Theoretical Chemical Kinetic Study of the H-Atom Abstraction Reactions from Aldehydes and Acids by Ḣ Atoms and ȮH, HȮ₂, and ĊH₃ Radicals

Abstract

We have performed a systematic, theoretical chemical kinetic investigation of H atom abstraction by Ḣ atoms and ȮH, HȮ2, and ĊH3 radicals from aldehydes (methanal, ethanal, propanal, and isobutanal) and acids (methanoic acid, ethanoic acid, propanoic acid, and isobutanoic acid). The geometry optimizations and frequencies of all of the species in the reaction mechanisms of the title reactions were calculated using the MP2 method and the 6-311G(d,p) basis set. The one-dimensional hindered rotor treatment for reactants and transition states and the intrinsic reaction coordinate calculations were also determined at the MP2/6-311G(d,p) level of theory. For the reactions of methanal and methanoic acid with Ḣ atoms and ȮH, HȮ2, and ĊH3 radicals, the calculated relative electronic energies were obtained with the CCSD(T)/cc-pVXZ (where X = D, T, and Q) method and were extrapolated to the complete basis set limit. The electronic energies obtained with the CCSD(T)/cc-pVTZ method were benchmarked against the CCSD(T)/CBS energies and were found to be within 1 kcal mol(-1) of one another. Thus, the energies calculated using the less expensive CCSD(T)/cc-pVTZ method were used in all of the reaction mechanisms and in calculating our high-pressure limit rate constants for the title reactions. Rate constants were calculated using conventional transition state theory with an asymmetric Eckart tunneling correction, as implemented in Variflex. Herein, we report the individual and average rate constants, on a per H atom basis, and total rate constants in the temperature range 500-2000 K. We have compared some of our rate constant results to available experimental and theoretical data, and our results are generally in good agreement.

A comprehensive experimental and modeling study of isobutene oxidation

“…H-atom abstraction from methacrolein (iC 3 H 5 CHO) to form iC 3 H 5 ĊO radical and H 2 O promotes reactivity at intermediate temperatures (Figure 7, Figure 8, and Figure 25). The rate constant for this reaction channel is taken from the ab initio calculations of Mendes et al [68]. H-atom abstractions from metharolein by HȮ 2 and ĊH 3 radicals and Ḣ atoms have also been included from calculations by Mendes et al [68].…”

“…The rate constant for this reaction channel is taken from the ab initio calculations of Mendes et al [68]. H-atom abstractions from metharolein by HȮ 2 and ĊH 3 radicals and Ḣ atoms have also been included from calculations by Mendes et al [68]. is favored over the higher barrier isomerization reaction processes.…”

Understanding the reactivity of unsaturated alcohols: Experimental and kinetic modeling study of the pyrolysis and oxidation of 3-methyl-2-butenol and 3-methyl-3-butenol

“…for hydrogen abstraction from the carbonyl group in aldehydes, reaction rate coefficients were taken from literature, e.g. Mendes et al [60].…”

Unrestricted Floating Orbitals for the Investigation of Open Shell Systems

“…Furthermore, reactions with other small molecules like carbon monoxide (Das & Lee, 2014), the recombination reaction with OH radicals (Oliveira & Bauerfeldt, 2012), and even the role in methanol synthesis (Zakharov, Ijagbuji, Tselishtev, Loriya, & Fedotov, 2015) have been studied recently. Due to its high reactivity, the methyl radical is involved in reactions which comprise the abstraction of a hydrogen atom so that many recent studies deal with the kinetic properties of these reactions (Mendes, Zhou, & Curran, 2014), (Saheb, 2015), (Tan, Yang, Krauter, Ju, & Carter, 2015). Firstly, our own FORTRAN 2003 code FORPLEASURE (Brüssel, Perlt, & Kirchner, 2012-2016 Table 1, where also the applied basis sets are given.…”