共查询到20条相似文献,搜索用时 31 毫秒
1.
The reaction of gold(III) neutral complexes AuBr(CN)2(N–N) {N–N = 2,2′-bipyridine (bpy), 5,5′-dimethyl-2,2′-bipyridine (Me2bpy), 1,10-phenanthroline (phen)} with a stoichiometric amount of K[AuCl4] · 2H2O in nitromethane at room temperature led to the formation of 1:1 electrolytes which were characterized by NMR and IR spectroscopy,
conductivity measurements, elemental analyses and X-ray diffraction. Both the anions and the cations of these salts are singly
charged square-planar Au(III) complexes and the cations have general formula [AuCl2(N–N)]+. A hypothesis on the possible reaction mechanisms is presented to give an explanation for the formation of the reaction products. 相似文献
2.
Effect of dioctyl sulfide on the kinetics of oxidative dissolution of gold nanoparticles in triton N-42 reverse micelles 总被引:1,自引:0,他引:1
V. V. Tatarchuk A. I. Bulavchenko I. A. Druzhinina A. P. Sergievskaya 《Russian Journal of Inorganic Chemistry》2011,56(5):808-815
The effect of additions of hydrophobic dioctyl sulfide (L) on the kinetics of dissolution of gold nanoparticles in the interaction
with a dispersed aqueous hydrochloric solution of H2O2 in Triton N-42 reverse micelles (decane was the dispersion medium) was studied spectrophotometrically. The process consists
of a two-stage oxidation Au0 → AuCl2− → AuCl4− at the surface of gold particles; the first stage occurs in two ways: a spontaneous reaction and an autocatalytic reaction
involving AuCl4− ions. With small additions of L (c
L < c
Au), only spontaneous oxidation of Au(0) to Au(I) takes place because Au(I) is completely bound in an inert complex AuLCl. When
unbound L is exhausted, the newly formed AuLCl is accumulated in micellar shells, changes the properties of the medium inside
the micelles, and affects the rate constant of the autocatalytic reaction, which increases with increasing c
L. At high concentrations of L, the coagulation of particles occurs instead of their dissolution, because of the deterioration
of the protective properties of micellar shells as a result of the ingression and accumulation of dioctyl sulfide molecules
on account of selective adsorption on gold particles. The rate constants of all stages of dissolution and coagulation are
determined. 相似文献
3.
The kinetics of the reaction between glycolaldehyde (GA) and tetrachloroaurate(III) in acetic acid-sodium acetate buffer has been studied. The reaction is first-order with respect to [AuIII] as well as [GA]. Both H+ and Cl− ions retard the rate of reaction. AuCl4−, AuCl3(OH2), and AuCl3(OH)− are the reactive species of gold(III) with gradually increasing reactivity. A reaction mechanism involving two-electron transfer rate determining steps has been proposed. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 613–619, 1998 相似文献
4.
Summary The kinetics of the reaction between nitrous acid and gold(III) in an HCl medium was studied. The reaction was first order with respect to [AuIII] and [HNO2]·H+ and Cl- ions inhibit the rate and alkali metal ions have specific effects on the rate. The reaction appears to involve different gold(III) species, viz. AuCl
inf4
sup–
, AuCl3(OH2) and AuCl3(OH)–, which undergo a two-equivalent reduction to gold(I) leading to the formation of NO
inf2
sup+
which under-goes rapid hydrolysis to give nitric acid. 相似文献
5.
The mechanism of the reactions of methane with the gold(III) complexes [AuClx(H2O)4− x
]3−x
(x = 2, 3, or 4) was studied by the DFT/PBE method with the SBK basis set. High activation barriers obtained for the reactions
of [AuCl4]− and [Au(H2O)Cl3] with methane suggest these reactions cannot proceed under mild conditions. The reaction of the [Au(H2O)2Cl2]+ complex with methane has a rather low energy barrier and proceeds through the formation of an intermediate complex.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 191–201, February, 2006. 相似文献
6.
A reaction of morin with gold(III) in a hydrochloric acid medium has been studied. A redox reaction occurring in the examined
system has been identified. The oxidized form of morin (λmax at 291 nm), being the product of the reaction, has been used as the basis of the spectrophotometric method for the determination
of gold. Gold can be determined in the concentration range of 0.2–12 μg mL−1 (RSD in the range of 0.89–2.38%). The molar absorptivity at 291 nm is equal to 2.02 × 104 L mol−1. cm−1. The developed method was applied to the determination of gold (0.04%) in a cosmetic cream.
Published in Russian in Zhurnal Analiticheskoi Khimii, 2006, Vol. 61, No. 2. pp. 129–133.
The text was submitted by the authors in English. 相似文献
7.
Ajaya Kumar Singh Bhawana Jain Reena Negi Yokraj Katre Surya P. Singh Virender K. Sharma 《Transition Metal Chemistry》2010,35(4):407-414
The kinetics of ruthenium(III) chloride-catalyzed oxidation of glycine by N–bromophthalimide (NBP) was studied in aqueous perchloric acid at 35 °C. The results showed first- and zero-order behavior
with respect to NBP and Gly, respectively. Ru(III) showed a catalytic effect on the reaction which followed first-order kinetics
with respect to [Ru(III)] at a low concentration range and tended to zero order at high concentration range. The rates decreased
with increase in the proton concentration, while chloride positively influenced the rate of the reaction. Two moles of NBP
were required to oxidize one mole of Gly, and the products were identified as phthalimide (NHP), HCN, CO2, and Br−. Neither added NHP nor Br− influenced the reaction rate. Ionic strength and dielectric constant of the medium had no significant effect on the rate.
Activation parameters were determined by studying the reaction at different temperatures. A reaction scheme of the catalytic
oxidation is proposed. 相似文献
8.
Larissa R. Cohen Laura A. Pe?a Anton J. Seidl Janet M. Olsen Jennifer Wekselbaum Patrick E. Hoggard 《Monatshefte für Chemie / Chemical Monthly》2009,34(2):1159-1165
Abstract
Near-UV irradiation of solutions of (Bu4N)AuCl4 in aerated ethanol-stabilized chloroform causes the continuous decomposition of chloroform, as evidenced by the production of many equivalents of HCl and peroxides. At the outset of irradiation, most of the AuCl4 − is reduced to AuCl2 −, but the reduction stops and is reversed. The same experiments done in ethanol-free chloroform cause chloroform decomposition only until the irreversible reduction of the gold is complete. In deoxygenated ethanol-free chloroform, irreversible reduction to AuCl2 − is accompanied by the formation of HCl and CCl4, while the main decomposition products in deoxygenated ethanol-stabilized chloroform are HCl and C2Cl6. It is proposed that, in ethanol-free chloroform, photoreduction of AuCl4 − begins with the concerted elimination of HCl from an association complex of CHCl3 with AuCl4 −, and that ethanol suppresses { \textCHCl3 ·\textAuCl4 - } \{ {\text{CHCl}}_{3} \cdot {\text{AuCl}}_{4}^{ - } \} complex formation, leaving a slower radical process to carry out the photoreduction of AuCl4 − in ethanol-stabilized chloroform. In the presence of oxygen, the radical process causes a build-up of CCl3OOH, which reoxidizes AuCl2 − to AuCl4 − and allows the photodecomposition of CHCl3 to continue indefinitely. 相似文献9.
Adrian Topolski 《Chemical Papers》2011,65(3):389-392
Kinetics of the electron transfer process between citrates and manganese(III) ions has been studied in acidic aqueous solutions.
Acidification of the reaction mixture increased the reaction rate. The reaction is dependent on pH because there are two main
protolytic forms of the Mn(III)-citrate complex in the studied pH range (4.5–6.5). Reduction potentials of Mn(III)/Mn(II)
system in acidic and basic solutions as well as protolytic equilibria play a crucial role in understanding the pH profile
of the studied system. The rate constants for Mn(III)citH and Mn(III)citH2+ species degradation processes are presented (citH3− and citH22− are trivalent and divalent anions of citric acid, citH4, respectively). Protolytic constant (expressed as pK′a) for Mn(III)citH protonation is estimated and discussed. 相似文献
10.
Base hydrolysis of [Cr(ox)2(quin)]3− (where quin2− is N,O-bonded 2,3-pyridinedicarboxylic acid dianion) causes successive ligand dissociation and leads to a formation of a
mixture of oligomeric chromium(III) species, known as chromates(III). The reaction proceeds through [Cr(ox)(quin)(OH)2]3− and [Cr(quin)(OH)4]3− formation. Dissociation of oxalato ligands is preceded by the opening of the Cr-quin chelate-ring at the Cr–N bond. The kinetics
of the chelate-ring opening and the first oxalate dissociation were studied spectrophotometrically, within the lower energy
d–d band region at 0.4–1.0 M NaOH. The pseudo-first-order rate constants (k
obs0 and k
obs1) were calculated using SPECFIT software for an A → B → C reaction pattern. Additionally, kinetics of base hydrolysis of [Cr(ox)(quin)(OH)2]3− and cis-[Cr(ox)2(OH)2]3− were studied. The determined pseudo-first-order rate constants were independent of [OH−]. A mechanism is postulated that the reactive intermediate with the one-end bonded quin ligand, [Cr(ox)2(O-quin)(OH)]4−, formed in the first reaction stage, subsequently undergoes oxalates substitution. Kinetic parameters for the chelate-ring
opening and the first oxalate dissociation were determined. 相似文献
11.
Ewa Kita Hasan Marai Lisiak Michał Miłosz Jasiński Tomasz Drewa 《Transition Metal Chemistry》2010,35(2):177-184
Base hydrolysis of [Cr(ox)2(pda)]3− (where pda is N,O-bonded 2,4- and 2,5- pyridinedicarboxylic acid dianion) causes successive ligand dissociation and leads
to formation of a mixture of oligomeric chromium(III) species, known as chromates(III). The main reaction path proceeds through
[Cr(ox)(pda)(OH)2]3− and [Cr(pda)(OH)4]3− complexes. The kinetics of the first oxalate dissociation was studied spectrophotometrically, within the lower energy d–d
band region, at 0.4–1.0 M NaOH. The character of spectroscopic changes was consistent with a consecutive reaction model, where
the chelate-ring opening and the one-end bonded oxalato liberation are the first and the second reaction stages. The pseudo-first
order rate constants (k
obs0 and k
obs1) were calculated using SPECFIT software for an A → B → C reaction pattern. Additionally, kinetics of base hydrolysis of [Cr(ox)3]3− were studied. The calculated rate constants were independent of [OH
−
]. Kinetic parameters for the chelate-ring opening and the first oxalate dissociation were determined. Effect of the [Cr(ox)2(pda)]3− and [Cr(2,4-pda)3]3− complexes on 3T3 fibroblasts proliferation was studied. The results manifested low cytotoxicity of these complexes, which
makes them promising candidates for dietary supplements. 相似文献
12.
D'Ulivo A Battistini SS Pitzalis E Zamboni R Mester Z Sturgeon RE 《Analytical and bioanalytical chemistry》2007,388(4):783-791
The effect of mM concentrations of K3[Fe(CN)6], Fe(III), Mo(VI), KSCN and KMnO4 on the generation of BiH3 by the reaction of 0.2–10 μg ml−1 Bi(III) with 0.2 M tetrahydroborate(III) at 1 M acidity (HCl or HNO3) was investigated. Chemical vapour generation (CVG) of BiH3 was investigated by atomic absorption spectrometry using a continuous flow reaction system (CF–CVG–AAS) and different mixing
sequences and reagent reaction times. Gas chromatography–mass spectrometry (GC–MS) was employed in batch generation experiments
with NaBD4. In the absence of additives, the formation of Bi0 at high concentrations of Bi(III) caused rollover of calibration curves and limited the linear range to less than 1 μg ml−1 Bi(III). In the presence of additives, the formation of Bi0 was not observed and the linear range was increased to 5 μg ml−1 of Bi(III) while rollover was completely removed. GC–MS experiments indicated that the presence of additives did not affect
the direct transfer of H from boron to bismuth. Experiments with CF–CVG–AAS and different mixing sequences and reagent reaction
times suggest that additives act by preventing the formation of Bi0 through the formation of reaction intermediates which evolve towards the formation of BiH3 at elevated Bi(III)/NaBH4 ratios.
相似文献
13.
The kinetics of the oxidation of promazine and chlorpromazine by hexaimidazolcobalt(III) were studied in the presence of a
large excess of cobalt(III) and H+ ions using u.v.–vis. spectroscopy ([CoIII] = (1–6) × 10−3 m, [ptz] = (2.5–10) × 10−5 m, [H+] = 0.05–0.8 m, I = 1.0 m (H+, Na+, Cl−), T = 333–353 K, l = 1 cm). In each case, the reversible reaction leads to formation of cobalt(II) species and a stable cationic radical. A
linear dependence of the pseudo-first-order rate constant (kobs) on [CoIII] with a non-zero intercept was established for both phenothiazine derivatives. A marked difference in the observed reaction
rate for promazine and chlorpromazine is associated with the difference in its ability to undergo oxidation and is consistent
with a trend in the redox potential changes for these reductants. The activation parameters for reactions studied were determined.
Mechanistic consequences of all the results are discussed. 相似文献
14.
Joanna Wiśniewska 《Transition Metal Chemistry》2007,32(1):107-111
The kinetics of the oxidation of promazine by trisoxalatocobaltate(III) were studied in the presence of a large excess of
the cobalt(III) in tris buffer solution using u.v.–vis spectroscopy ([CoIII] = (0.6 − 2) × 10−3
M, [ptz] = 6 × 10−5
M, pH = 6.6–7.8, I = 0.1 M (NaCl), T = 288−308 K, l = 1 cm). The reaction proceeds via two consecutive reversible steps. In the first step, the reaction leads to formation of cobalt(II) species and a stable cationic
radical. In the second step, cobalt(III) is reduced to cobalt(II) ion and a promazine radical is oxidized to the promazine
5-oxide. Linear dependences of the pseudo-first-order rate constants (k
1 and k
2) on [CoIII] with a non-zero intercept were established for both redox processes. Rates of reactions decreased with increasing concentration
of the H+ ion indicating that the promazine and its radical exist in equilibrium with their deprotonated forms, which are reactive
reducing species. The activation parameters for reactions studied were as follows: ΔH≠ = 44 ± 1 kJ mol−1, ΔS≠ = −100 ± 4 JK−1 mol−1 for the first step and ΔH≠ = 25 ± 1 kJ mol−1, ΔS≠ = −169 ± 4 J K−1 mol−1 for the second step, respectively. Mechanistic consequences of all the results are discussed. 相似文献
15.
Carmen Batista José Daniel Martínez Mary Lorena Araujo Felipe Brito Giuseppe Lubes Mildred Rodríguez Vito Lubes 《Journal of solution chemistry》2011,40(6):944-954
In this paper we present speciation results for the ternary vanadium(III)–dipicolinic acid (H2dipic) systems with the amino acids glycine (Hgly), proline (Hpro), α-alanine (Hα-ala), and β-alanine (Hβ-ala), obtained by means of electromotive forces measurements emf(H) using 3.0 mol⋅dm−3 KCl as the ionic medium and a temperature of 25 °C. The experimental data were analyzed by means of the computational least-squares
program LETAGROP, taking into account hydrolysis of the vanadium(III) cation, the respective stability constants of the binary
complexes, and the acid base reactions of the ligands, which were kept fixed during the analysis. In the vanadium(III)–dipicolinic
acid–glycine system, formation of the ternary [V(Hdipic)(Hgly)]2+, [V(dipic)(Hgly)]+, [V(dipic)(gly)], [V(dipic)(gly)(OH)]− and [V(dipic)(gly)(OH)2]2− was observed; in the case of the vanadium(III)–dipicolinic acid–proline system the ternary complexes [V(Hdipic) (Hpro)]2+, [V(dipic)(Hpro)]+, [V(dipic)(pro)] and [V(dipic)(pro)(OH)]− were observed; in the vanadium(III)–picolinic acid–α-alanine were observed [V(Hdipic)(Hα-ala)]2+, [V(dipic) (Hα-ala)]+, [V(dipic)(αala)], [V(dipic)(α-ala)(OH)]− and [V(dipic)(α-ala)(OH)2]2−; and in the vanadium(III)–dipicolinic acid–β-ala system the complexes [V(dipic) (Hβ-ala)]+, [V(dipic)(β-ala)], [V(dipic)(β-ala)(OH)]− and [V(dipic)(β-ala)(OH)2]2− were observed. Their respective stability constants were determined, and we evaluated values of Δlog 10
K″ in order to understand the relative stability of the ternary complexes compared to the corresponding binary ones. The species
distribution diagrams are briefly discussed as a function of pH. 相似文献
16.
Isaida Shiozawa Giuseppe Lubes Mildred Rodríguez Vito Lubes 《Journal of solution chemistry》2011,40(1):17-25
In this work we present results for the speciation of the ternary complexes formed in the aqueous vanadium(III)–dipicolinic
acid and the amino acids cysteine (H2cys), histidine (Hhis), aspartic acid (H2asp) and glutamic acid (H2glu) systems (25 °C; 3.0 mol⋅dm−3 KCl as ionic medium), determined by means of potentiometric measurements. The potentiometric data were analyzed with the
least-squares program LETAGROP, taking into account the hydrolysis of vanadium(III), the acid-base reactions of the ligands,
and the binary complexes formed. Under the experimental conditions (vanadium(III) concentration = 2–3 mmol⋅dm−3 and vanadium(III): dipicolinic acid: amino acid molar ratio 1:1:1, 1:1:2 and 1:2:1), the following species [V(dipic)(H2asp)]+, [V(dipic)(Hasp)], [V(dipic)(asp)]−, [V(dipic)(asp)(OH)]2−, and [V(dipic)(asp)(OH)2]3− were found in the vanadium(III)–dipicolinic acid–aspartic acid system. In the vanadium(III)–dipicolinic acid–glutamic acid
system [V(Hdipic)(H2glu)]2+, [V(dipic)(H2glu)]+, [V(dipic)(Hglu)], [V(dipic)(Hglu)(OH)]−, and [V(dipic)(Hglu)(OH)2]2− were observed. In the vanadium(III)–dipicolinic acid–cysteine system the complexes [V(dipic)(H2cys)]+, [V(dipic)(Hcys)], [V(dipic)(cys)]−, and [V(dipic)(cys)(OH)]2− were present. And finally, in the vanadium(III)–dipicolinic acid–histidine system the complexes [V(Hdipic)(Hhis)]2+, [V(dipic) (Hhis)]+[\mathrm{V}(\mathrm{dipic}) (\mathrm{Hhis})]^{+}, [V(dipic)(his)], [V(dipic)(his)(OH)]−, and [V(dipic)(his)(OH)2]2− were observed. The stability constants of these complexes were determined. The species distribution diagrams as a function
of pH are briefly discussed. 相似文献
17.
Murugesan Vairalakshmi Veerian Raj Ponnusamy Sami Kasi Rajasekaran 《Transition Metal Chemistry》2011,36(8):875-882
The kinetics of oxidation of phenol and a few ring-substituted phenols by heteropoly 11-tungstophosphovanadate(V), [PVVW11O40]4− (HPA) have been studied spectrophotometrically in aqueous acidic medium containing perchloric acid and also in acetate buffers
of several pH values at 25 °C. EPR and optical studies show that HPA is reduced to the one-electron reduced heteropoly blue
(HPB) [PVIVW11O40]5−. In acetate buffers, the build up and decay of the intermediate biphenoquinone show the generation of phenoxyl radical (ArO·) in the rate-determining step. At constant pH, the reaction shows simple second-order kinetics with first-order dependence
of rate on both [ArOH] and [HPA]. At constant [ArOH], the rate of the reaction increases with increase in pH. The plot of
apparent second-order rate constant, k
2, versus 1/[H+] is linear with finite intercept. This shows that both the undissociated phenol (ArOH) and the phenoxide ion (ArO−) are the reactive species. The ArO−–HPA reaction is the dominant pathway in acetate buffer and it proceeds through the OH− ion triggered sequential proton transfer followed by electron transfer (PT-ET) mechanism. The rate constant for ArO−–HPA reaction, calculated using Marcus theory, agrees fairly well with the experimental value. The reactivity of substituted
phenoxide ions correlates with the Hammett σ+ constants, and ρ value was found to be −4.8. In acidic medium, ArOH is the reactive species. Retardation of rate for the
oxidation of C6H5OD in D2O indicates breaking of the O–H bond in the rate-limiting step. The results of kinetic studies show that the HPA-ArOH reaction
proceeds through a concerted proton-coupled electron transfer mechanism in which water acts as proton acceptor (separated-CPET). 相似文献
18.
A. V. Ivanov V. I. Sergienko A. V. Gerasimenko O. V. Loseva A. S. Zaeva 《Russian Journal of Coordination Chemistry》2010,36(5):353-358
The chemisorption properties of cadmium dibutyldithiocarbamate with respect to [AuCl4]− in 2M HCl solutions are studied. The heterogeneous reaction of gold(III) binding affords the heteropolynuclear compound ([NH{2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4])
n
(I). The molecular and crystal structures of compound I are determined from the X-ray diffraction data. Each of three ions is presented in the structure by two conformers. The irreversible
decomposition of some dibutyldithiocarbamate groups is observed during the chemisorption of gold(III), which noticeably decreases
the efficiency of gold binding with the sorbent studied and its sorption capacity. The study of the thermal properties of
compound I shows that gold(III) is reduced to the metal during thermolysis. 相似文献
19.
An ion-selective electrode (ISE) for measurement of [AuCl4]− anions based on tetradecylammonium tetrachloroaurate(III) in a polyvinyl chloride matrix deposited on a solid graphite-polyvinylchloride
composition was developed. Its characteristics such as stability of the electrode potential, linear region of the electrode
function and its slope, and the limit of detection were determined. The effect of HCl and KCl concentrations on the characteristics
of the ISE were studied to select the optimum measurement conditions. The developed electrode was used to estimate the conditional
solubility product of some soluble compounds containing [AuCl4]−. 相似文献
20.
Wagner José Barreto Sonia Regina Giancoli Barreto Waleria Pickina Silva 《Transition Metal Chemistry》2009,34(6):677-681
The reaction between Fe(III) and dopamine in aqueous solution in the presence of Na2S2O3 was followed through UV–Vis spectroscopy, pH and oxy-reduction potential (Eh) measurements. The formation and quick disappearing
of the complex [Fe(III)HL1−]2+, HL1− = monoprotonated dopamine was observed with or without S2O3
2− at pH 3. An unexpected reaction occurs in presence of thiosulfate forming the stable anion complex [Fe(III)(L2−)2]1−, L2− = dopacatecholate (λ = 580 nm) and the auto-increasing of the pH, from 3 to 7. It was proposed that H+ and molecular oxygen are consumed by free radical thiosulfate formed during the reaction. 相似文献