Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Abstract

Hydrogen atom abstraction from propargyl C-H sites of alkynes plays a critical role in determining the reactivity of alkyne molecules and understanding the formation of soot precursors. This work reports a systematic theoretical study on the reaction mechanisms and rate constants for hydrogen abstraction reactions by hydrogen and hydroxy radicals from a series of alkyne molecules with different structural propargyl C-H atoms. Geometry optimizations and frequency calculations for all species are performed at M06-2X/cc-pVTZ level of theory and the hindered internal rotations are also treated at this level. The high-level W1BD and CCSD(T)/CBS theoretical calculations are used as a benchmark for a series of DFT calculations toward the selection of accurate DFT functionals for large reaction systems in this work. Based on the quantum chemistry calculations, rate constants are computed using the canonical transition state theory with tunneling correction and the treatment of internal rotations. The effects of the structure and reaction site on the energy barriers and rate constants are examined systematically. To the best of our knowledge, this work provides the first systematic study for one of the key initiation abstraction reactions for compounds containing propargyl hydrogen atoms.

A Statistically Supported Antioxidant Activity DFT Benchmark—The Effects of Hartree–Fock Exchange and Basis Set Selection on Accuracy and Resources Uptake

“…One would wonder why such unusual basis sets as Ahlrich’s or Dunning’s, or methods such as TPSSh or WB97, were chosen when Pople’s [ 53 , 54 , 55 ], particularly when combined with Minnesota’s functionals [ 26 , 56 , 57 , 58 , 59 ], are leading the way? At the time of writing this paper, we were barely able to find articles that used def2– [ 60 ] or (aug–)cc–pVXZ [ 61 , 62 , 63 ] basis sets in their studies on antioxidative activity. A similar situation occurred in the case of functionals where, with a few exceptions, the bulk of papers used B3LYP and Minnesota functionals.…”

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

“…Thematic Area 2 includes 22 articles, namely [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ], the typification of which is shown in Table 3 . With some degree of conventionality, it is possible to subdivide the articles published here into two main groups, namely, articles devoted to the study of the kinetics of processes in which any chemical transformations are decisive, and articles devoted to the study of the kinetics of processes in which chemical transformations are either not decisive or absent altogether.…”

“…This direction is represented by 39 articles [ 28 , 35 , 129 , 134 , 136 , 190 , 191 , 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 , 200 , 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 , 209 , 210 , 211 , 212 , 213 , 214 , 215 , 216 , 217 , 218 , 219 , 220 , 221 , 222 , 223 ]. Their distribution, according to the above types, is presented in Table 7 .…”

“…In this research, the given reaction between cyclopentadiene and methyl acrylate was computationally investigated in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM] [PF 6 ], as a basis for the validation of the OPLS-VSIL to properly reproduce a reaction medium environment. The articles of group ( c ) include publications [ 28 , 129 , 136 , 193 , 195 , 199 , 200 , 202 , 208 , 209 , 212 , 213 , 215 , 220 ]: in most of them [ 129 , 136 , 195 , 199 , 200 , 202 , 208 , 209 , 212 , 215 ], the objects of quantum chemical calculations were the chelate and macrocyclic coordination compounds of various s -, p -, d -, and f -elements. The most significant of them seems to be publication [ 136 ], devoted to Pu(IV) and Pu(VI) complexes with tridentate (NNN)-donor-atomic ligands, in particular, di(pyridyl-2)amine, 1,3-diamino-2-azapropane, and 2,6-di(pyridyl-2) pyridine, the results of which can be very useful in the development of new extractants and organic sensors of plutonium.…”

“…In [ 129 , 213 ], quantum–chemical methods used for calculating DFT OPBE/TZVP and DFT B3PW91/TZVP were used to substantiate the fundamental possibility of the existence of complexes of iron, cobalt, and nickel with porphyrazine, its derivatives, and oxo ligands in oxidation state VI that is unusual for these elements. Inorganic compounds that are not coordination compounds were considered only in [ 28 , 193 , 215 , 220 ]. It should be noted that the only review in this thematic area is [ 220 ], devoted specifically to the quantum–chemical calculations of chemical compounds, namely, the structures of higher fullerenes, in which, among other things, a formalization of the substructure approach to assessing the stability of higher fullerenes is proposed, which is based on a detailed analysis of the main structural features of fullerene molecules.…”