The Reactivity of Aromatic Compounds toward Hydroxyl Radicals

Anbar, M.; Meyerstein, Dan; Neta, P.

doi:10.1021/j100880a034

Cited by 222 publications

(107 citation statements)

References 6 publications

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“…As proposed in Slade and Knopf (2014) and observed for other nitro-phenolic species, OH oxidation of MNC can favor removal of the -nitro functionality by electrophilic substitution of OH (Slade and Knopf, 2013;Di Paola et al, 2003;Chen et al, 2007). OH substitution at the -methyl position and addition to the double bonds is also possible (Anbar et al, 1966). OH addition to the -nitro or -methyl functionality would increase O : C to ∼ 0.43 or ∼ 0.5, respectively.…”

Section: Ccn Activity Of Bba Surrogate Particlesmentioning

confidence: 74%

Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

et al. 2015

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Abstract. Multiphase OH and O 3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O 3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particles exposed to OH and O 3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O 3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O 3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ∼ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNCcoated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by watersoluble organic carbon (WSOC) or inorganic ions, chemical aging has no significant impact on OA hygroscopicity. The organic compounds exhibiting low solubility behave as if they are infinitely soluble when mixed with a sufficient number of water-soluble compounds. At and beyond this point, the particles' CCN activity is governed entirely by the watersoluble fraction and is not influenced by the oxidized organic fraction. Our results have important implications for heterogeneous oxidation and its impact on cloud formation given that atmospheric aerosol is a complex mixture of organic and inorganic compounds exhibiting a wide range of solubilities.

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Section: Ccn Activity Of Bba Surrogate Particlesmentioning

confidence: 74%

Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

et al. 2015

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“…If the oxidizing species were an iron-0x0 complex, the oxidation product of H,S would be H,SO,, not S8. (3) The hydroxylation products of benzoic acid are the same as those produced by the 'OH radical generated without a chelating agent present (18,19). (4) The addition of free radical scavengers (Na2S20,, benzoic acid, etc.)…”

Section: Esr Measurementsmentioning

confidence: 99%

Studies on the mechanism of chelate degradation in iron-based, liquid redox H₂S removal processes

Chen¹,

Martell²,

McManus³

1995

Can. J. Chem.

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Available data on the oxidation of nitrilotriacetic acid (NTA), ethylenedinitrilotetraacetic acid (EDTA), N-hydroxyethylethylenediaminetriacetic acid (HEDTA), and other aminopolycarboxylate chelating agents are reviewed and the intermediates and products of the oxidative degradation of each chelating agent are described and compared. The oxidation of these chelating agents occurs during the reoxidation of the ferrous chelate to the femc chelate, during which a Fenton type side reaction occurs in which hydrogen peroxide is formed and which in turn generates the hydroxyl radical by reaction with ferrous ion. The site of oxidative attack by the hydroxyl radical on these ligands seems to be the -CH,-groups a to the carboxylate groups, as well as the -CH,-groups in the ethylene bridges between the nitrogens. The evidence for the implication of the hydroxyl radical as the active oxidant is discussed, and the use of phenyl-tert-butylnitrone (PBN) as the trapping agent for the hydroxyl radical is described. The use of chelating agents as ~e~+ / F e ' + redox catalysts for the oxidation of H,S to sulfur that are less reactive toward the hydroxyl radical is recommended.

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“…The choice of this system is appropriate from the perspective that considerable, recent experimental information is available concerning the reactions of hydroxyl radical with pyridine, substituted pyridines, and related benzene systems (14)(15)(16)(17)(18)(19). Investigations have also been undertaken into the effects associated with protonation and metal ion complexation (16,17,(20)(21)(22).…”

Section: Introductionmentioning

confidence: 99%

Abinitio SCF MO calculations on the reactions of OH radical with pyridine and pyridinium ion

Anthony¹,

Waltz²,

Mezey³

1982

Can. J. Chem.

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Relative energies of various products formed in the reaction of pyridine and pyridinium ion with the hydroxyl radical are calculated using non-empirical SCF MO techniques. The favourable electron delocalization in the meta-products, rather than the electrophilic character of the OH radical is the determining factor of relative stabilities. Calculated energy barriers along approximate reaction paths correlate with the available experimental information.

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The Reactivity of Aromatic Compounds toward Hydroxyl Radicals

Cited by 222 publications

References 6 publications

Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

Studies on the mechanism of chelate degradation in iron-based, liquid redox H₂S removal processes

Abinitio SCF MO calculations on the reactions of OH radical with pyridine and pyridinium ion

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The Reactivity of Aromatic Compounds toward Hydroxyl Radicals

Cited by 222 publications

References 6 publications

Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

Studies on the mechanism of chelate degradation in iron-based, liquid redox H2S removal processes

Abinitio SCF MO calculations on the reactions of OH radical with pyridine and pyridinium ion

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Studies on the mechanism of chelate degradation in iron-based, liquid redox H₂S removal processes