A DFT mechanistic, thermodynamic and kinetic study on the reaction of 1, 3, 5-trihydroxybenzene and 2, 4, 6-trihydroxyacetophenone with ^•OOH in different media

Abstract

A theoretical investigation on the reactions of 1, 3, 5-trihydroxybenzene (PG) and 2, 4, 6-trihydroxyacetophenone (ACPG) with •OOH has been performed with the aim of elucidating the peroxyl radical scavenging properties of PG and its acylated derivative. The study has considered the hydrogen atom transfer (HAT), the single electron transfer-proton transfer and the sequential proton loss-electron transfer mechanisms and determined the geometric, energetic and electronic properties of the reaction species as well as the kinetic parameters for the HAT mechanism. DFT/M06-2X, DFT/MPW1K and DFT/BHHLYP calculation methods have been utilized in combination with the 6-311++G(3df, 2p) basis set. The DFT methods were benchmarked using the CBS-QB3 method. Thermodynamic parameters such as bond dissociation enthalpy (BDE) and ionization energy suggest that the thermodynamically preferred mechanism is the HAT mechanism. The geometric, electronic and energetic parameters suggest that the preferred site for the abstraction of the free phenolic H atom in ACPG is the ortho position. Spin density and branching ratio values indicate that the most stable and preferable product formed is for the reaction of ACPG [Formula: see text] •OOH at the ortho position. The estimated rate constants obtained indicate that the reaction of ACPG [Formula: see text] •OOH is kinetically preferred to the reaction of PG [Formula: see text] •OOH, which is in agreement with experimental findings.

Reactivity of Isocyanate Radical with Formic Acid in the Tropospheric and Outer Space Regions: A DFT and MP2 Investigation in Gaseous Phase

“…The transition state structures were obtained by scanning the selected bond in relation to the hydrogen atom to be transferred from HCOOH to NCO radical, as has been developed in previous works. [49][50][51][52] Intrinsic reaction coordinate (IRC) calculations [53] were also performed in order to establish that the identified transition states joined the reactant species and product species smoothly. Vibrational frequency calculations were performed on the optimised species, by using the same basis set as the basis set that was used to optimise the structure.…”

DFT Study of Complexation Reactions Involving Dicarboxylic Acids: Hydrogen Bonds, Influence of Solvent Nature

“…The dimerization energy can be another parameter that makes it possible to judge the stability of hydrogen-bonded complexes [17][18][19]. Table 2 illustrates the energies of individual molecules (Еacid) and the energies of dimers (Еdimer), which were calculated considering the BSSE (Basis Set Superposition Error) correction for the imperfection of the basis set.…”

Antioxidant and anticancer properties of plant‐based bioactive flavonoids cardamonin and alpinetin: A theoretical insight from •OOH antiradical and Cu (II) chelation mechanisms

“…Based on previous reaction of polyphenol derivatives with • OOH have directed that the efficiency of the antioxidant molecules to scavenge peroxyl radical is better observed in non-polar medium [28,34,35] than in polar medium. For this reason, the reactions involving • OOH that are investigated in this work are carried out in the presence of the benzene solvent, which serves as a representative medium for the non-polar lipid bilayer medium present within biological systems.…”