14996-02-2Relevant articles and documents
Oscillations and Bistability in the Cu(II)-Catalyzed Reaction between H2O2 and KSCN
Orban, Miklos
, p. 6893 - 6898 (1986)
The reaction between H2O2 and KSCN catalyzed by CuSO4 exhibits three different types of bistability as a function of flow rate in a continuous flow stirred tank reactor at 25 deg C.Two steady states and one oscillatory state are involved.The system is one of the few examples in which oscillations can appear in batch configuration as well.The color, the potential of a Pt electrode, and the rate of oxygen gas evolution oscillate for a wide range of reagent concentrations.The chemistry which accounts for the observed behavior is discussed briefly.
Oxidation of biologically relevant chalcogenones and their Cu(I) complexes: Insight into selenium and sulfur antioxidant activity
Kimani, Martin M.,Bayse, Craig A.,Stadelman, Bradley S.,Brumaghim, Julia L.
supporting information, p. 11685 - 11687 (2013/11/19)
Hydroxyl radical damage to DNA causes disease, and sulfur and selenium antioxidant coordination to hydroxyl-radical-generating Cu+ is one mechanism for their observed DNA damage prevention. To determine how copper binding results in antioxidant
One- versus two-electron oxidation with peroxomonosulfate ion: reactions with iron(II), vanadium(II), halide ions, and photoreaction with cerium(III)
Lente, Gabor,Kalmar, Jozsef,Baranyai, Zsuzsa,Kun, Aliz,Kek, IIdikoe,Bajusz, David,Takacs, Marcell,Veres, Lilla,Fabian, Istvaen
, p. 1763 - 1773 (2009/06/17)
The kinetics of the redox reactions of the peroxomonosulfate ion (HSO 5-) with iron(ll), vanadium(IV), cerium(lll),chloride, bromide, and iodide ions were studied. Cerium(lll) is only oxidized upon illumination by UV light and cerium
Effect of dissolved oxygen on the oxidation of dithionate ion. Extremely unusual kinetic traces
Lente, Gabor,Fabian, Istvan
, p. 4019 - 4025 (2008/10/09)
The effect of dissolved oxygen on the acid-dependent disproportionation of dithionate ion (S2O62-) and its oxidation with a number of reagents (I2, Br2, I3-, Br3-, IO3-, BrO3 -, IO4-, MnO4-, Cr(VI), Ce(VI), and H2O2) were studied. Dithionate ion is remarkably inert at room temperature, and heating to elevated temperatures (50-90 °C) was necessary to observe detectable reaction rates in all of these processes. It was confirmed that dithionate ion is never oxidized directly; its redox reactions are zeroth-order with respect to the oxidizing agent and proceed through disproportionation and subsequent fast oxidation of the sulfur(IV) formed. The effect of dissolved oxygen is attributable to its reaction with sulfur(IV) produced in the disproportionation. This autoxidation occurs only with a catalyst. Cerium(III) and iodide ions were shown to catalyze the autoxidation, and their effect on the kinetic traces was studied. In a few cases, highly unusual kinetic traces, such as straight lines with sharp break points, inverted parabolas, and a combination of these, were detected and successfully interpreted in terms of simple kinetic and stoichiometric considerations.
Temperature dependence of adlayers on Pt(1 1 1) and Au(1 1 1) in a sulfuric acid solution studied by in situ IRAS
Shingaya,Ito
, p. 425 - 430 (2008/10/08)
Temperature dependence studies of adsorption of sulfuric acid species on Pt(111) and Au(111) electrodes were carried out using in situ infrared reflection absorption spectroscopy. A temperature-dependent shift of the interconversion potential between HSO4-/H3O+ and H2SO4 on a Pt(111) electrode was observed. A temperature-dependent frequency shift of the absorption bands of HSO4- was also observed on both Pt(111) and Au(111) electrodes in the potential region where a √3×√7 structure evolved. Modelling experiments in ultrahigh vacuum revealed that ordering of the overlayer water molecules played an important role in the frequency of the absorption bands of HSO4-.
Orthorhombic B2CN crystal synthesized by high pressure and temperature
He,Tian,Yu,Wang,Liu,Guo,Li,Jia,Chen,Zou,Yanagisawa
, p. 431 - 436 (2008/10/08)
B0.54C0.28N0.18 precursor powder with turbostratic structure was prepared by using melamine and boric acid. The precursor was transformed into orthorhombic B2CN under definite high pressure and temperature conditions. The composition of the orthorhombic B2CN powder is B0.47C0.23N0.30. Its lattice parameters are a=0.4776 nm, b=0.4585 nm and c=0.3629 nm. A strong absorption band from 1088 to 1385cm-1 of orthorhombic B2CN was observed by infrared measurement. In the photoluminescence (PL) spectrum of orthorhombic B2CN powder measured at room temperature, a broad peak corresponding to its band-edge emission centers at 374 nm.
Thiocyanogen as an intermediate in the oxidation of thiocyanate by hydrogen peroxide in acidic aqueous solution
Figlar,Stanbury
, p. 5089 - 5094 (2008/10/08)
The kinetics of the reaction of H2O2 with excess SCN- in acidic media was studied by use of Ti(IV) as an indicator for the concentration of H2O2. Pseudo-first-order behavior was realized by this method, and these data confirm the acid-catalyzed rate law and rate constant reported some 40 years ago for this reaction under conditions of excess H2O2. Under the same conditions except without Ti(IV), repetitive-scan spectra reveal the formation and decay of an intermediate that absorbs in the UV. In the proposed mechanism, HOSCN is produced in the first step and it is converted rapidly to (SCN)2 through its equilibrium reaction with SCN-. The observed intermediate is believed to be (SCN)2, which decays on a longer time scale. Excellent global fits of this mechanism to the repetitive-scan data are obtained with rate constants constrained by the Ti(IV) data and published previously in our study of the ClO2/SCN- reaction. These fits yield a spectrum for (SCN)2 that is characterized by λ(max) = 297 nm and ε297 = 147.M-1 cm-1, in fine agreement with our prior report.
Rate constants for the reactions of XO3-(H2O)n (X = C, HC, and N) and NO3-(HNO3)n with H2SO4: Implications for atmospheric detection of H2
Viggiano,Seeley,Mundis,Williamson,Morris
, p. 8275 - 8278 (2007/10/03)
Relative rate constants for the reactions of CO3-(H2O)n, HCO3-(H2O)n, NO3-(H2O)n, and NO3-(HNO3
Gas-phase reactions of weak br?nsted bases I-, PO3-, HSO4-,FSO3 -, and CF3so3- with strong br?nsted acids H2so4, FSO3H, and CF3so3H.
Viggiano,Henchman,Dale,Deakyne,Paulson
, p. 4299 - 4306 (2007/10/02)
Using a selected ion flow tube at 368 K, we have measured rate constants for ion-molecule reactions between I-, PO-, HSO4-, FSO3-, CF3SO3-, NO3-·HNO3, FSO3-·FSO3H, and H2SO4, FSO3H, CF3SO3H. Channels observed include proton transfer and clustering. These results allow free energies (enthalpies) of deprotonation (kJ/mol) to be estimated (within ±10 kJ/mol) as follows: HPO3, 1270 (1300); H2SO4, 1265 (1295); FSO3H, 1255 (1285); CF3SO3H, 1250 (1280). In two cases, electron affinities are estimated as follows: HSO4, 4.7 ± 0.2 eV. FSO3, 4.8 ± 0.2 eV. For the title acids, the gas-phase acidity order is discussed and is used to explain the differing acidity orders found for these acids in different solvents. The same data measure basicities for the conjugate bases, and these are related to nucleophilicity and leaving group ability. This study explores a region of the acidity scale where no acidities are established that would calibrate the scale. The scale is calibrated here using cluster ions whose free energy of protonation can be reliably estimated.
Kinetics and Mechanism of the BrO3(1-)-SCN(1-)-H(1+) Reaction
Zhang, Yi-Xue,Field, Richard J.
, p. 1224 - 1228 (2007/10/02)
The reaction of BrO3(1-) with SCN(1-) in dilute HClO4 is investigated in both batch and flow reactor modes.The stoichiometry of the reaction is BrO3(1-) + SCN(1-) + H2O -> HSO4(1-) + HCN + Br(1-) when SCN(1-) is in excess and 7BrO3(1-) + 5SCN(1-) + 2H(1+) -> 5BrCN + Br2 + 5SO4(2-) + H2O when BrO3(1-) is in excess.There is a two-stage induction period in the batch mode when BrO3(1-) is in excess before the occurrence of a third stage in which Br2 finally accumulates.The end of the first stage corresponds to the consumption of SCN(1-), and the end of the second corresponds to the consumption of CN(1-).Both of these species react rapidly with Br2.Bromine accumulates during the third stage as a result of the reaction of Br(1-) with BrO3(1-).A large range of feed-stream concentrations and flow rates was investigated in CSTR mode.No periodic or quasiperiodic oscillations were found that could not be eliminated by substituting gravity feeding for a peristaltic pump.However, the system is very sensitive to environmental perturbation and thus very noisy at low flow rates.The reaction is simulated on the basis of a mechanism proposed here.The agreement between experiments and simulations is very good.Simulations at low flow rates show a very rapid change with flow rate of steady-state along a line connecting the three stages mentioned above with BrO3(1-) in excess.This is likely the source of the experimental sensitivity to perturbation.
