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Urs Von Gunten - One of the best experts on this subject based on the ideXlab platform.

  • Reactions of Ferrate(VI) with Iodide and Hypoiodous Acid: Kinetics, Pathways, and Implications for the Fate of Iodine during Water Treatment
    Environmental science & technology, 2018
    Co-Authors: Jaedon Shin, Urs Von Gunten, David A. Reckhow, Sebastien Allard, Yunho Lee
    Abstract:

    Oxidative treatment of iodide-containing waters can form toxic iodinated disinfection byproducts (I-DBPs). To better understand the fate of iodine, kinetics, products, and stoichiometries for the reactions of ferrate(VI) with iodide (I–) and Hypoiodous Acid (HOI) were determined. Ferrate(VI) showed considerable reactivities to both I– and HOI with higher reactivities at lower pH. Interestingly, the reaction of ferrate(VI) with HOI (k = 6.0 × 103 M–1 s–1 at pH 9) was much faster than with I– (k = 5.6 × 102 M–1 s–1 at pH 9). The main reaction pathway during treatment of I–-containing waters was the oxidation of I– to HOI and its further oxidation to IO3– by ferrate(VI). However, for pH > 9, the HOI disproportionation catalyzed by ferrate(VI) became an additional transformation pathway forming I– and IO3–. The reduction of HOI by hydrogen peroxide, the latter being produced from ferrate(VI) decomposition, also contributes to the I– regeneration in the pH range 9–11. A kinetic model was developed that could w...

  • Reactions of Ferrate(VI) with Iodide and Hypoiodous Acid: Kinetics, Pathways, and Implications for the Fate of Iodine during Water Treatment
    2018
    Co-Authors: Jaedon Shin, Urs Von Gunten, David A. Reckhow, Sebastien Allard, Yunho Lee
    Abstract:

    Oxidative treatment of iodide-containing waters can form toxic iodinated disinfection byproducts (I-DBPs). To better understand the fate of iodine, kinetics, products, and stoichiometries for the reactions of ferrate­(VI) with iodide (I–) and Hypoiodous Acid (HOI) were determined. Ferrate­(VI) showed considerable reactivities to both I– and HOI with higher reactivities at lower pH. Interestingly, the reaction of ferrate­(VI) with HOI (k = 6.0 × 103 M–1 s–1 at pH 9) was much faster than with I– (k = 5.6 × 102 M–1 s–1 at pH 9). The main reaction pathway during treatment of I–-containing waters was the oxidation of I– to HOI and its further oxidation to IO3– by ferrate­(VI). However, for pH > 9, the HOI disproportionation catalyzed by ferrate­(VI) became an additional transformation pathway forming I– and IO3–. The reduction of HOI by hydrogen peroxide, the latter being produced from ferrate­(VI) decomposition, also contributes to the I– regeneration in the pH range 9–11. A kinetic model was developed that could well simulate the fate of iodine in the ferrate­(VI)-I– system. Overall, due to a rapid oxidation of I– to IO3– with short-lifetimes of HOI, ferrate­(VI) oxidation appears to be a promising option for I-DBP mitigation during treatment of I–-containing waters

  • reactions of Hypoiodous Acid with model compounds and the formation of iodoform in absence presence of permanganate
    Water Research, 2017
    Co-Authors: Xiaodan Zhao, Urs Von Gunten
    Abstract:

    The kinetics for the reactions of Hypoiodous Acid (HOI) with various phenols (phenol, 4-nitrophenol, 4-hydroxybenzoic Acid), 3-oxopentanedioic Acid (3-OPA) and flavone were investigated in the pH range of 6.0–11.0. The apparent second order rate constants for the reactions of HOI with phenolic compounds, 3-OPA, flavone and citric Acid at pH 8.0 are 10–107 M−1s−1, (4.0 ± 0.3) × 103 M−1s−1, (2.5 ± 0.2) × 103 M−1s−1 and  8.0, in presence of permanganate, iodoform formation is significantly inhibited and iodate formation enhanced, which is due to a faster permanganate-mediated HOI disproportionation to iodate compared to the iodination process. The production of reactive iodine in real waters containing iodide in contact with permanganate may lead to the formation of iodinated organic compounds.

  • Reactions of Hypoiodous Acid with model compounds and the formation of iodoform in absence/presence of permanganate
    Water research, 2017
    Co-Authors: Xiaodan Zhao, Urs Von Gunten
    Abstract:

    The kinetics for the reactions of Hypoiodous Acid (HOI) with various phenols (phenol, 4-nitrophenol, 4-hydroxybenzoic Acid), 3-oxopentanedioic Acid (3-OPA) and flavone were investigated in the pH range of 6.0–11.0. The apparent second order rate constants for the reactions of HOI with phenolic compounds, 3-OPA, flavone and citric Acid at pH 8.0 are 10–107 M−1s−1, (4.0 ± 0.3) × 103 M−1s−1, (2.5 ± 0.2) × 103 M−1s−1 and  8.0, in presence of permanganate, iodoform formation is significantly inhibited and iodate formation enhanced, which is due to a faster permanganate-mediated HOI disproportionation to iodate compared to the iodination process. The production of reactive iodine in real waters containing iodide in contact with permanganate may lead to the formation of iodinated organic compounds.

  • Kinetic and Mechanistic Aspects of the Reactions of Iodide and Hypoiodous Acid with Permanganate: Oxidation and Disproportionation.
    Environmental science & technology, 2016
    Co-Authors: Xiaodan Zhao, Elisabeth Salhi, Huiling Liu, Urs Von Gunten
    Abstract:

    Oxidation kinetics of iodide and HOI/OI– by permanganate were studied in the pH range of 5.0–10.0. Iodide oxidation and iodate formation were faster at lower pH. The apparent second-order rate constants (kobs) for iodide oxidation by permanganate decrease with increasing pH from 29 M–1 s–1 at pH 5.0 and 6.9 M–1 s–1 at pH 7.0 to 2.7 M–1 s–1 at pH 10.0. kobs for HOI abatement are 56 M–1 s–1 at pH 5.0, 2.5 M–1 s–1 at pH 7.0, and 173 M–1 s–1 at pH 10.0. Iodate yields over HOI abatement decrease from 98% at pH 6.0 to 33% for pH ≥ 9.5, demonstrating that HOI disproportionation dominates HOI transformation by permanganate at pH ≥ 8.0. MnO2 formed as a product from permanganate reduction, oxidizes HOI to iodate for pH < 8.0, and promotes HOI disproportionation for pH ≥ 8.0. The rate of HOI oxidation or disproportionation induced by MnO2 is much lower than for permanganate. During treatment of iodide-containing waters, the potential for iodinated disinfection byproducts (I-DBPs) formation is highest at pH 7.0–8.0 ...

Jie Yan - One of the best experts on this subject based on the ideXlab platform.

  • Selective synthesis of 3‐Selanylindoles from Indoles and Diselenides using IK/mCPBA system
    Applied Organometallic Chemistry, 2017
    Co-Authors: Xiaolong Wang, Jie Yan
    Abstract:

    In the presence of a catalytic amount of KI combined with oxidant mCPBA, a convenient catalytic procedure is developed for the preparation of 3-selanylindoles from indoles and diselenides. In this protocol, KI is first oxidized by mCPBA into Hypoiodous Acid, which reacts with diselenide to cleave Se-Se bond. The in situ generated active electrophilic selenium species then reacts with indole, affording 3-selanylindole via an electrophilic substitution mechanism. This catalytic selenation of indoles has mild reaction conditions and is a simple procedure, which extends the synthetic application of KI in organic synthesis.

  • A Convenient Catalytic Procedure for Direct Synthesis of Aryl­selanyl Anilines
    Synlett, 2015
    Co-Authors: Hongwei Shi, Min Zhu, Jie Yan
    Abstract:

    In the presence of a catalytic amount of KI combined with oxidant H2O2, a convenient catalytic procedure has been developed for the direct preparation of arylselanyl anilines from N,N-disubstituted anilines and diselenides. In this protocol, KI is first oxidized by H2O2 into Hypoiodous Acid, which promotes the cleavage of Se–Se bond in diselenide. The in situ generated active electrophilic selenium species then reacts with N,N-disubstituted aniline, affording 4-arylselanyl aniline with high regioselectivity and good yield via an electrophilic substitution. This metal-free catalytic method is convenient in neutral condition at room temperature and in short time, not only arylselanyl anilines, but also alkaylselanyl anilines have been prepared, which extends the catalytic application of KI in organic synthesis.

  • Novel α-Tosyloxylation of Ketones Catalyzed by the in situ Generated Hypoiodous Acid from Alkyl Iodide.
    ChemInform, 2015
    Co-Authors: Bijun Zhang, Liuquan Han, Jie Yan
    Abstract:

    Not only α-tosyloxyketones, but also other α-sulfonyloxyketones can be synthesized following this catalytic reaction.

  • Novel α-tosyloxylation of ketones catalyzed by the in situ generated Hypoiodous Acid from alkyl iodide
    Tetrahedron Letters, 2014
    Co-Authors: Bijun Zhang, Liuquan Han, Jie Yan
    Abstract:

    Using a catalytic amount of 1-iodopropane, a novel and efficient procedure has been developed for direct preparation of α-tosyloxyketones from ketones. In this protocol, 1-iodopropane is first oxidized into iodosylpropane, which decomposes to form the key catalyst Hypoiodous Acid. With this method, not only α-tosyloxyketones, but also other α-sulfonyloxyketones have been prepared in moderate to good yields, which extends the application of alkyl substituted hypervalent iodine reagents in organic synthesis.

Arantxa Rodriguez - One of the best experts on this subject based on the ideXlab platform.

Vladimir E Bondybey - One of the best experts on this subject based on the ideXlab platform.

  • Hypoiodous Acid as guest molecule in protonated water clusters: a combined FT-ICR/DFT study of I(H2O)n+.
    Journal of the American Chemical Society, 2001
    Co-Authors: Uwe Achatz, Brigitte S Fox, Martin K Beyer, Vladimir E Bondybey
    Abstract:

    Cationic water clusters containing iodine, of the composition I(H2O)n+, n = 0-25, are generated in a laser vaporization source and investigated by FT-ICR mass spectrometry. An investigation of blackbody radiation-induced fragmentation of size-selected clusters I(H2O)n+, n = 3-15, under collision-free conditions revealed an overall linear increase of the unimolecular rate constant with cluster size, similar to what has been observed previously for other hydrated ions. Above a certain critical size, I(H2O)n+, n greater than or approx. 13, reacts with HCl by formation of the interhalide ICl and a protonated water cluster, which is the reverse of a known solution-phase reaction. Accompanying density functional calculations illustrate the conceptual differences between cationic and anionic iodine-water clusters I(H2O)n+/-. While I-(H2O)n is genuinely a hydrated iodide ion, the cationic closed-shell species I(H2O)n+ may be best viewed as a protonated water cluster, in which one water molecule is replaced by Hypoiodous Acid. In the strongly Acidic environment, HOI is protonated because of its high proton affinity. However, similar to the well-known H3O+/H5O2+ controversy in protonated water clusters, a smooth transition between H2IO+ and H4IO2+ as core ions is observed for different cluster sizes.

  • Hypoiodous Acid as guest molecule in protonated water clusters a combined ft icr dft study of i h2o n
    Journal of the American Chemical Society, 2001
    Co-Authors: Uwe Achatz, Brigitte S Fox, Martin K Beyer, Vladimir E Bondybey
    Abstract:

    Cationic water clusters containing iodine, of the composition I(H2O)n+, n = 0-25, are generated in a laser vaporization source and investigated by FT-ICR mass spectrometry. An investigation of blackbody radiation-induced fragmentation of size-selected clusters I(H2O)n+, n = 3-15, under collision-free conditions revealed an overall linear increase of the unimolecular rate constant with cluster size, similar to what has been observed previously for other hydrated ions. Above a certain critical size, I(H2O)n+, n greater than or approx. 13, reacts with HCl by formation of the interhalide ICl and a protonated water cluster, which is the reverse of a known solution-phase reaction. Accompanying density functional calculations illustrate the conceptual differences between cationic and anionic iodine-water clusters I(H2O)n+/-. While I-(H2O)n is genuinely a hydrated iodide ion, the cationic closed-shell species I(H2O)n+ may be best viewed as a protonated water cluster, in which one water molecule is replaced by Hypoiodous Acid. In the strongly Acidic environment, HOI is protonated because of its high proton affinity. However, similar to the well-known H3O+/H5O2+ controversy in protonated water clusters, a smooth transition between H2IO+ and H4IO2+ as core ions is observed for different cluster sizes.

Wesley J. Moran - One of the best experts on this subject based on the ideXlab platform.