Kinetics of hydrogen-transfer isomerizations of butoxyl radicals

Abstract

Five isomerization reactions involving intramolecular hydrogen-transfer in butoxyl radicals have been studied using variational transition state theory with small curvature tunneling. A set of best estimates of barrier heights and reaction energies for these five reactions was obtained by using coupled cluster theory including single and double excitations with a quasiperturbative treatment of connected triple excitations and a basis set extrapolated to the complete basis set limit plus core-valence correlation contributions and scalar relativistic corrections. This work predicts high-pressure limiting rate constants of these five reactions over the temperature range 200-2500 K and clarifies the available experimental data from indirect measurements. This study shows the importance of performing rate calculations with proper accounting for tunneling and torsional anharmonicity. We also proposed two new models for use in fitting rate constants over wide ranges of temperature.

Understanding the catalytic role of oxalic acid in the SO<sub>3</sub> hydration to form H<sub>2</sub>SO<sub>4</sub> in the atmosphere

“…et al, 2001;Cameron et al, 2002;Steckler et al, 1997;Atkinson et al, 2006). Some addition (Steudel, 1995;Williams et al, 1983;Courmier et al, 2005;Zhang and Zhang, 2002), decomposition (Rayez et al, 2002;Kumar and Francisco, 2015;Gutbrod et al, 1996), isomerization (Zheng and Truhlar, 2010;Atkinson, 2007), and abstraction reactions (Ji et al, 2013;Ji et al, 2017) also are the important HAT reaction in the atmosphere. These atmospheric HAT reactions have a main feature that two-point hydrogen bond can occur and can facilitate hydrogen atom transfer (Kumar et al, 2016).…”

The behavior of active diffusiophoretic suspensions: An accelerated Laplacian dynamics study

“…The M08-HX functional has been found to have outstanding performance for hydrogen-atom transfer barrier heights in application after application. [302][303][304][305][306][307][308][309][310][311] We also note the good performance of the GAM functional, 196 which is obtained at the gradient approximation level, without kinetic energy density and without nonlocal exchange; GAM, which denotes gradient approximation for molecules, uses the same mathematical form as the N12 functional, 195 which was the first NGA, but it is optimized with smoothness restraints against a more diverse database.…”

Hydrogen abstraction reactions of OH radicals with CH3CH2CH2Cl and CH3CHClCH3: A mechanistic and kinetic study

“…The model 2 should be recommended for fitting since it gives very small fitting errors for the reactions studied in this work and other references. [50,51] To illustrate the discrepancy caused by fitted models, we plot the rate constants k 1 and k 2 fitted by the model 1 and model 2 in Figures 7a and 7b, respectively. Model 2 clearly provides a better low-temperature asymptotic behavior, which is very important to generate accurate rate constants at any temperature within the range that is used in the fitting and to extrapolate the rate constants beyond the temperature range that used in the fitting.…”

“…Model 1 has been used widely for fitting theoretical rate constants in the literatures. [47][48][49] Recently, Zheng and Truhlar [50] proposed a new model with one more parameter to give small fitting error and have the correct low-temperature asymptotic behavior for activation energy and rate constant, which is called model 2. The model 2 rate constant expression is k ¼ AT n exp[ÀE(TþT 0 )/R(T 2 þT 2 0 )], where A, n, E, and T 0 are fitting parameters and R is the gas constant.…”