DFT study on abstraction reaction mechanism of oh radical with 2-methoxyphenol

Priya, Angappan Mano; Lakshmipathi, Senthilkumar

doi:10.1002/poc.3713

Cited by 20 publications

(14 citation statements)

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“…In addition, differences between density functional theory (DFT) calculations and lab studies have been also observed. For example, the DFT-predicted rate constant of 2-methoxyphenol with OH radicals (12.19 × 10 −11 cm 3 molecule −1 s −1 ) is higher than that (7.53 × 10 −11 cm 3 molecule −1 s −1 ) obtained by a lab study (Coeur-Tourneur et al, 2010a;Priya and Lakshmipathi, 2017). This suggests that it is necessary to determine the rate constants of multifunctional organics through lab experiments.…”

Section: Rate Constantmentioning

confidence: 79%

“…It is well known that a high NO x concentration almost always plays a negative role in NPF and SOA formation be-cause the reaction of NO with RO 2 radicals would result in the formation of more volatile products compared to the reaction of HO 2 with RO 2 radicals (Sarrafzadeh et al, 2016). Previous studies reported that nitro-substituted products were the main products for SOA formed from OH-initiated reactions of phenol precursors, including methoxyphenols, in the presence of NO x (Ahmad et al, 2017;Finewax et al, 2018;Lauraguais et al, 2012Lauraguais et al, , 2014b.…”

Section: Effect Of No 2 On Soa Formationmentioning

confidence: 99%

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Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals

Liu

Chen

et al. 2019

Atmos. Chem. Phys.

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Abstract. Methoxyphenols are an important organic component of wood-burning emissions and considered to be potential precursors of secondary organic aerosol (SOA). In this work, the rate constant and SOA formation potential for the OH-initiated reaction of 4-allyl-2-methoxyphenol (eugenol) were investigated for the first time in an oxidation flow reactor (OFR). The rate constant was 8.01±0.40×10-11 cm3 molecule−1 s−1, determined by the relative rate method. The SOA yield first increased and then decreased as a function of OH exposure and was also dependent on eugenol concentration. The maximum SOA yields (0.11–0.31) obtained at different eugenol concentrations could be expressed well by a one-product model. The carbon oxidation state (OSC) increased linearly and significantly as OH exposure rose, indicating that a high oxidation degree was achieved for SOA. In addition, the presence of SO2 (0–198 ppbv) and NO2 (0–109 ppbv) was conducive to increasing SOA yield, for which the maximum enhancement values were 38.6 % and 19.2 %, respectively. The N∕C ratio (0.032–0.043) indicated that NO2 participated in the OH-initiated reaction, subsequently forming organic nitrates. The results could be helpful for further understanding the SOA formation potential from the atmospheric oxidation of methoxyphenols and the atmospheric aging process of smoke plumes from biomass burning emissions.

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Section: Rate Constantmentioning

confidence: 79%

Section: Effect Of No 2 On Soa Formationmentioning

confidence: 99%

Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals

Liu

Chen

et al. 2019

Atmos. Chem. Phys.

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“…22,30 Then hydroxyl radicals attack hydrogen atoms in the α-methylene (CH 2 ) and also hydroxyl groups (OH) of dextran. 22 These reactive sites can be linked to the methoxy group of the curcumin molecule 31 (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Dextran-immobilized curcumin: An efficient agent against food pathogens and cancer cells

Zare

Sarkati

Tashakkorian

et al. 2019

Journal of Bioactive and Compatible Polymers

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Curcumin–dextran conjugate was synthesized by free radical grafting reaction between curcumin and dextran. The chemical characterization of the conjugate was obtained by Fourier-transform infrared and 1H-NMR (proton nuclear magnetic resonance) spectroscopy analysis, while the functionalization degree was determined by the Folin–Ciocalteu assay, finding a 22.93 mg of curcumin/g of dextran conjugate. Antioxidant activity of curcumin and curcumin–dextran conjugate was investigated employing DPPH• radical method, and IC50 (the half maximal inhibitory concentration) values of curcumin and the curcumin–dextran conjugate (Cur equivalents) were 86.6 ± 0.1 and 17.4 ± 1 µM, respectively. The presence of dextran into the curcumin–dextran conjugate improved radical scavenging activities of the curcumin. In addition, antimicrobial effect of curcumin and curcumin–dextran conjugate was evaluated against gram-positive ( Listeria monocytogenes and Staphylococcus aureus) and gram-negative ( Escherichia coli O157:H7 and Salmonella typhimurium) bacteria. According to our experiments, gram-positive microorganisms are more sensitive to these compounds than gram-negative ones. Curcumin–dextran is a more potent bacteriostat ( S. aureus (minimum inhibitory concentration = 0.008 µg/mL), E. coli O157:H7 (minimum inhibitory concentration = 250 µg/mL), and S. typhimurium (minimum inhibitory concentration = 500 µg/mL)) and also a more potent bacteriosid against S. aureus and S. typhimurium than curcumin. The cytotoxic effects of the curcumin–dextran conjugate toward AGS, MCF-7, and normal fibroblast cell lines were determined at 48 and 72 h using an MTT assay. The results revealed the considerable antiproliferative effects of the curcumin–dextran conjugate in both AGS and MCF-7 cancer cells in comparison with fibroblast cells. This study shows that dextran as a versatile scaffold develops the biological activities of curcumin by covalent grafting and can be regarded in further bioapplications.

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“…In Scheme 2 (pH 4, IPA or NaBC, under air-saturated conditions), additional radicals generated ( • HO2 and CO3 (Priya and Lakshmipathi, 2017;Sun et al, 2019), generating a hydroperoxide (-OCH2OOH) that readily decompose to form -OCH2O • and • OH (Yaremenko et al, 2016). -OCH2O • is finally transformed into -OCHO with the elimination of HO2 in the presence of O2 (Sun et al, 2019).…”

Section: Photo-oxidation Pathways Of Vanillin Via Direct Photosensitization and In The Presence Of Nitratementioning

confidence: 99%

Aqueous SOA formation from the photo-oxidation of vanillin: Direct photosensitized reactions and nitrate-mediated reactions

Mabato

Lyu

et al. 2021

Preprint

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Abstract. Vanillin (VL), a phenolic aromatic carbonyl abundant in biomass burning emissions, forms triplet excited states (3VL*) under simulated sunlight leading to aqueous secondary organic aerosol (aqSOA) formation. This direct photosensitized oxidation of VL was compared with nitrate-mediated VL photo-oxidation under atmospherically relevant cloud and fog conditions, through examining the VL decay kinetics, product compositions, and light absorbance changes. The majority of the most abundant products from both VL photo-oxidation pathways were potential Brown carbon (BrC) chromophores. In addition, both pathways generated oligomers, functionalized monomers, and oxygenated ring-opening products, but nitrate promoted functionalization and nitration, which can be ascribed to its photolysis products (•OH, •NO2, and N(III), NO2- or HONO). Moreover, a potential imidazole derivative observed from nitrate-mediated VL photo-oxidation suggested that ammonium may be involved in the reactions. The effects of secondary oxidants from 3VL*, pH, the presence of volatile organic compounds (VOCs) and inorganic anions, and reactants concentration and molar ratios on VL photo-oxidation were also explored. Our findings show that the secondary oxidants (1O2, O2•-/•HO2, •OH) from the reactions of 3VL* and O2 play an essential role in VL photo-oxidation. Enhanced oligomer formation was noted at pH < 4 and in the presence of VOCs and inorganic anions, probably due to additional generation of radicals (•HO2 and CO3•-). Also, functionalization was dominant at low VL concentration, whereas oligomerization was favored at high VL concentration. Furthermore, guaiacol oxidation by photosensitized reactions of VL was observed to be more efficient relative to nitrate-mediated photo-oxidation. Lastly, potential VL photo-oxidation pathways under different reaction conditions were proposed. This study indicates that the direct photosensitized oxidation of VL, which nitrate photolysis products can further enhance, may be an important aqSOA source in areas influenced by biomass burning emissions.

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DFT study on abstraction reaction mechanism of oh radical with 2-methoxyphenol

Cited by 20 publications

References 74 publications

Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals

Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals

Dextran-immobilized curcumin: An efficient agent against food pathogens and cancer cells

Aqueous SOA formation from the photo-oxidation of vanillin: Direct photosensitized reactions and nitrate-mediated reactions

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