21393-59-9Relevant articles and documents
Cuprous hydroxide in a solid form: Does it exist?
Soroka, Inna L.,Shchukarev, Andrey,Jonsson, Mats,Tarakina, Nadezda V.,Korzhavyi, Pavel A.
, p. 9585 - 9594 (2013)
Experimental studies have been performed to obtain the unknown cuprous hydroxide compound, which has recently been predicted theoretically (P. A. Korzhavyi et. al., Proc. Natl. Acad. Sci. U. S. A., 2012, 109, 686-689) to be metastable in a solid form. The reduction of Cu2+ with ferrous ethylenediamine tetraacetate (EDTA) results in the formation of a yellow powder precipitate whose composition corresponds to CuOH × H2O as probed by Fourier Transform Infrared Spectroscopy (FTIR) and cryogenic X-ray Photoelectron Spectroscopy (XPS). A similar compound has been found on the surface of Cu-CuH powder stored in water, as detected by XPS. The reduction of Cu2+ to Cu+ with free radicals in aqueous solutions results in a Cu2O precipitate as the final product, while the formation of the yellow cuprous hydroxide colloids may be an intermediate step. Our studies reveal that cuprous hydroxide does exist in a solid form and most likely has a hydrated form, CuOH × H2O. The Royal Society of Chemistry 2013.
Polymer Films on Electrodes. 10. Electrochemical Behavior of Solution Species at Nafion-Tetrathiafulvalenium Bromide Polymers
Henning, Timothy P.,White, Henry S.,Bard, Allen J.
, p. 5862 - 5868 (1982)
The electrochemical behavior of solution species at electrodes consisting of a conductive polymer layer, produced by incorporation of tetrathiafulvalenium (TTF+) bromide into the cation-exchange polymer Nafion, on various substrates (Pt, Ta, SnO2, n-Si) is described.The votlammetric behavior of the solution species Fe(CN)63- and FeY2- (where Y4- = ethylenediaminetetraacetate) at the Nafion-TTF+ electrodes was consistent with models of electrodes partially covered with electronically conductive sites.Microscopic investigation of the electrode showed that the incorporated TTF+ forms electroactive domains and conductive nonelectroactive crystals from electrochemical cycling.The nonelectroactive crystals have the same stoichiometry as the one-dimensional organic conductor TTFBr0.7.In the electrodeposition of copper onto the TTF+ polymer electrode, most deposited on the TTFBr0.7, indicating that they were the major source of electronic conduction within the polymer.When the TTF+ polymer was applied to the surface of an n-type Si electrode, the lifetime of the semiconductor electrode for the photooxydation of Fe(II) species was improved.
Scanning electrochemistry microscopy (SECM) in the study of electron transfer kinetics at liquid/liquid interfaces: Beyond the constant composition approximation
Barker, Anna L.,Unwin, Patrick R.,Amemiya, Shigeru,Zhou, Jungfen,Bard, Allen J.
, p. 7260 - 7269 (1999)
A numerical model is developed for the SECM feedback mode for the case of irreversible electron transfer (ET) processes at the interface between two immiscible electrolyte solutions (ITIES). In this application, a redox-active species is electrogenerated by the reduction/oxidation of the oxidized/reduced form of a couple at an ultramicroelectrode (UME) tip located in one liquid (phase 1). The tip is positioned close to the interface with a second immiscible liquid (phase 2), that contains the oxidized/reduced half of another redox couple. If ET occurs between the tip-generated species in phase 1 and the redox-active species in phase 2, then the original species in phase 1 is regenerated at the interface and undergoes positive feedback at the tip, enhancing the steady-state current. The feedback current, for a given separation between the tip and the interface, is shown to depend on the ratio of the concentrations of the redox-active species in the two phases, their relative diffusion coefficients, and the rate constant for the redox reaction. The results of the model are used to identify the conditions under which (i) diffusion in phase 2 has to be considered and; (ii) a simpler limiting (constant composition) model for phase 2, employed to analyze earlier SECM experiments, can be used. In addition to diversifying the range of conditions under which redox reactions at ITIES can be studied, the results of the model demonstrate that there are considerable advantages to lifting the constant composition restriction on phase 2 for the accurate characterization of rapid redox reactions. The theoretical predictions are examined through experimental studies of electron transfer between the electrogenerated, oxidized form of zinc-21H, 23H-tetraphenylporphine (ZnPor) in benzene or benzonitrile and the reductants Fe(CN)64-, Ru(CN)64-, Mo(CN)84-, or FeEDTA2- (where EDTA denotes ethylenediaminetetraacetic acid) in an aqueous solution. Bimolecular rate constants for each of these systems are reported, with the potential across the ITIES biased with either perchlorate or tetrafluoroborate ions in each phase.
Influence of Co-ordination Number on Copper(I)-Copper(II) Redox Interconversions. Part 3. Reduction of a Sterically Constrained Bis-(substituted phenanthroline) Complex of Copper(II) by Iron(II) and Ruthenium(II) Complexes
Leupin, Peter,Al-Shatti, Najat,Sykes, A. Geoffrey
, p. 927 - 930 (1982)
Further kinetic studies are reported for reduction of the copper(II) complex. 2-, containing the ligand L2- = 2,9-dimethyl-4,7-bis-1,10-phenanthroline.The methyl susbstituents in the 2,9 positions create a steric hidrance which limits the extent of co-ordination to CuII (bis and not tris complexes are formed) and five- and four-(tetrahedral) co-ordinate complexes are believed to be present.With 4-, 2- (edta = ethylenediaminetetra-acetate), 3-, and 2+ (pyz = pyrazine) as reductants (abbreviation Red) limiting kinetics are observed, and a self- consistent interpretation is possible in terms of the sequence: CuII --->CuII (k1,k-1); Red + CuII ---> products (k2), and Red + CuII ---> products (k3).In this sequence CuII and Cu2 are the five- and four-co-ordinate forms respectively.The step k3 is additional to the sequence previously proposed for 4- the results for which have been modified accordingly.Contributions from k3 are not apparent with 3- and 2+, whereas with 2+ (py = pyridine) reaction via k3 appears to be dominant.Possible explanations of the balance between k2 and k3 in terms of different E values and ability to inner-sphere are cnsidered.
Thermal degradation of EDTA chelates in aqueous solution
Motekaitis, Ramunas J.,Cox, III, X. B.,Taylor, Patrick,Martell, Arthur E.,Miles, Brad,Tvedt, Tory J. Jr.
, p. 1207 - 1213 (1982)
The termal degradation of Ca(II), Mg(II), Zn(II), Fe(II), and Ni(II) chelates of EDTA was investigated in alkaline aqueous solution at elevated temperatures (230-310 degC).The kinetics of decomposition were followed by nmr, titrimetry, and spectrophotometry.Reaction products were identified through nmr and by gas chromatography.The relative order of degradation rates, as measured by the loss of EDTA, was found to be Mg(II)>Ca(II)>Zn(II)>Fe(II)>Ni(II).The main degradation products formed in the lower temperature range (cca. 250 degC) are iminodiacetic acid,hydroxyethyliminodiacetic acid, and ethylene glycol.Higher temperature products are primarily dimethylamine and carbon dioxide.The rates of degradation of Ca(II), Mg(II), and Zn(II) EDTA chelates are considerably enhanced when either phosphate is present or a glas-lined autoclave is employed.
5-Carboxamido-5-formamido-2-iminohydantoin, in Addition to 8-oxo-7,8-Dihydroguanine, Is the Major Product of the Iron-Fenton or X-ray Radiation-Induced Oxidation of Guanine under Aerobic Reducing Conditions in Nucleoside and DNA Contexts
Alshykhly, Omar R.,Fleming, Aaron M.,Burrows, Cynthia J.
, p. 6996 - 7007 (2015/07/27)
Exogenously and endogenously produced reactive oxygen species attack the base and sugar moieties of DNA showing a preference for reaction at 2′-deoxyguanosine (dG) sites. In the present work, dG was oxidized by HO? via the Fe(II)-Fenton reaction or by X-ray radiolysis of water. The oxidized lesions observed include the 2′-deoxynucleosides of 8-oxo-7,8-dihydroguanine (dOG), spiroiminodihydantoin (dSp), 5-guanidinohydantoin (dGh), oxazolone (dZ), 5-carboxamido-5-formamido-2-iminohydantoin (d2Ih), 5′,8-cyclo-2′-deoxyguanosine (cyclo-dG), and the free base guanine (Gua). Reactions conducted with ascorbate or N-acetylcysteine as a reductant under aerobic conditions identified d2Ih as the major lesion formed. Studies were conducted to identify the role of O2 and the reductant in product formation. From these studies, mechanisms are proposed to support d2Ih as a major oxidation product detected under aerobic conditions in the presence of the reductant. These nucleoside observations were then validated in oxidations of oligodeoxynucleotide and λ-DNA contexts that demonstrated high yields of d2Ih in tandem with dOG, dSp, and dGh. These results identify dG oxidation to d2Ih to occur in high yields leading to a hypothesis that d2Ih could be found from in cells stressed with HO?. Further, the distorted ring structure of d2Ih likely causes this lesion to be highly mutagenic. (Chemical Equation Presented)
ALGICIDAL COMPOUND
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Page 6, (2010/02/09)
A new algicidal compound is devised.
Kinetics and reaction mechanism of the liquid-phase oxidation of hydrogen sulfide by a chelate complex of trivalent iron (Fe3+EDTA-)
Neyaglov,Digurov,Bukharkina,Mazgarov,Fakhriev
, p. 485 - 489 (2008/10/08)
A kinetics model is obtained and a mechanism proposed for the reaction of Fe3+EDTA- with hydrogen sulfide that are consistent with the experimental data. It is established that the reaction takes place via an intermediate complex, [Y], and is autocatalytic. This is explained by the accumulation of polysulfides. The reaction parameters are determined.
Kinetics and reaction mechanism of the liquid-phase oxidation of mercaptans by an Fe3+EDTA - chelate complex
Neyaglov,Digurov,Bukharkina,Mazgarov,Fakhriev
, p. 479 - 485 (2008/10/08)
A mechanism is proposed and a kinetic model is obtained for the reaction of Fe3+EDTA- with ethyl and n-propyl mercaptans. It is established that the reaction proceeds via formation of an intermediate complex, [X], in the formation of which specific acid/base forms of the reactants take part. The dependence of the reaction rate on the pH of the medium is explained by this fact. Rate equations are obtained that adequately describe the experimental data up to the deep conversion of the starting materials, and the rate constants determined.
Spin-trapping studies of the reduction of O2 and H2O2 by titanium(III), iron(II), and ruthenium(II) complexes
Johnson, Craig R.,Myser, Terry K.,Shepherd, Rex E.
, p. 1089 - 1095 (2008/10/08)
The reductions of H2O2 and O2 by Ti(edta)(H2O)-, Ti(H2O)63+, Fe(edta)2-, Fe(H2O)62+, and Ru(NH3)62+ have been studied by the spin-trapping technique using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and N-tert-butyl-α-phenylnitrone (PBN) radical traps. The resultant radical adducts RDMPO? and RPBN? have been characterized by ESR spectroscopy in agreement with literature values. Ti(edta)(H2O)-, Fe(edta)2-, Fe(H2O)62+, and Ru(NH3)62+ reductions of H2O2 produce HO? identified by the HO-DMPO? and HO-PBN? spectra. HO? formed in these reductions may be intercepted by chemical mediators (CH3OH, C2H5OH, (CH3)2CO, (CH3)3COH) to provide more long-lived secondary carbon-centered radicals, which are trapped by DMPO or PBN. Excellent spectral matches for RDMPO? and RPBN? species are obtained for the Ti(edta)(H2O)-, Fe(edta)2-, Fe(H2O)62+, Ti(H2O)63+, and Ru(NH3)62+ reductants for H2O2 in the presence or absence of mediators. When O2 is used as the oxidant for Ru(NH3)62+, this reaction known to proceed outer sphere via O2-, only the dismutation/reduction product (HO?) is trapped at pH 6.86. Both HO2? and HO? are trapped at pH 2.57 in a 1.0:7.6 ratio. Ti(edta)(H2O)- is known to be oxidized inner sphere by O2 via coordinated O2-. No radical adducts for the Ti(edta)(H2O)-/O2/radical trap system are observed with or without mediators in the solvent cage. The reduction of O2 by either Fe(edta)2- or Fe2(ttha)2- proceeds by an inner-sphere pathway in which the coordinated O2- survives long enough to attack an adjacent carboxylate moiety, forming a trappable ligand-based carbon-centered radical, or to attack sacrificial mediators in the solvent cage.
