Thermodynamic and kinetic study of ibuprofen with hydroxyl radical: A density functional theory approach

Xiao, Ruiyang; Noerpel, Matt; Luk, Hoi Ling; Wei, Zongsu; Spinney, Richard

doi:10.1002/qua.24518

Cited by 100 publications

(37 citation statements)

References 55 publications

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“…The partition functions for the respective TS and reactants at 298 K are obtained from the vibrational frequencies calculation made at MPWB1K/6-31+G(d,p) level. The tunneling correction Γ(T) was estimated by using the Eckart's unsymmetric barrier method [48,49]. In this method, the reaction path through TS is fitted first in a model potential function…”

Section: Resultsmentioning

confidence: 99%

Theoretical investigation on mechanism and kinetics of the Cl-initiated hydrogen abstraction reactions of ethyl trifluoroacetate at 298 K

2014

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Theoretical investigations were carried out on the gas-phase reactions of CF3C(O)OCH2CH3, ethyl trifluoroacetate (ETFA) with Cl atoms by means of modern density functional theory methods. The optimized geometries, frequencies and minimum energy path were obtained with the hybrid density functional model MPWB1K using the 6-31+G(d,p) basis set. The single point energy calculations were refined further using the G2(MP2) method. Two conformers relatively close in energy were identified for ETFA; both are likely to be important in the temperature range of our study. The existence of transition states on the corresponding potential energy surface was ascertained by performing intrinsic reaction coordinate calculations. The rate constant at 298 K calculated theoretically using canonical transition state theory was found to be in good agreement with experimentally measured values. Our calculations suggest that H abstraction from the -CH2 group is kinetically and thermodynamically more favorable than abstraction from the -CH3 group. The atmospheric lifetime of ETFA with Cl atoms was determined to be 1.98 years. To the best of our knowledge, this work represents the first determination of the rate coefficients for the gas-phase reaction of chlorine atoms in ETFA.

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Section: Resultsmentioning

confidence: 99%

Theoretical investigation on mechanism and kinetics of the Cl-initiated hydrogen abstraction reactions of ethyl trifluoroacetate at 298 K

2014

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“…B3LYP contains less empirical parameters than HCTH/407, thereby it seems to be more universal. B3LYP has been successfully used to model both thermodynamic and kinetic properties of free radicals [18,32,33]. Thus, we used B3LYP in the majority of our calculations.…”

Section: Discussionmentioning

confidence: 99%

“…The rate of reaction (M -1 s -1 ) between antioxidant and radical was calculated as in [32,46] using conventional TS theory: where I is the reaction pathway degeneracy (equal to 1 for the all compounds), k B is Boltzmann's constant, h is Planck's constant, 24.3 is a multiplier used to convert the units from 1 atmosphere standard state to 1 M standard state, and A(T) is a temperature-dependent factor which corresponds to quantum mechanical tunneling, approximated by the Wigner method [82]: where ν i is the imaginary frequency (cm -1 ) whose vibrational motion determines the direction of the reaction.…”

Section: Methodsmentioning

confidence: 99%

“…In this study, the redox properties of kynurenines and several synthetic phenolic antioxidants were investigated computationally using density functional theory (DFT) approach. The validity of B3LYP methods to model phenolic antioxidants and free radical reactions has already been proved [18,32]. The methodology was similar to that of [18,33]: the energies of frontier highest occupied and lowest unoccupied molecular orbitals (E HOMO , E LUMO ), phenolic O-H bond dissociation enthalpy (BDE), and ionization potential (IP) were calculated and compared for structures fully optimized in the gas phase.…”

Section: Introductionmentioning

confidence: 99%

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Antioxidant Properties of Kynurenines: Density Functional Theory Calculations

et al. 2016

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Kynurenines, the main products of tryptophan catabolism, possess both prooxidant and anioxidant effects. Having multiple neuroactive properties, kynurenines are implicated in the development of neurological and cognitive disorders, such as Alzheimer's, Parkinson's, and Huntington's diseases. Autoxidation of 3-hydroxykynurenine (3HOK) and its derivatives, 3-hydroxyanthranilic acid (3HAA) and xanthommatin (XAN), leads to the hyperproduction of reactive oxygen species (ROS) which damage cell structures. At the same time, 3HOK and 3HAA have been shown to be powerful ROS scavengers. Their ability to quench free radicals is believed to result from the presence of the aromatic hydroxyl group which is able to easily abstract an electron and H-atom. In this study, the redox properties for kynurenines and several natural and synthetic antioxidants have been calculated at different levels of density functional theory in the gas phase and water solution. Hydroxyl bond dissociation enthalpy (BDE) and ionization potential (IP) for 3HOK and 3HAA appear to be lower than for xanthurenic acid (XAA), several phenolic antioxidants, and ascorbic acid. BDE and IP for the compounds with aromatic hydroxyl group are lower than for their precursors without hydroxyl group. The reaction rate for H donation to *O-atom of phenoxyl radical (Ph-O*) and methyl peroxy radical (Met-OO*) decreases in the following rankings: 3HOK ~ 3HAA > XAAOXO > XAAENOL. The enthalpy absolute value for Met-OO* addition to the aromatic ring of the antioxidant radical increases in the following rankings: 3HAA* < 3HOK* < XAAOXO* < XAAENOL*. Thus, the high free radical scavenging activity of 3HAA and 3HOK can be explained by the easiness of H-atom abstraction and transfer to O-atom of the free radical, rather than by Met-OO* addition to the kynurenine radical.

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“…In alkaline conditions, IBP anions are abundant in aqueous environments. 26 Then the reaction of IBP anion with OH radical is investigated.…”

Section: Reaction Of Ibp Anion With Oh Radicalmentioning

confidence: 99%

OH-initiated AOPs degradation mechanism of ibuprofen in aqueous environments

et al. 2014

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As a common pharmaceutical and personal care product, ibuprofen (IBP) is regarded as an important pollutant in aqueous environments. In this paper, the OH-initiated advanced oxidation processes (AOPs) degradation mechanism and its subsequent reaction mechanism with IBP were studied at the M06-2x/6-311++G(2d, p)//M06-2x/6-31+G(d,p) level. The frontier electron density and bond dissociation energy were analyzed. In addition, profiles of the potential energy surface were constructed, and all the possible pathways were discussed. H-atom abstraction is the most important mechanism. The dominant products were IBAP, 2-[4-(1-hydroxyisobutyl)phenyl]propionic acid, and 1-(4-isobutylphenyl)-1-ethanol, which is in good agreement with the experimental results.

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Thermodynamic and kinetic study of ibuprofen with hydroxyl radical: A density functional theory approach

Cited by 100 publications

References 55 publications

Theoretical investigation on mechanism and kinetics of the Cl-initiated hydrogen abstraction reactions of ethyl trifluoroacetate at 298 K

Theoretical investigation on mechanism and kinetics of the Cl-initiated hydrogen abstraction reactions of ethyl trifluoroacetate at 298 K

Antioxidant Properties of Kynurenines: Density Functional Theory Calculations

OH-initiated AOPs degradation mechanism of ibuprofen in aqueous environments

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