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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: In this paper, a unified reaction valley approach (URVA) is used to investigate the mechanism of the reaction H2CCH2======+ FH → H3C-CH2F (reaction I) at different levels of theory (HF, MP2 and CCSD(T)) with different basis sets (6-31G(d,p), 6-311 +============+ G(3df,3dp) and cc-pVTZ).
Abstract: The unified reaction valley approach (URVA) is used to investigate the mechanism of the reaction H2CCH2
+ FH → H3C–CH2F (reaction I) at different levels of theory (HF, MP2 and CCSD(T)) with different basis sets (6-31G(d,p), 6-311 +
+ G(3df,3dp) and cc-pVTZ). URVA is based on the reaction path Hamiltonian, the intrinsic
reaction coordinate, and the characterization of normal modes, reaction path vector and curvature vector
in terms of generalized adiabatic modes associated with internal parameters that are used to describe the
reaction complex. In addition, URVA combines the investigation of the harmonic reaction valley with the analysis of attractive and repulsive forces exerted on the nuclei by analyzing the changes of the electron density distribution
along the reaction path. It is shown that reaction I involves two different chemical processes: (a) the simultaneous FH bond cleavage and CH bond formation leading to an intermediate structure with ion-pair
character and (b) the formation of a CF bond and, by this, the final product. The properties of the reaction
complex suggest the possibility that a hidden intermediate formed in process (a), which upon a change in the reaction conditions (environment, substitution pattern) can convert into a real intermediate (in solution: solvated
ion pairs). Using the results of the URVA analysis of reaction I predictions with regard to the occurrence
of hidden intermediates in related addition/cycloaddition reactions are made.
39 citations
TL;DR: In this article, linear free energy relationships (LFERs) were developed to predict the rate constants for aqueous phase radical reactions. But the LFERs were not applied to other environmental processes in which radical-involved reactions occur.
Abstract: Aqueous phase advanced oxidation processes (AOPs) produce hydroxyl radicals (HO•) which can completely oxidize electron rich organic compounds. The proper design and operation of AOPs require that we predict the formation and fate of the byproducts and their associated toxicity. Accordingly, there is a need to develop a first-principles kinetic model that can predict the dominant reaction pathways that potentially produce toxic byproducts. We have published some of our efforts on predicting the elementary reaction pathways and the HO• rate constants. Here we develop linear free energy relationships (LFERs) that predict the rate constants for aqueous phase radical reactions. The LFERs relate experimentally obtained kinetic rate constants to quantum mechanically calculated aqueous phase free energies of activation. The LFERs have been applied to 101 reactions, including (1) HO• addition to 15 aromatic compounds; (2) addition of molecular oxygen to 65 carbon-centered aliphatic and cyclohexadienyl radicals; (3) disproportionation of 10 peroxyl radicals, and (4) unimolecular decay of nine peroxyl radicals. The LFERs correlations predict the rate constants within a factor of 2 from the experimental values for HO• reactions and molecular oxygen addition, and a factor of 5 for peroxyl radical reactions. The LFERs and the elementary reaction pathways will enable us to predict the formation and initial fate of the byproducts in AOPs. Furthermore, our methodology can be applied to other environmental processes in which aqueous phase radical-involved reactions occur.
39 citations
TL;DR: In this article, the effect of CO2 dilution on laminar premixed n-heptane/air flames were performed via the outwardly propagating spherical flames and the simulation of one-dimensional planar flames.
39 citations
Book•
01 Sep 1982
TL;DR: In this paper, the physical foundation of the empirical relationship between different types of reaction types and their properties is discussed. But the physical foundations of empirical relations are not explicitly discussed in this paper.
Abstract: Introduction General Reaction Types Homogeneous Catalyzed Reactions Dependence of Reaction Rate on Concentration: Systematic Kinetic Analysis Dependence of Reaction Rate on Temperature Dependence of Reaction Rate on Pressure Dependence of Reaction Rate on Solvent Dependence of Reaction Rate on Substituent The Physical Foundation of the Empirical Correlations References Subject Index.
39 citations
TL;DR: The thermal isomerization of cy clopropane to propylene is a homogeneous unimolecular reaction at 490°C and at pressures down to 0·007 cm as mentioned in this paper.
Abstract: The thermal isomerization of cy clopropane to propylene is a homogeneous unimolecular reaction at 490° C and at pressures down of 0·007 cm. The rate constant of the unimolecular reaction falls off by a factor of ten as the pressure in the reaction system is decreased from 8·4 to 0·007 cm. The results are compared with various theories of quasi-unimolecular reactions. The addition of a non-reacting gas to the system counteracts the falling off. The relative efficiencies of a number of gases for maintaining the unimolecular rate constant have been measured.
39 citations