Anion-exchange behavior of various metals in hydrazoic acid media

The adsorption characteristics for 43 metals on a strongly basic ion-exchange resin Bio-Rad AG1 were examined in 0.5 M hydrazoic acid solution. The distribution coefficients for V(IV), Fe(III), Cu(II), Zn, Se(IV), Mo(VI), Pd(II), Cd, In(III), Rc(VII), Hg(II) and U(VI), which showed very strong adsorption except for Cd, were measured as a function of hydrazoic acid concentration over the range 0.05–0.5 M. Favorable differences in the distribution coefficients allow useful two- and three-component separations such as Co(II)-Fe(III), As(III)-V(IV), Cd-Zn, Cd- Hg(II), Te(IV)-Se(IV), Th-U(VI), Mn(II)-Mo(VI)-Re(VII), to be achieved on a small column.     

The use of the silver reductor in bromide solutions

The reduction of bromide solutions of various metals with the silver (walden) reductor is described. Iron(III) is quantitatively reduced to iron(II) in 0.1–4 M HBr; similarly, copper(II) is reduced to copper(I) in > 1.5 M HBr, and vanadium.(V) to vanadium(IV) and uranium(VI) to uranium(IV) in > 0.3 M HBr. Tin(IV) is only partly reduced to tin(II) below 6M HBr. Reduction of molybdenum(VI) to molybdenum(V) requires heating, whereas reduction of tungsten(VI) is never quantitative. Suitable conditions for the titrations are described.     

The polarography of molybdenum,titanium and niobium in solutions of organic acids

Further work on the polarographic reduction of molybdenum(VI), niobium(V) and titanium(IV) in base electrolytes containing organic acids is reported. A base electrolyte of 0.5 M citric acid-0.025 M sulphuric acid-0.05 M thorium nitrate proved suitable for the determination of molybdenum and titanium in the presence of niobium, tantalum, tungsten and zirconium. A direct polarographic method using this base electrolyte is described for the determination of molybdenum in a niobium base alloy.     

Microanalysis with the aid of ion-exchange resins : Part XX1. Detection of nanogram amounts of titanium(IV) with tiron

A sensitive test for nanogram quantities of titanium(IV) is proposed. A resin spot test technique is applied to the colour reaction of titanium(IV) with tiron. The limit of identification is 26 ng of titanium(IV) (1:1.5·10⁶) after 50 min standing. Vanadium(V), chromium(VI), molybdenum(VI) and uranium(VI) interfered seriously. Iron(III) could be masked with EDTA, and iron(III) and titanium (IV) were detected simultaneously.     

The spectrophotometric determination of vanadium after extraction as vanadium(III) ferronate by tribenzylamine

Vanadium(III) obtained by dithionite reduction of vanadium(V) can be extracted as its ferron complex with tribenzylamine in chloroform from 0.05 M sulphuric acid. Vanadium (0–5 μg ml^-1) is determined spectrophotometrically at 430 nm with a sensitivity of 0.0028 μg V cm^-2. Al(III), Co(II), Ni(II), Fe(II, III), Hg(II), Si(IV), Be(II), Mg(II), Ca(II), Sr(II), Ba(II), Cr(VI, III), W(VI), Zn(II), U(VI), Mn(II). Pb(II), Cu(II), Cd(II) and Th(IV) do not interfere; only Mo(VI), Ti(IV), Zr(IV). Bi(V) and Sn(II) interfere. A single determination takes only 7 min. The extracted complex is V^III (R-3H.TBA)₃ where R = C₉H₄O₄NSI. The method is satisfactory for the determination of vanadium in steels, alum and other samples without preliminary separations.     

Solid-phase extraction of plutonium in various oxidation states from simulated groundwater using N-benzoylphenylhydroxylamine

Solid-phase extraction of plutonium in different individual and mixed oxidation states from simulated groundwater (pH 8.5) was studied. The extraction of plutonium species was carried out in a dynamic mode using DIAPAK C16 cartridges modified by N-benzoylphenylhydroxylamine (BPHA). It was shown that the extent of recovery depends on the oxidation state of plutonium. The extraction of Pu(IV) was at the level of 98–99% regardless of the volume and flow-rate of the sample solution. Pu(V) was extracted by 90–95% and 75–80% from 10- and 100-mL aliquots of the samples, respectively, whereas the extraction of Pu(VI) did not exceed 45–50%. An equimolar mixture of Pu(IV), Pu(V), and Pu(VI) was extracted by 74%. The distribution coefficients (K _d) and kinetic exchange capacities (S) of plutonium in various oxidation states were measured. It was found that during the sorption process, Pu(V) was reduced to Pu(IV) by 80–90% after an hour-long contact with the solid phase. Pu(VI) is reduced to Pu(V) by 34% and to Pu(IV) by 55%. In the case of mixed-valent solution of plutonium, only Pu(V) and Pu(IV) were found in the effluents.     

Spectrophotometric study and extraction of niobium(V) complexes with catechol and its derivatives as ion-pairs with quaternary ammonium ions: Application to the separation of niobium from other refractory metal ions

The reactions of niobium(V) with catechol and several substituted derivatives were studied. Optimal conditions for colour development in the niobium(V)-catechol system are: pH 6.7–8.0, and heating at 85° for at least 6 min; the wavelength of maximal absorption is 365 nm, and the molar absorptivity is 1.02·10⁴. Catechol derivatives require lower temperatures and develop colours with niobium(V) in neutral or slightly acidic solutions. The best of the derivatives studied were 3-methyl-catechol and 4-chlorocatechol. Extraction of the ion-pairs formed between niobium-(V)-catechol and different quaternary ammonium ions, was studied with representative solvents. Similar studies were made on other refractory metal ions, i.e., Ti(IV), V(V), Mo(VI) and W(VI), under the optimal conditions for the reaction with niobium(V). Separations of binary (1:1) mixtures of niobium(V) with Ti(IV), V(V), Mo(VI) or W(VI) at the 5·10^-5M level were shown to be possible under the predicted conditions.     

Microanalysis with the aid of ion exchangers : Detection of nanogram amounts of molybdenum(vi) with tiron

A new sensitive and selective resin spot test for nanogram quantities of molybdenum(Vl) with tiron is proposed. The limit of identification is 8 ng(1:5 · 10⁶) after 1 hour standing. Vanadium(V), chromium(VI), uraniuni(lV), titanium (IV), palladiuin(II), platinum(lV), silver(I) and gold(III) interfere. Uranium(VI) (20 ng 1:2·10⁶) can be detected similarly.     

Extraction and separation of bismuth(III) from steel and bismuth-base alloys

Summary Separation of bismuth(III) from iron(III), molybdenum(VI), vanadium(V), chromium(VI), titanium(IV), antimony(III), lead(II), beryllium(II), uranium(VI), hafnium(IV), indium(III) and zirconium (IV) is achieved by solvent extraction with high molecular weight amines from sodium succinate solution adjusted to suitable pH. Bismuth(III) is stripped from the organic phase and determined spectrophotometrically. The method is shown to be applicable to bismuth alloys.

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Extraktion und Trennung von Wismut(III) aus Stahl und wismuthältigen Legierungen

Zusammenfassung Wismut(III) läßt sich von Fe(III), Mo(VI), V(V), Cr(VI), Ti(IV), Sb(III), Pb(II), Be(II), U(VI), Hf(IV), In(III) und Zr(IV) durch Extraktion mit hochmolekularen Aminen aus Natriumsuccinat bei geeignetem pH trennen. Bi(III) wird dann von der organischen Phase getrennt und spektralphotometrisch bestimmt. Das Verfahren eignet sich für Wismutlegierungen.

     

π-Bis(benzene)chromium(0)-catalyzed oligomerization of perfluoropropylene

In the presence of zerovalent π-bis(benzene)chromium(0) (I), perfluoropropylene (II) was found to undergo oligomerization under very mild conditions to dimers (b.p. 46°, M⁺, 300) and trimers (b.p. 100–102°C, M⁺ - 19, 431) in the ratio of 2.5–3.0 to 1. One mol of metal complex could catalyze the conversion of 50 mol of perfluoropropylene. On the basis of ¹⁹F NMR, the structures of the dimers are III and IV in a ratio of ca. 80/20 and the trimers V and VI; VII and VIII also seemed to be present. V/VI/(VII + VIII) is 80/10/4. In benzene solution, perfluoropropylene was shown not to be catalytically oligomerized by fluoride ion (KF, CrF₂ or (CH₃)₄NF) (nor by monovalent π-dibenzenchromium(I). A possible mechanism of the reaction was proposed.     

The oscillopolarographic determination of uranium and thorium in supporting electrolytes containing cupferron

Uranium(VI and IV) and thorium(IV) give cathodic indentations in supporting electrolytes prepared from 0.1M perchloric acid, 0.5 M ammonium thiocyanate and 5·10^-3M cupferron (solution A) or from 0.1 M succinic-succinate buffer pH 4, 0.1 M sodium chloride, 10^-3M cupferron and 0.05% gelatine (solution B). The uranium indentation on the dE/dt = f(E) curve (Q=0.75 and 0.73) permits its detection at the 3·10^-7M level. The thorium indentation (Q=0.78) permits its detection at the 4·10^-7M level in solution B. Methods for the elimination of interfering ions for the uranium determination are described. In the determination of thorium, Ga(III), Fe(III), Ti(IV) and U(VI) interfere.     

Anthraquinones of the lichenAsahinea chrysantha

From a hexane extract of the dry lichen we have isolated six anthraquinones: chrysophanol (I), islandicin (II), cynodontin (III), emodin (IV), a tetrahydroxymethylanthraquinone (V), and a pentahydroxymethylanthraquinone (VI). The structures of (I) and (IV) were confirmed by direct comparison with authentic samples. The structures of (II) and (III) were established by the aid of UV, IR, PMR, and mass spectra. Pigments (V) and (VI) were isolated from a carbonate extract. Pigment (V): mp > 320°C; UV spectrum (nm) 258, 283, 310, 447, 500, 533; mass spectrum: 286 (M⁺ 100%), 270, 258, 257, 241, 229, 216, 213, 212, 211, 201, 161, 155, 137, 115, 105, 97. Pigment (VI): mp 315°C; UV spectrum (nm): 247, 261, 302, 500, 540, 565, 578; IR spectrum (cm^–1): 1587, 3492; mass spectrum: 302 (M⁺, 100%), 286, 274, 245, 228, and the metastable ions 248.6, 219.1, and 192.5. The positions of the -hydroxyls in the molecules of (V) and (VI) have not been definitively established.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 160–165, March–April, 1980.     

Polarographic analytical determination of Hg(II), Cu(II), Cd(II), As(III), Sb(III), Ti(IV) and U(VI) in the presence of Fe(III)

The analytical determination of Hg(II), Cu(II), Cd(II), As(III), Sb(III), Ti(IV) and U(VI) in the presence of Fe(III) and 1 M H₂SO₄ are investigated using the polarographic technique. The wave corresponding to the reduction of Fe(III) to Fe(II) was found to be completely suppressed by the addition of 1% pyrogallol. Thus, different mixtures of these elements, viz. Hg(II), Cu(II), Cd(II), As(III) and Fe(III)-mixture (A), Cu(II), Cd(II), Sb(III), As(III) and Fe(III)-mixture (B), and Cu(II), Cd(II), Ti(IV), U(VI) and Fe(III)-mixture (C), were quantitatively determined using 1% pyrogallol and 1 M H₂SO₄ as supporting electrolyte. The i₁/c results give excellent correlations in each case, as indicated from the results of leastsquares regression analysis.     

Effect of Mn(II) and Ce(IV) Ions on the Oxidation of Lactic Acid by Chromic Acid

The kinetics and mechanism of lactic acid oxidation in the presence of Mn(II) and Ce(IV) ions by chromic acid were studied spectrophotometrically. The oxidation of lactic acid by Cr(VI) was found to proceed in two measurable steps, both of which gave pyruvic acid as the primary product in the absence of Mn(II). 2Cr(VI)+2CH₃CHOHCOOH → 2CH₃COCOOH+Cr(V)+Cr(III) Cr(V)+CH₃CHOHCOOH → Cr(III)+CH₃COCOOHThe observed kinetics was explained due to the catalytic and inhibitory effects of Mn(II) and Ce(IV) on the lactic acid oxidation by Cr(VI). The reactivity of lactic acid depends upon the experimental conditions. It acts as a two-or three-equivalent reducing agent in the absence or presence of Mn(II). It was examined that Cr(III) products resulting from the direct reduction of Cr(VI) by three-equivalent reducing agents. The oxidation of lactic acid follows the complex order kinetics with respect to [lactic acid]. The activation parameters E_a, ΔH^#, and ΔS^# were calculated and discussed.     

Separation of copper(II) from uranium(VI) and many other elements by cation-exchange chromatography in acetone-hydrobromic acid media: Improved selective separation of copper

Co(II), Ni(II), Mn(II), Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti(IV), V(IV), Zr, Hf, Th, Al, Sc, Y, La, the lanthanides and also U(VI), which accompany copper(II) in hydrochloric acid-acetone mixtures, can be separated from copper by eluting copper(II) with 0.50 M hydrobromic acid in 85% acetone from a column of AG 50W-X8 resin, 200–400 mesh, while all these elements are retained by the column quantitatively. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Some relevant elution curves are presented.     

Study of nucleic acid bases by the DADI method

The DADI spectra of the nucleic acid bases adenine (I), guanine (II), Uracil (III), thymine (IV), cytosine (V), and 5-methylcytosine (VI) have been studied. It has been established that the samples of nucleic acid bases investigated are characterized by a specific pattern of the DADI spectra which reflects the nature of the molecular ion due to the structure of the given base and, in the case of M⁺ for (IV) and (VI) also the tautomeric state. The possibility has been shown of using the information obtained for the quantitative determination of (VI) in a mixture of bases.     

A new spot test for cerium(IV)

Summary A new colour reaction for the detection of cerram(IV) which can be carried out both in a test tube and on a spot plate has been described. The test solution is treated with methylene blue in nitric acid solution (11) to form a rose-red colour. This simple procedure has an advantage over the existing tests in that it is applicable in the presence of oxidising agents like chromium(VI), vanadium(V), nitrate, perchlorate and of coloured ions like copper(II), cobalt(II), nickel(II), chromium(III), iron(III), vanadium(IV), uranium(VI).

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Zusammenfassung Eine neue, sowohl in der Eprouvette wie auf der Tüpfelplatte ausführbare Farbreaktion zum Nachweis von Cer(IV) wurde angegeben. Die Probelösung wird mit salpetersaurer Methylenblaulösung behandelt und gibt eine rosarote Färbung. Die Reaktion hat gegenüber bekannten Tests den Vorteil, in Gegenwart von Oxydationsmitteln wie Cr(VI), V(V), NO₃ ^–, ClO₄ ^– bzw. in Anwesenheit gefärbter Ionen wie Cu(II), Co(II), Ni(II), Cr(III), Fe(III), V(IV) oder U(VI) anwendbar zu sein.

     

Untersuchungen zur anwendung ternärer komplexe in der photometrie—I Die bestimmung des Titan(IV) mit Tiron in gegenwart von äthylendiamintetraessigsäure

Two model systems and three analytical procedures based on them have been investigated analytically and characterized statistically with the aim of evaluating the application of ternary complexes in photometry. From measurements on the systems Ti(IV), Tiron (TiR^8?₃, procedure I), Ti(IV), Tiron, EDTA (TiR^8?₃, procedure II), Ti(IV), Tiron, EDTA [TiO(HY)R^5?, procedure III], the molar absorptivities, standard deviations, coefficients of variation, calibration data, limits of detection and determination have been calculated, and the possible interferences of 45 ions have been examined. Procedure III is shown to be the least sensitive of the three, but to offer a higher selectivity towards titanium in the presence of Cr(III), Cu(II), Fe(III), Mn(II), Mo(VI), Ni(II), U(VI) and W(VI). The reasons for this are discussed, and some suggestions are offered concerning the intended application of ternary complexes.     

Dimerization of electrogenerated Mo(V) in sulphuric acid solutions

The electrochemical behaviour of molybdenum(VI) in sulphuric acid solutions was investigated by cyclic voltammetry. In the reduction of Mo(VI) to Mo(III) a dimerization reaction of Mo(V) is involved; the rate constant for the reaction was estimated to be 2.79×10² M⁻¹ s⁻¹ and the activation energy was ca. 35 kJ mol⁻¹ in 0.1 M H₂O₄. Oxidation of the monomer and dimer Mo(V) species take place at −0.31 and +0.18 V (vs. SCE), respectively.     

Oximidobenzotetronic acid as a reagent for the separation and gravimetric determination of palladium and cobalt

Oximidobenzotetronic acid is recommended for the separation and gravimetric determination of palladium and cobalt An ethanolic solution of the reagent quantitatively precipitates palladium(II) from solutions which are 0.75 N in acid up to pH 5.1, the complex is weighed as Pd(C₉H₅NO₄)₂. Cobalt(II) can be determined in the filtrate after the precipitation of palladium. With 0.5 N acid solutions, no interference was found from Pt(IV), Ir(IV), Rh(III), Ru(III), Os(IV), Au(III), Ag(I), Cu(II), Fe(III), Ni(II), Hg(II). Pb(II), Bi(III), Cd(II), As(V), Se(VI), Te(IV), Mo(VI), Sb(III), Al(III), Cr(III), Zn(II), Ti(IV), Zr(IV). acetate, oxalate, citrate, tartrate, phosphate and fluoride.