All Organic Sodium‐Ion Batteries with Na4C8H2O6

Developing organic compounds with multifunctional groups to be used as electrode materials for rechargeable sodium‐ion batteries is very important. The organic tetrasodium salt of 2,5‐dihydroxyterephthalic acid (Na₄DHTPA; Na₄C₈H₂O₆), which was prepared through a green one‐pot method, was investigated at potential windows of 1.6–2.8 V as the positive electrode or 0.1–1.8 V as the negative electrode (vs. Na⁺/Na), each delivering compatible and stable capacities of ca. 180 mAh g^?1 with excellent cycling. A combination of electrochemical, spectroscopic and computational studies revealed that reversible uptake/removal of two Na⁺ ions is associated with the enolate groups at 1.6–2.8 V (Na₂C₈H₂O₆/Na₄C₈H₂O₆) and the carboxylate groups at 0.1–1.8 V (Na₄C₈H₂O₆/Na₆C₈H₂O₆). The use of Na₄C₈H₂O₆ as the initial active materials for both electrodes provided the first example of all‐organic rocking‐chair SIBs with an average operation voltage of 1.8 V and a practical energy density of about 65 Wh kg^?1.     

Stress-strain behaviour of graft copolymers of methyl methacrylate and natural wool fibres

The graft polymerization of methyl methacrylate onto wool, using LiBrK₂S₂O₈ and Na₂S₂O₃H₂O₂ redox systems as initiators, does not change dramatically the stress-strain behaviour of single fibres even for high graft yields. Variations in tensile properties are essentially due to an important radial swelling effect of the deposited polymer accompanied by a moderate increase of internal viscosity and, in the case of Na₂S₂O₃H₂O₂ initiation, to interference from oxidative processes.     

Electron transfer oxidation kinetics of Na2[Mo2O4EDTA] by S2O82− ion in dilute acid medium

Na₂(Mo₂^vO₄EDTA).4H₂O crystals have been prepared in pure form. Kinetics for the oxidation of the compound by S₂O₈²⁻ have been studied spectrophotometrically in dilute sulphuric acid medium. The effects of hydrogen ion concentration, metal ion concentration, S₂O₈²⁻ ion concentration, and temperature on the process have been studied. Rate equations have been derived to explain the experimental observations. On the basis of the observations, suitable mechanisms have been suggested. The kinetic parameters E^*, ΔH^≠, and ΔS^≠ of the process have also been determined. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 269–274, 1997     

Short,Enantiospecific Syntheses of Indolizidines 209B and 209D,and Piclavine A from Diethyl-L-Glutamate

The 1H-pyrrole derivative obtained from diethyl L -glutamate hydrochloride and tetrahydro-2,5-dimethoxyfuran was cyclized with BBr₃ to ethyl (5S)-5,6,7,8-tetrahydro-8-oxoindolizine-5-carboxylate ( 18 ). Catalytic hydrogenation of 18 over Pd/C in AcOH gave ethyl (5S,8aR)-octahydroindolizine-5-carboxylate ( 21 ), whereas hydrogenation over Rh/Al₂O₃ in EtOH/AcOH 99:1 afforded mainly ethyl (5S,8S,8aS)-octahydro-8-hydroxyindolizine-5-carboxylate ( 22 ). By functional-group interconversions, 21 was transformed into piclavine A ( 1 ) and indolizidine 209D ( 2 ). Similarly, (5R,8R,8aS)-octahydro-5-pentylindolizine-8-methanol ( 37 ), the final relay for indolizidine 209B ( 3 ), was obtained from 22 .     

Palladium Nanoparticles Embedded into Graphene Nanosheets: Preparation,Characterization, and Nonenzymatic Electrochemical Detection of H2O2

A novel nonenzymatic H₂O₂ sensor based on a palladium nanoparticles/graphene (Pd‐NPs/GN) hybrid nanostructures composite film modified glassy carbon electrode (GCE) was reported. The composites of graphene (GN) decorated with Pd nanoparticles have been prepared by simultaneously reducing graphite oxide (GO) and K₂PdCl₄ in one pot. The Pd‐NPs were intended to enlarge the interplanar spacing of graphene nanosheets and were well dispersed on the surface or completely embedded into few‐layer GN, which maintain their high surface area and prevent GN from aggregating. XPS analysis indicated that the surface Pd atoms are negatively charged, favoring the reduction process of H₂O₂. Moreover, the Pd‐NPs/GN/GCE could remarkably decrease the overpotential and enhance the electron‐transfer rate due to the good contact between Pd‐NPs and GN sheets, and Pd‐NPs have high catalytical effect for H₂O₂ reduction. Amperometric measurements allow observation of the electrochemical reduction of H₂O₂ at 0.5 V (vs. Ag/AgCl). The H₂O₂ reduction current is linear to its concentration in the range from 1×10^?9 to 2×10^?3 M, and the detection limit was found to be 2×10^?10 M (S/N=3). The as‐prepared nonenzymatic H₂O₂ sensor exhibits excellent repeatability, selectivity and long‐term stability.     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.     

trans‐Di­chloro(1,12‐di­phenyl‐5,8‐dioxa‐2,11‐di­thia­do­decane‐S,S′)pal­ladium(II)

In the title compound, [PdCl₂(C₂₀H₂₆O₂S₂)], the Pd atom has a distorted square‐planar coordination geometry, with Pd—S distances of 2.3121 (18) and 2.3102 (18) Å, Pd—Cl distances of 2.291 (2) and 2.314 (2) Å, and S—Pd—Cl angles of 94.98 (7) and 86.25 (7)°. Upon complexation, an 11‐membered ring is formed by the S—Pd—S linkage in the ligand chain.     

High temperature reactions of titanium(IV) oxide with some alkali persulfates and their decomposition products

The solid state reactions between TiO₂ and Na₂S₂O₈ or K₂S₂O₈ have been investigated using TG, DTG, DTA, IR, and X-ray diffraction studies in the range of 20 to 1000°C.It has been shown that TiO₂ reacts stoichiometrically (1 : 1) with Na₂S₂O₈ in the range of 160 and 220°C forming the complex sodium monoperoxodisulfato—titanium(IV) as characterized by IR and X-ray analysis. The new complex then decomposes into the reactants above 190°C.An exothermic reaction has been observed between TiO₂ and molten K₂S₂O₇ at mole ratio 1:2 respectively and higher, in the range of 280 and 350°C. The IR and X-ray analyses have shown the formation of a complex namely, potassium tetrasulfato titanium(IV) for which the formula and structure have been proposed. This complex decomposes at higher temperatures into K₂SO₄ and a mixed sulfate of potassium and titanium. The mixed sulfate melts at 620°C and decomposes into K₂SO₄, TiO₂, and the gaseous SO₃.On the other hand, Na₂S₂O₈ decomposes in a special mode producing a polymeric product of Na₁₀S₉O₃₂. Decomposition of this species occurs after melting at 560°C into Na₂SO₄ and sulfur oxides. The decomposition reaction has been proved to be catalysed by TiO₂ itself.     

Über das Dreistoffsystem Na2S-Sb2S3-H2O. II

Zusammenfassung Das System Na₂S–Sb₂S₃–H₂O wurde bei 20° untersucht. Folgende Bodenkörper treten dabei auf: Na₂S·9 H₂O (A), Na₃SbS₃·8 H₂O (B), NaSbS₂ (C und C'), Na₂Sb₄S₇·2 H₂O (D) und Sb₂S₃ (E).D bildet in Nachbarschaft gegen C eineMischphase, die sich durch stark gekrümmte, faserartig aufgebaute Kristalle auszeichnet.Mit 8 Abbildungen.I. Mittlg. siehe vorangehende Arbeit.Auszug aus der Dissertation vonR. Fiala, Universität Wien (1949).     

Effect of Antioxidants on Stability of Aqueous Solutions of Selenurea and on Properties of Lead Selenide Films Obtained with These Antioxidants

Spectrophotometric method was used to study the kinetics of the process in which aqueous solutions of selenurea of various compositions are oxidized. Significant differences between the stabilities of selenurea solutions were revealed in relation to the selenurea concentration and also to the acidity, or alkalinity of a medium. It was shown that the stability of selenurea solutions is affected by additives of various antioxidants: sodium sulfite Na₂SO₃, ascorbic acid C₆H₈O₆, hydroxylamine chloride NH₂OH·HCl, hydrazine hydrate N₂H₄·H₂O, and tin chloride SnCl₂·2H₂O. It was found that using a 1 : 1 mixture of antioxidants Na₂SO₃ and C₆H₈O₆ substantially raises their antioxidant activity and stabilizes the aqueous solutions of selenurea during up to five days. A hydro-chemical precipitation in the acetate—ethylenediamine reaction system in the presence of the antioxidants under study was used to obtain lead selenide films of stoichiometric composition with thicknesses of 230?670 nm. With the Na₂SO₃ + C₆H₈O₆, Na₂SO₃, C₆H₈O₆, and SnCl₂ antioxidants used to stabilize selenurea solutions, a tendency is observed toward a decrease in the lattice constants of PbSe films from 6.1531 ± 0.0003 to 6.1367 ± 0.0002 Å, an increase in the share of nanosize particles, and rise in the PbSe energy gap width from 0.78 to 1.0 e V.

     

Thermal reactivity of sodium manganese decavanadates

The hydrates of sodium manganese decavanadates are thermally unstable: Na₄MnV₁₀O₂₈ ·19H₂O decomposes on dehydration to give Mn(VO₃)₂, NaVO₃ and NaV₃O₈, while Na₂Mn₂V₁₀O₂₈ · 20H₂O decomposes to Mn(VO₃)₂, NaVO₃, NaV₃O₈ and NaV₆O₁₅. At a lowern(Na) n(V) molar ratio in the starting compound, a product containing a bronze with a higher vanadium(IV) content is formed. The mixtures of products are stable in the temperature ranges 500–1000°C, and 610–1000°C, respectively.

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Zusammenfassung Hydrate von Natrium-magnesiumdekavanadat sind thermisch instabil. Na₄MnV₁₀O₂₈·19H₂O zersetzt sich durch Dehydratierung in Mn(VO₃)₂, NaVO₃ und NaV₃O₈ und Na₂Mn₂V₁₀O₂₈ · 20H₂O in Mn(VO₃)₂, NaVO₃, NaV₃O₈ und NaV₆O₁₅. Bei einem niedrigerem n(Na)n(V) molarem Verhältnis der Ausgangsverbindungen wird ein Produkt geformt, welches eine Bronze mit einem höherem Vanadium(IV)-gehalt enthält. Das Produktegemisch ist im Temperaturbereich 500°–1000°C bzw. 610°–1000°C thermisch stabil.

     

Addition of polyfluoroalkyl iodides to allyl glycidyl ether

Addition of polyfluoroalkyl iodides to the double bond of allyl glycidyl ether occurred under mild conditions (20–25 °C, MeCN/H₂O, Na₂S₂O₄, NaHCO₃) with retention of the oxirane ring. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1476–1478, August, 2007.     

Study of Some Tungsten-Containing Chemical Modifiers in Graphite-Furnace Atomic Absorption Spectrometry

Abstract

Several chemical modifiers based on tungsten have been evaluated: the individual modifiers W(VI) as WO₃ in aq. 0.2 M NH₃ and W(V) as W in H₂O₂ and the mixed modifiers W(VI)/NH₃ + Pd(II), W(V)/H₂O₂ + Pd(II), and W(V)/H₂O₂ + PO₄ ^3-. High efficiency of thermal stabilization for 18 analyte elements of high and moderate volatility has been demonstrated and possible mechanisms of stabilization are discussed.     

Accelerated chemical degradation of polyacrylamide

The chemical degradation of polyacrylamide(PAM) at low temperature in aqueous medium was initiated by peroxides. The degradation degree of the polymer rose with the reaction time. The degradation degree of PAM depended not only on peroxide characteristic but also on the concentration of polyacrylamide and potassium persulfate, degradation temperature and original molecular weight of PAM. The results showed that the order of degradation degree of PAM in three peroxides is K₂S₂O₈ > K₂S₂O₈ — Na₂S₂O₃ > H₂O₂. The degradation degree of PAM grew as reaction temperature, molecular weight of PAM, concentration of potassium persulfate and PAM increased.     

Oxidation and photooxidation of sulfide and thiosulfate ions catalyzed by transition metal chalcogenides and phthalocyanine complexes

The catalytic and photocatalytic activities of supported cobalt or zinc phthalocyanine complexes, bulk MoS₂, MoS₂ deposited on Al₂O₃, potassium intercalated MoS₂ (K_0.33 H₂O_0.66 MoS₂), CdS and polycrystalline nickel phosphorus trisulfide (NiPS₃) have been investigated in the oxidation of sodium sulfide and Na₂S₂O₃. The phthalocyanine complexes and the metal chalcogenides do not catalyze, in the absence of light, the complete oxidation of the sulfide ion to sulfate ion. The final product of the catalytic oxidation is the formed thiosulfate. No oxidation of Na₂S₂O₃ has been registered in the dark in the presence of any of the catalytic samples. Their activity was enhanced upon irradiation with visible light. Thiosulfate appears to be the final product also of the photooxidation of the sulfide ion catalyzed by metal chalcogenides. They do not catalyze the further photooxidation of Na₂S₂O₃. The only photocatalysts which favour with their presence the oxidation of the sulfide and thiosulfate ions to sulfate ion, are the zinc phthalocyanine complexes. In this case, the photooxidation process involves singlet oxygen.     

Coordination modes of 2-hydroxynicotinic acid in second- and third-row transition metal complexes

The new Pd(II), Pt(II), Re(V), Mo(VI) and W(VI) complexes of 2-hydroxynicotinic acid (H₂nicO), trans-[PdCl(HnicO)(PPh₃)₂]·0.75CH₃CN (1), K[PdCl(HnicO)₂]·H₂O (2), [Pd(HnicO)₂(bipy)] (3), cis-[PtCl(HnicO)(PPh₃)₂]·0.75CH₃OH·0.5H₂O (4), [PtCl(HnicO)(bipy)] (5), cis-[ReOI₂(HnicO)(PPh₃)] (6), Na₂[Mo₂O₆(HnicO)₂]·5H₂O (7), Na₂[Mo₄O₁₂(HnicO)₂]·2H₂O (8) and Na₂[W₂O₆(HnicO)₂]·5H₂O (9) have been prepared. The crystal structures of 1 and 4, were determined by X-ray diffraction and show the HnicO⁻ ligand coordinated to palladium or platinum through the nitrogen atom only. Infrared, Raman, ¹H and ¹³C{¹H} NMR spectroscopic data for the complexes are presented and are in agreement with the crystallographic results.     

Synthesis,characterization and DFT calculations of a Re(V)-thiazolidine-2,4-dione complex

This article presents a combined experimental and computational study of a new oxorhenium(V) complex of thiazolidine-2,4-dione (HTDO). The complex has been synthesized by direct reaction of NH₄ReO₄ with thiazolidine-2,4-dione in the presence of Na₂S₂O₆ as a reducing agent. The complex [ReO(TDO)(H₂O)₃](S₂O₈) has been characterized by spectroscopy (FT-IR, NMR, UV-vis, mass), thermogravimetry, microanalysis, and HPL chromatography. The complex was geometrically optimized by DFT with B3LYP level of theory and satisfactory theoretical–experimental agreement was achieved for analysis of IR and NMR data of the complex. Additional information about binding between rhenium and oxo ligand in the complex has been obtained by NBO analysis. The antibacterial activity of the investigated complex has been tested and evaluated.     

Experimental Study on Demercurization Performance of Wet Flue Gas Desulfurization System

The demercurization performance of wet flue gas desulfurization (WFGD) system was investigated by measuring mercury concentrations at the inlet and outlet of WFGD system with a QM201H mercury analyzer. The selected desulfurizer included NH₃·H₂O, NaOH, Na₂CO₃, Ca(OH)₂ and CaCO₃. The influences of adding oxidant and coagulant such as KMnO₄, Fenton reagent, K₂S₂O₈/CuSO₄ and Na₂S into desulfurization solutions were also studied. The results show that elemental mercury is the main component of gaseous mercury in coal‐fired flue gas, and the proportion of oxidized mercury is less than 36%. Oxidized mercury could be removed by WFGD system efficiently, and the removal efficiency could amount to 81.1%–92.6%. However, the concentration of elemental mercury slightly increased at the outlet of WFGD as a result of its insolubility and re‐emission. Therefore, the removal efficiency of gaseous mercury is only 13.3%–18.3%. The mercury removal efficiency of WFGD system increased with increasing the liquid‐gas ratio. In addition, adding KMnO₄, Fenton reagent, K₂S₂O₈/CuSO₄ and Na₂S into desulfurization solutions could increase the mercury removal efficiency obviously. Various additives have different effects, and Na₂S is demonstrated to be the most efficient, in which a mercury removal efficiency of 67.2% can be reached.     

Radiotracer study of the behaviour of arsenic in the graphite furnace

Summary The behaviour of As(III) and As(V) in the graphite furnace during the individual steps of the temperature program was investigated by means of the radiotracer⁷⁶As. The investigated matrix systems include 1 mol/l HCl, 0.2 mol/l HNO₃, 0.2 mol/l NaCl, urine, human serum and a tetramethylammonium hydroxide solution of hair. Significant stabilization effects can be achieved in the preatomization steps by using Ni, W, Mo, Pd, H₂O₂ as well as the mixtures H₂O₂ + Pd, HNO₃ + Pd and H₂O₂ + Ni as matrix modifiers. In sample solutions containing chloride, stabilization of As(III) is possible only in presence of nitric acid. The experimental conditions for the determination of As in urine, human serum and hair have been optimized.

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Radiotracer-Untersuchung des Verhaltens von Arsen im Graphitofen

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Copper(II) catalyzed cross-dehydrogenative coupling of cyclic benzylic ethers with simple carbonyl compounds by Na2S2O8

Copper(II) catalyzed cross-dehydrogenative coupling of cyclic benzylic ethers with a variety of simple carbonyl compounds mediated by Na₂S₂O₈ is developed. The scope of carbonyl components is broad, including simple aldehydes as well as ketones. The use of Na₂S₂O₈ as the oxidant for the CDC reaction is attractive based on economical and environmental factors.