Comments on the Mechanism of the “Fenton-Like” Reaction

Goldstein, Sara; Meyerstein, Dan

doi:10.1021/ar9800789

Cited by 204 publications

(131 citation statements)

References 21 publications

(64 reference statements)

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“…It is also known that the Fenton system can be broadened to other lower valence transition metals which have one-electron redox couples [e.g., Co(I)/Co(II), Cu(I)/Cu(II), Mn(II)/Mn(III), Ti(III)/Ti(IV)] and organic hydroperoxides (e.g., alkyl hydroperoxides, ROOH) or hypohalous acids (e.g., HOCl). More information about Fenton and Fenton-like systems can be found in Haber and Weiss (1934), Barb et al (1951a,b), Walling (1975), Edwards and Curci (1992), Sychev and Isaak (1995), Goldstein andMeyerstein (1999) andDe Laat (2004) and references cited therein.…”

Section: Acid Hydrogen Peroxidementioning

confidence: 99%

Energy efficient refining of black spruce TMP by using acid hydrogen peroxide: Part 1. A pilot plant study

Walter

Paulsson

Wackerberg

2009

Nordic Pulp &Amp; Paper Research Journal

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SUMMARY:The potential of using acid hydrogen peroxide for lowering the electrical energy consumption during production of Black spruce (Picea mariana) thermomechanical pulp (TMP) was investigated. The chemical system, which consisted of ferrous sulphate, hydrogen peroxide and optionally an enhancer [ethylenediaminetetraacetic acid (sodium salt), 3,4-dimethoxybenzyl (veratryl) alcohol or oxalic acid/sodium oxalate], was evaluated as an inter-stage treatment where the primary refiner was used as a mixer. The approach has the advantage of minimising the capital investment needed for implementation, thus being directly applicable in a thermomechanical pulping process consisting of two or more refiners in series.The results obtained in a pilot plant trial revealed that is was possible to significantly reduce the specific energy consumption by approximately 20 and 35% to a freeness value of 100 ml CSF by using 1 and 2% hydrogen peroxide, respectively. The energy reduction could be obtained without any substantial change in fibre length, fractional composition of the pulp or tensile strength of the paper. The tear strength was slightly reduced however, as was the pulp yield. The major drawback with the acid hydrogen peroxide system was a reduction in brightness by at least 6 brightness units. The addition level of ferrous sulphate was too high and the possibility to reducing the discoloration should be considerable when the chemical system is optimized.

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Section: Acid Hydrogen Peroxidementioning

confidence: 99%

Energy efficient refining of black spruce TMP by using acid hydrogen peroxide: Part 1. A pilot plant study

Walter

Paulsson

Wackerberg

2009

Nordic Pulp &Amp; Paper Research Journal

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“…Although ubiquitous and an important source of reactive oxygen species (ROS), if HO • is indeed produced, the identity of the intermediate formed in this reaction has long been the subject of debate (Goldstein et al, 1993;MacFaul et al, 1998;Walling, 1998;Goldstein and Meyerstein, 1999;Dunford, 2002;Rachmilovich-Calis et al, 2009a;Remucal Keenan and Sedlak, 2011). It is generally accepted that HO • is formed under acidic conditions and in the absence of ligands.…”

Section: Introductionmentioning

confidence: 99%

Importance of Iron Complexation for Fenton-Mediated Hydroxyl Radical Production at Circumneutral pH

2016

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The reaction between Fe(II) and H 2 O 2 to yield hydroxyl radicals (HO • ), the Fenton reaction, is of interest due to its role in trace metal and natural organic matter biogeochemistry, its utility in water treatment and its role in oxidative cell degradation and associated human disease. There is significant dispute over whether HO • , the most reactive of the so-called reactive oxygen species (ROS), is formed in this reaction, particularly under circumneutral conditions relevant to natural systems. In this work we have studied the oxidation kinetics of Fe(II) complexed by L = citrate, ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) and also measured HO • production using phthalhydrazide as a probe compound at pH 8.2. A kinetic model has been developed and utilized to confirm that HO • is the sole product of the Fe(II)L-H 2 O 2 reaction for L = EDTA and DTPA. Quantitative HO • production also appears likely for L = citrate, although uncertainties with the speciation of Fe(II)-citrate complexes as well as difficulties in modeling the oxidation kinetics of these complexes has prevented a definitive conclusion. In the absence of ligands at circumneutral pH, inorganic Fe(II) reacts with H 2 O 2 to yield a species other than HO • , contrary to the well-established production of HO • from inorganic Fe(II) at low pH. Our results suggest that at high pH Fe(II) must be complexed for HO • production to occur.

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“…When experiments with brain homogenates were repeated with 20 M iron, no hydrocodone formation was detected. Although no further studies on the mechanism of the iron-catalyzed demethylation were done, it is well known that Fe II catalyzes nonenzymatic hydroxyl radical formation from H 2 O 2 via the Fenton reaction (62)(63)(64), and thus it is probably not surprising that iron-catalyzed (non-enzymatic) demethylation was observed (see also Ref. 65 for iron-catalyzed N-demethylation of oripavine).…”

Section: Discussionmentioning

confidence: 99%

Cytochrome P450 3A Enzymes Catalyze the O6-Demethylation of Thebaine, a Key Step in Endogenous Mammalian Morphine Biosynthesis

Kramlinger

Rojas

Kanamori

et al. 2015

Journal of Biological Chemistry

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Background: Mammals synthesize endogenous morphine; the enzyme catalyzing thebaine O 6 -demethylation, a key late step, is uncharacterized. Results: Human cytochromes P450 (P450) 3A4 and 3A5 catalyzed thebaine O 6 -demethylation; the P450 3A-selective drug ketoconazole inhibited the reaction in human liver microsomes and rat brain homogenates. Conclusion: P450s 3A4 and 3A5 catalyze thebaine O 6 -demethylation in humans. Significance: Enzymes catalyzing all oxidations in the latter steps of mammalian morphine biosynthesis have been identified.

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Comments on the Mechanism of the “Fenton-Like” Reaction

Cited by 204 publications

References 21 publications

Energy efficient refining of black spruce TMP by using acid hydrogen peroxide: Part 1. A pilot plant study

Energy efficient refining of black spruce TMP by using acid hydrogen peroxide: Part 1. A pilot plant study

Importance of Iron Complexation for Fenton-Mediated Hydroxyl Radical Production at Circumneutral pH

Cytochrome P450 3A Enzymes Catalyze the O6-Demethylation of Thebaine, a Key Step in Endogenous Mammalian Morphine Biosynthesis

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