Prenol as a Next-Generation Biofuel or Additive: A Comprehension of the Hydrogen Abstraction Reactions by a H Atom

Abstract

Thermal rate coefficients for the hydrogen abstraction reactions of prenol (3-methyl-2-butenol) by a hydrogen atom were calculated with the multipath canonical variational theory with small-curvature tunneling (MP-CVT/SCT). The conformational search was performed with a dual-level approach, and the multistructural torsional anharmonicity effects were corrected through the rovibrational partition function calculated with the multistructural method based on a coupled torsional potential (MS-T­(C)). This methodology allows us to estimate the thermal rate constants in the temperature range of 200–2500 K and fit them into two analytical expressions. Differences between the number of conformations on the torsional potential energy surfaces for prenol and the transition state decrease the thermal rate constants for the H-abstraction at the α carbon. An opposite behavior was detected for the abstractions on the δ site. The product branching ratios were calculated using single-structure and multipath approaches. The product distributions from the former are shown to be inadequate for studying the mechanism under combustion conditions. The values estimated from MP-CVT/SCT rate coefficients indicated that the radicals from (R α) and (R δ)/(R δ′) are formed in considerable amounts. These species are fundamental in comprehending the inhibition and promotion of the autoignition phenomena.

The Interplay between the Temperature and Pressure on the Reaction Pathways of the Prenol Oxidation by Hydroxyl Radicals

“…Figure S1 of the Supporting Information depicts the dihedral angles used in this search. In concordance with our previous study, [9] seven conformers (including the enantiomers) were found in the for the prenol, with the A + G − as the most stable structure. For the HA from the OH group of prenol (TS abs‐OH ), 14 conformations within 1.35 kcal/mol were located.…”

“…Although the previous study has been dedicated to the production [3–6] and the oxidation, [7–9] its detailed combustion mechanism, the preferred radical or adduct formation, and temperature and pressure dependence still need to be fully understood. Combining experimental and theoretical results, Mohamed et al [10] .…”

“…Although the previous study has been dedicated to the production [3][4][5][6] and the oxidation, [7][8][9] its detailed combustion mechanism, the preferred radical or adduct formation, and temperature and pressure dependence still need to be fully understood. Combining experimental and theoretical results, Mohamed et al [10] investigated the kinetics of the reactions of prenol and isoprenol with OH radicals between 900 and 1290 K and 1-5 atm using shock tube and OH laser diagnostic and transition state theory.…”

Insights into the role of the H-abstraction reaction kinetics of amines in understanding their degeneration fates under atmospheric and combustion conditions

“…Compared with the MS-CVT/SCT method, the MP-CVT/SCT method gives a more realistic description of the process of chemical reactions and gives a more accurate rate constant, as examined in the literature studies. 227–231…”

“…where F SS-T TS,p is the single-structural torsional anharmonicity factor of the TS for reaction path p and P k SCT p G CVT p F SS-T TS;p can be integrated into a reaction correction factor considering the tunneling, recrossing, and torsional anharmonicity of reaction path p. Compared with the MS-CVT/SCT method, the MP-CVT/ SCT method gives a more realistic description of the process of chemical reactions and gives a more accurate rate constant, as examined in the literature studies. [227][228][229][230][231] During the MS-T factor calculations, all the torsions in the molecule should be simultaneously rotated by 01, 1201, and À1201, to generate the initial possible conformers, which are further optimized using a selected density-functional-theory (DFT) method. For a large flexible molecule with the number of torsions 46, however, it is quite unaffordable and challenging to optimize such numerous initial conformers.…”