Formation of nitroxide radicals from secondary amines and peracids: A peroxyl radical oxidation pathway derived from electron spin resonance detection and density functional theory calculation

Shi, Hongchang; Li, Yong

doi:10.1016/j.molcata.2007.02.012

Cited by 18 publications

(17 citation statements)

References 37 publications

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“…42 The density functional theory calculation by Shi et al highlighted the similarity of aroyloxyl radical and CH 3 C(O)O • in terms of reactivity, but aromatic ring of aroyloxyl radical may increase its stability. 51 43 In their experiments, they observed the branching ratio between stable CH 3 C(O)O • and decarboxylated products to be about 1:9, and the stable CH 3 C(O)O • had a lifetime of at least 10 μs or longer. 43 On the basis of the lower limit of lifetime of CH 3 C(O)O • by Lu and Continetti, 43 we could calculate the decarboxylation rate to be equal or less than 2. oxygenated aqueous methane solution and concluded that 56% of • OOCH 3 self-decayed following the Russell reaction (R48a), with an overall bimolecular decay rate of k = 5.0 × 10 8 M −1 s −1 for • OOCH 3 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…They concluded that the reaction rate for H-abstraction and π-bond addition by aroyloxyl radical is often within the range of 10 5 –10 7 M –1 s –1 and 10 6 –10 9 M –1 s –1 , respectively . The density functional theory calculation by Shi et al highlighted the similarity of aroyloxyl radical and CH 3 C(O)O • in terms of reactivity, but aromatic ring of aroyloxyl radical may increase its stability . However, CH 3 C(O)O • can undergo unimolecular decay commonly referred as decarboxylation yielding CO 2 and • CH 3 (R46).…”

Section: Resultsmentioning

confidence: 99%

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Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process

Zhang

Huang

2020

Environ. Sci. Technol.

192

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Peracetic acid combined with UV (i.e., UV/PAA) has emerged as a novel advanced oxidation process (AOP) for water disinfection and micropollutant degradation, but kinetic modeling for this AOP was lacking. In this study, a comprehensive model was developed to elucidate the reaction mechanisms and simulate reaction kinetics of UV/PAA process. By combining radical scavenging experiments and kinetic modeling, accurate quantum yield of PAA under UV254 (Φ = 0.88 ± 0.04 mol-Einstein–1) was determined via simultaneously quenching •OH and CH3C(O)O• with 2,4-hexadiene. The comparison between experimental observations and model predictions over a wide range of conditions allowed estimation of the rate constants of PAA with •OH (k •OH/PAA = 1.3 ± 0.2 × 109 M–1 s–1) and HO2 • (k HO2 •/PAA ≤ 5 × 102 M–1 s–1) with good accuracy. With derived Φ, k •OH/PAA and k HO2 •/PAA, the kinetic model accurately predicts PAA decay under UV254 photolysis across varying PAA and H2O2 concentrations and water pH (5.8–7.2). Meanwhile, the model reveals that UV/PAA generates a lower •OH concentration than UV/H2O2 at equivalent oxidant concentrations, with CH3C(O)OO• as the most abundant carbon-centered radical. This study significantly improves the knowledge of reactive species generation and reaction kinetics and mechanisms under UV/PAA, and provides a useful kinetic model for this AOP in water treatment.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process

Zhang

Huang

2020

Environ. Sci. Technol.

192

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“…The (waste)water disinfection and oxidation of aqueous (micro)pollutants by peracids are based on the formation of highly oxidative radical species, such as the hydroxyl radical (HO•), the superoxide anion (•O 2 -), the hydroperoxyl radical (HO 2 •), acyl, and peracyl radicals [78]. These radicals are together referred to as reactive oxygen species (ROS).…”

Section: Reactions In Aqueous Media: Disinfection and Oxidation Mechamentioning

confidence: 99%

“…All of the generated radicals contribute to the oxidation reactions, but HO·, peracetyl radical (CH 3 COO·), and to a lesser extent the methyl radical (·CH 3 ) have been suggested to be the most important [80,85]. However, ·CH 3 is of limited availability due to the lower reaction rate constant compared to HO· and the reaction with oxygen (Reaction 7) [78,80]. On the other ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 10 hand, organic radicals have longer half-lives than HO·, and some have argued that they are therefore more effective in antimicrobial action [86,87].…”

Section: Reactions In Aqueous Media: Disinfection and Oxidation Mechamentioning

confidence: 99%

Peracids in water treatment: A critical review

Luukkonen

Pehkonen

2016

Critical Reviews in Environmental Science and Technology

271

122

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Peracids have gained interest in the water treatment over the last few decades. Peracetic acid (CH 3 CO 3 H) has already become an accepted alternative disinfectant in wastewater disinfection whereas performic acid (CHO 3 H) has been studied much less, although it is also already commercially available. Peracids have also been tested for drinking water disinfection, oxidation of aqueous (micro)pollutants, sludge treatment and ballast water treatment, to name just a few examples. The purpose of this review paper is to represent comprehensive up-to-date information about the water treatment applications, aqueous reaction mechanisms, and disinfection byproduct formation of peracids, namely performic, peracetic and perpropionic acids. and PFA have several of the qualities of an ideal disinfectant: toxicity to microorganisms, but not to higher forms of life; effectivity at ambient temperatures; stability and long shelf-life; low corrosivity; deodorizing ability; widespread availability and reasonable cost [12].PAA and PFA are colorless liquids with characteristic pungent odors. Both are thermodynamically unstable and can decompose spontaneously or explode when highly concentrated, heated, under mechanical stress or exposed to catalytic effects of impurities [1,13,14]. The recommended storage temperatures are below 30 and 20°C for PAA and PFA, respectively [6,14]. Longer carbon chain length increases stability, and thus PAA is more stable than PFA [1]. However, the O-O bond dissociation energy of PFA and PAA has been calculated to be similar: 48 kcal/mol [15]. Percarboxylic acids have typically pK a values 3-4 units higher than the parent carboxylic acids [1]. Nonetheless, PFA and PAA are corrosive [16]. ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 3Exposure to PAA and PFA causes irritation and possibly permanent damage to the skin (cutaneous emphysema), eyes and the respiratory system. In the skin contact, 0.2% is proposed as the no-observed-effect concentration (NOEC) for short and medium length exposure [17].When inhaled, airborne concentrations less than 0.16-0.17 ppm (0.50-0.52 mg/m 3 ) are considered to cause no irritation [17,18]. However, higher concentrations are harmful and a case study suggested that PAA could cause occupational asthma [19].The largest users of PAA on a global scale (estimated in 2013) are shown in Fig. 1. Similar numbers are not available for PFA, but it is probably used at significantly lower quantities.The largest user, the food industry, applies PAA as a disinfectant in fresh produce washing water, clean-in-place (CIP) processes, on food processing equipment, and in pasteurizers, to name just a few examples [21,22]. PFA is also a suitable disinfectant in low-temperature refrigerated food processing and storage rooms [23]. In healthcare, PAA is used for instance in Recently, methods to determine the residual PAA from wastewater were compared: the spectrophotometric method using DPD and catalase was recommended for 0.1-0.5 mg/L PAA concentrations and the cerimetric/iodometric titration...

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“…Nitroxide radicals, especially (2,2,6,6-tetramethylpiperidin-1-yl)oxyl [14,15,16], are stable, persistent free radicals [17]. Tetramethylpyrrolidine-N-oxide (TEMPO) can function as a single electron transfer oxidant [18,19].…”

Section: Resultsmentioning

confidence: 99%

The Adductomics of Isolevuglandins: Oxidation of IsoLG Pyrrole Intermediates Generates Pyrrole–Pyrrole Crosslinks and Lactams

Jang

Zhang

et al. 2019

High-Throughput

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Isoprostane endoperoxides generated by free radical-induced oxidation of arachidonates, and prostaglandin endoperoxides generated through enzymatic cyclooxygenation of arachidonate, rearrange nonenzymatically to isoprostanes and a family of stereo and structurally isomeric γ-ketoaldehyde seco-isoprostanes, collectively known as isolevuglandins (isoLGs). IsoLGs are stealthy toxins, and free isoLGs are not detected in vivo. Rather, covalent adducts are found to incorporate lysyl ε-amino residues of proteins or ethanolamino residues of phospholipids. In vitro studies have revealed that adduction occurs within seconds and is uniquely prone to cause protein–protein crosslinks. IsoLGs accelerate the formation of the type of amyloid beta oligomers that have been associated with neurotoxicity. Under air, isoLG-derived pyrroles generated initially are readily oxidized to lactams and undergo rapid oxidative coupling to pyrrole–pyrrole crosslinked dimers, and to more highly oxygenated derivatives of those dimers. We have now found that pure isoLG-derived pyrroles, which can be generated under anoxic conditions, do not readily undergo oxidative coupling. Rather, dimer formation only occurs after an induction period by an autocatalytic oxidative coupling. The stable free-radical TEMPO abolishes the induction period, catalyzing rapid oxidative coupling. The amine N-oxide TMAO is similarly effective in catalyzing the oxidative coupling of isoLG pyrroles. N-acetylcysteine abolishes the generation of pyrrole–pyrrole crosslinks. Instead pyrrole-cysteine adducts are produced. Two unified single-electron transfer mechanisms are proposed for crosslink and pyrrole-cysteine adduct formation from isoLG-pyrroles, as well as for their oxidation to lactams and hydroxylactams.

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Formation of nitroxide radicals from secondary amines and peracids: A peroxyl radical oxidation pathway derived from electron spin resonance detection and density functional theory calculation

Cited by 18 publications

References 37 publications

Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process

Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process

Peracids in water treatment: A critical review

The Adductomics of Isolevuglandins: Oxidation of IsoLG Pyrrole Intermediates Generates Pyrrole–Pyrrole Crosslinks and Lactams

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