Non-metal redox kinetics: hypobromite and hypoiodite reactions with cyanide and the hydrolysis of cyanogen halides

Gerritsen, Cynthia M.; Gazda, Michael; Margerum, Dale W.

doi:10.1021/ic00077a016

Cited by 31 publications

(29 citation statements)

References 3 publications

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“…It was recently showed that LPO oxidation of I − and SCN − favored the formation of ICN in basic conditions, with a positive I − :SCN − ratio. In particular a pH 8.0 and an I − :SCN − ratio of 2:1 doubled the ICN concentration as compared to pH 5.0 and a ratio of 4:1, respectively, with 13 C‐NMR signal of 51 – 53 ppm for enzymatic solution and 50.35 ppm for ICN pure compound and 51.1 – 51.8 ppm for ICN in I − solutions …”

Section: Resultsmentioning

confidence: 99%

“…In particular a pH 8.0 and an I À :SCN À ratio of 2:1 doubled the ICN concentration as compared to pH 5.0 and a ratio of 4:1, respectively, with 13 C-NMR signal of 51 -53 ppm for enzymatic solution and 50.35 ppm for ICN pure compound and 51.1 -51.8 ppm for ICN in I À solutions. [33] [60] Production of I 2 SCN À and I(SCN) À 2 from the Reaction between ICN and SCN À To clarify the nature of our signal at 49.7 ppm, which show acidic preference for its formation, with ICN Table 3. having a similar 13 C signal but presenting basic preference for its formation, and to clarify the nature of the signal at 103.64 ppm, additional experiments were performed.…”

Section: Influence Of the Relative Concentration Of Thiocyanate And Imentioning

confidence: 95%

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Reaction Product Variability and Biological Activity of the Lactoperoxidase System Depending on Medium Ionic Strength and pH, and on Substrate Relative Concentration

Bafort

Damblon

Smargiasso

et al. 2018

Chemistry & Biodiversity

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The potential of ions produced in water by the lactoperoxidase system against plant pests has shown promising results. We tested the bioactivity of ions produced by the lactoperoxidase oxidation of I and SCN in several buffers or in tap water and characterized the ions produced. In vitro biological activity was tested against Penicillium expansum, the causal agent of mold in fruits, and the major cause of patulin contamination of fruit juices and compotes. In buffers, the ionic concentration was increased 3-fold, and pathogen inhibition was obtained down to the 1:15 dilution. In tap water, the ionic concentration was weaker, and pathogen inhibition was obtained only down to the 1:3 dilution. Acidic buffer increased ion concentrations as compared to less acidic (pH 5.6 or 6.2) or neutral buffers, as do increased ionic strength. C-labelled SCN and MS showed that different ions were produced in water and in buffers. In specific conditions the ion solution turned yellow and a product was formed, probably diiodothiocyanate (I SCN ), giving an intense signal at 49.7 ppm in C-NMR. The formation of the signal was unambiguously favored in acidic media and disadvantaged or inhibited in neutral or basic conditions. It was enhanced at a specific SCN : I ratio of 1:4.5, but decreased when the ratio was 1:2, and was inhibited at ratio SCN >I . We demonstrated that the formation of the signal required the interaction between I and SCN , and MS showed the presence of I SCN .

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Section: Resultsmentioning

confidence: 99%

Section: Influence Of the Relative Concentration Of Thiocyanate And Imentioning

confidence: 95%

Reaction Product Variability and Biological Activity of the Lactoperoxidase System Depending on Medium Ionic Strength and pH, and on Substrate Relative Concentration

Bafort

Damblon

Smargiasso

et al. 2018

Chemistry & Biodiversity

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“…The hydrolysis of XCN compounds is known to be base-catalyzed, and can be susceptible to anion complexation (Bailey and Bishop, 1973;Gerritsen et al, 1993) in a manner similar to CH3NCO:…”

Section: Solubility and Reactions Of Xcn Compoundsmentioning

confidence: 99%

“…This is consistent with the results of this study which found that the first-order loss rate was zero, within the error of the linear fit (±4.2 ×10 -4 sec -1 ). The study of BrCN hydrolysis of Gerritsen et al, 1993 did not derive kw nor did it present sufficient data for kw to be estimated. However, there are two other studies that presented data from which kw can be estimated, and those range from 1.9 -9.2 ×10 -5 sec -1 , (Heller-Grossman et al, 1999;Vanelslander et al, 2012).…”

Section: Solubility and Reactions Of Xcn Compoundsmentioning

confidence: 99%

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Solubility and Solution-phase Chemistry of Isocyanic Acid, Methyl Isocyanate, and Cyanogen Halides

Roberts¹,

Liu²

2018

Preprint

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Abstract. Condensed phase uptake and reaction are import atmospheric removal processes for reduced nitrogen species, isocyanic acid (HNCO), methyl isocyanate (CH3NCO) and cyanogen halides (XCN, X =Cl, Br, I), yet many of the fundamental quantities that govern this chemistry have not been measured or are understudied. Solubilities and first-order reaction rate of these species were measured for a variety of solutions using a bubble flow reactor method with total reactive nitrogen (Nr) detection. The aqueous solubility of HNCO was measured as a function of pH, and exhibited the classic behavior of a weak acid, with an intrinsic Henry's law solubility of 20 (&#177;2)&#8201;M/atm, and a Ka of 2.0 (&#177;0.28)&#8201;&#215;&#8201;10&#8722;4&#8201;M (which corresponds to pKa&#8201;=&#8201;3.7&#8201;&#177;&#8201;0.06) at 298&#8201;K. The temperature dependence of HNCO solubility was very similar to other small nitrogen-containing compounds and the dependence on salt concentration exhibited the &#8220;salting out&#8221; phenomenon that was also similar to small polar molecules. The rate constant of reaction of HNCO with 0.45&#8201;M&#8201;NH4+ was measured at pH&#8201;=&#8201;3, and found to be 1.2 (&#177;0.1)&#8201;&#215;&#8201;10&#8722;3&#8201;M&#8722;1&#8201;sec&#8722;1, which is much faster than the rate that would be estimated from rate measurements at much higher pHs, and the assumption that the mechanism is solely by reaction of the un-dissociated acid with NH3. The solubilities of HNCO in the non-polar solvents n-octanol (n-C8H17OH) and tridecane (C13H28) were found to be higher than aqueous solution for n-octanol (87&#8201;&#177;&#8201;3&#8201;M/atm at 298&#8201;K) and much lower than aqueous solution for tridecane (1.7&#8201;&#177;&#8201;0.17&#8201;M/atm at 298&#8201;K), but the first-order loss rate of HNCO in n-octanol was determined to be relatively slow 5.7 (&#177;1.4)&#8201;&#215;&#8201;10&#8722;5sec&#8722;1. The aqueous solubility of CH3NCO was measured at several pHs and found to be 1.3 (&#177;0.13)&#8201;M/atm independent of pH, and CH3NCO solubility in n-octanol was also determined at several temperatures and ranged from 4.0 (&#177;0.5) to 2.8 (&#177;0.3)&#8201;M/atm. The aqueous hydrolysis of CH3NCO was observed to be slightly acid-catalyzed, in agreement with literature values, and reactions with n-octanol ranged from 2.5 (&#177;0.5) to 5.3 (&#177;0.7)&#8201;&#215;&#8201;10&#8722;3&#8201;sec&#8722;1 from 298 to 310&#8201;K. The aqueous solubilities of XCN was determined at room temperature and neutral pH were found to increase with halogen atom polarizability from 1.4 (&#177;0.2)&#8201;M/atm for ClCN, 8.2 (&#177;0.8)&#8201;M/atm for BrCN, to 270 (&#177;41)&#8201;M/atm for ICN. Hydrolysis rates where measurable, were in agreement with literature values. The atmospheric loss rates of HNCO, CH3NCO, and XCN due to heterogeneous processes are estimated from solubilities and reaction rates. Lifetimes of HNCO range from about 1 day against deposition to neutral pH surfaces in the boundary layer, but otherwise can be as long as several months in the mid troposphere. The loss of CH3NCO due to aqueous phase processes is estimated to be slower than, or comparable to, the lifetime against OH reaction (3 months). The loss of XCNs due to aqueous uptake are estimated to range from quite slow, lifetime of 2&#8211;6 months or more for ClCN, 1 week to 6 months for BrCN, to 1 to 10 days for ICN. These characteristic times are shorter than photolysis lifetimes for ClCN, and BrCN, implying that heterogeneous chemistry will be the controlling factor in their atmospheric removal. In contrast, the photolysis of ICN is estimated to be faster than heterogeneous loss for average mid-latitude conditions.

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Mechanism of boron acid/polyol complex formation. comments on the trigonal/tetrahedral interconversion on boron

Pizer

Tihal

1996

Polyhedron

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Non-metal redox kinetics: hypobromite and hypoiodite reactions with cyanide and the hydrolysis of cyanogen halides

Cited by 31 publications

References 3 publications

Reaction Product Variability and Biological Activity of the Lactoperoxidase System Depending on Medium Ionic Strength and pH, and on Substrate Relative Concentration

Reaction Product Variability and Biological Activity of the Lactoperoxidase System Depending on Medium Ionic Strength and pH, and on Substrate Relative Concentration

Solubility and Solution-phase Chemistry of Isocyanic Acid, Methyl Isocyanate, and Cyanogen Halides

Mechanism of boron acid/polyol complex formation. comments on the trigonal/tetrahedral interconversion on boron

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