaction. In the second reaction we consider the treatment of vibrational effects in chemical reactions in the reaction-path formalism.

26 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the quantum yield of free AQ- radical anion formation is governed by the interplay of forward, reverse and back electron transfer (ET) quenching reactions of electronically excited *Ru(bpy)32+ in acetonitrile.
Abstract: In the electron transfer (ET) quenching reactions of electronically excited *Ru(bpy)32+ in acetonitrile an increase of the rate constant kq is observed in the series of 2-methyl-, 1-chloro-, and 1-nitro-anthraquinone as quenchers. If alkali salts are used as supporting electrolytes the AQ- radical anions are found to form specific associates with the alkali cations. In the presence of non-associating tetraalkylammonium salts the system follows the predictions of Marcus theory. Numerical methods are developed which allow the determination of the rate constants of the conventional reaction scheme. This analysis shows that the quantum yield of free AQ- radical anion formation is governed by the interplay of forward, reverse and back ET. Negative activation enthalpies are found for the activation controlled quenching reactions. From the numerical analysis of the system of rate constants it is inferred that this phenomenon is due to the elementary ET step in the reaction sequence. We discuss the pre-equilibrium and elementary reaction models for reactions with negative activation enthalpy and present, to our knowledge, the first example of successful discrimination between them.

26 citations

Journal ArticleDOI
TL;DR: This work demonstrates the continuous, acceptorless dehydrogenation of alcohols to carbonyl compounds over heterogeneous catalysts in the absence of oxidants, bases or acceptor molecules, and identifies the basic kinetic parameters of the reaction, allowing some of the elementary reaction steps to be identified.
Abstract: Although the selective oxidation of alcohols to carbonyl compounds is a critical reaction, it is often plagued by several challenges related to sustainability. Here, the continuous, acceptorless dehydrogenation of alcohols to carbonyl compounds over heterogeneous catalysts was demonstrated, in the absence of oxidants, bases or acceptor molecules. In addition to improving selectivity and atom efficiency, the absence of an acceptor resulted in the co‐production of molecular H2, a clean energy source, and permitted dehydrogenation to proceed at >98 % selectivity at turnover frequency values amongst the highest in the literature. Moreover, excellent durability was observed during continuous operation over 48 h, reaching space‐time yields of 0.683 g(product) mL−1 h−1, better than the state of the art by over two orders of magnitude. Alongside these breakthroughs, the basic kinetic parameters of the reaction were also determined, allowing some of the elementary reaction steps to be identified.

26 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the reaction of the dicarbon molecule (C2) in its + electronic ground state with hydrogen cyanide HCN(X^(1)Σ^+) in a crossed molecular beam setup to untangle the formation of the cyanoethynyl radical (CCCN) in hydrocarbon-rich atmospheres of planets and their moons such as Titan.
Abstract: The reaction of the dicarbon molecule (C2) in its ^(1)Σ_(g) + electronic ground state with hydrogen cyanide HCN(X^(1)Σ^+) is investigated in a crossed molecular beam setup to untangle the formation of the cyanoethynyl radical CCCN(X^(2)Σ^+) in hydrocarbon-rich atmospheres of planets and their moons such as Titan. Combined with electronic structure and rate theory calculations, we show that this elementary reaction is rapid, has no entrance barriers, and yields CCCN via successive rearrangements of the initial HC_(3)N collision complex to the cyanoacetylene intermediate (HCCCN) followed by unimolecular decomposition of the latter without exit barrier. New photochemical models imply that this radical could serve as a key building block to form more complex molecules as observed in situ by the Cassini spacecraft, ultimately leading to organic aerosol particles, which make up the orange-brownish haze layers in Titan's atmosphere.

26 citations


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