Anomalous solvent extraction behavior of astatine

We studied the solvent extraction behavior of astatine and found the anomalous behavior of this element similar to radioiodine. Astatine was extracted into CS₂ from acidic solution over a wide range of carrier iodine concentration. The distribution ratios of astatine were determined by measuring the -ray from 210 At with a Nal(TI) detector. A drastic change was observed around at 10^–4 mol/l as in the case of 131 I. This tendency is well explained by the kinematics of the chemical reactions concemed.     

Effect of the specific activity of the tracer on rat luteinizing hormone radioimmunoassay

Rat luteinizing hormone /LH/ was labelled with¹²⁵I by the Chloramine T method.¹²⁵I-LH, used as tracer in radioimmunoassay, was separated from the labelling reaction mixture by gel filtration. By using the proper protein/radioiodine ratio in the labelling reaction mixture the specific activity of¹²⁵I-LH was adjusted to 2.5–20.5 MBq g^–1. The influence of the specific activity on the assay parameters as well as on the tracer stability was investigated.     

The mechanism of indium/III/ extraction by trilaurylamine hydrochloride

The extraction behaviour of In/III/ from HCl solutions by trilaurylamine has been described. The dependence of extraction on acidity, salting agent, metal and extractant concentrations, was investigated. The proposed extraction mechanism, from loading data and slope analyses, proved that besides the known 21 complex /TLAH⁺ InCl ₄ ^– . TLAH⁺Cl^–/, the so far unknown 31 complex TLAH⁺InCl ₄ ^– . /TLAH⁺Cl^–/ is formed too.     

Indikation der Sulfat-F?llungstitration mit adsorptionspolarisierten Elektroden

Summary The indication of the sulphate precipitation-titration using adsorption-polarized electrodes (APE) has been maximized. Large differences in quality of the two electrode surfaces produce broad signals. Suitable preparation of the electrode leads to less defective surfaces. Sharp signals result when the platinum black is electrodeposited at 1.4 V followed by oxidation under the same conditions. Addition of lead-, copper- and mercury-salts to the plating solution increases the surface of the deposits, whereas deposits containing Fe are smoother and lead to sharp peaks.Adsorption as well as coprecipitation of oxoanions cause interference. SeO ₄ ^2– and VO ₃ ^– does not interfere with the determination up to a molar ratio of sulphate to oxoanion of 7.51 and 51 resp., whereas a molar ratio up to 25:1 of CrO ₄ ^2– , MoO ₄ ^2– , WO ₄ ^2– and AsO ₃ sulphate can be tolerated. The influence of IOO ₄ ^2– is negligible. Furthermore, the determination of MoO ₄ ^2– and WO ₄ ^2– was found to be possible by titration using APE-indication.     

Transition metal compounds of the purinic isomer allopurinol. Part 1

Summary The synthesis, spectral and magnetic properties of a series of new compounds of Co^II, Ni^II and Cu^II with the purinic isomer allopurinol (L) are reported. The counterions employed were Cl^–, Br^–, NO ₃ ^– , SO ₄ ^2– , ClO ₄ ^– and MeCO ₂ ^– . The metal:ligand stoichiometries found for the compounds range from 11 to 13. Allopurinol exhibits two classes of coordination behaviour: neutral monodentate (M^II=Co, Ni and Cu; X^–=Cl or Br) and monoanionic bidentate for the compound [CuL(OH)]_n. The latter was obtained when the counterion used in the syntheses was NO ₃ ^– , SO ₄ ^2– , ClO ₄ ^– or MeCO ₂ ^– . The coordination behaviour of theN-pyrazolic ring atoms may relate to the interaction mode of this heterocyclic fragment with the xanthine oxidase metalloenzyme.     

Determination of ratios of sulfate to bisulfate ions in aqueous solutions by Raman spectroscopy

Raman spectra are presented for aqueous ammonium bisulfate and zinc sulfate-sulfuric acid solutions over a wide range of concentration and from 20 to 85°C. The heights of the 980 cm ^–1 (primarily SO ₄ ^–2 ) and 1053 cm ^–1 (primarily HSO ₄ ^– ) bands are correlated with the pH of the solutions. The ratio of the species SO ₄ ^–2 and HSO ₄ ^– can be obtained from the ratio of scattering intensities at 980 and 1053 cm ^–1 . The H obtained from plots of the log of the concentration products versus 1/T is –37±5 kJ-mol ^–1 for ammonium bisulfate solutions and –48±4kJ-mol ^–1 for the ZnSO ₄ -H ₂ SO ₄ solutions. This compares to –22 kJ-mol ^–1 for the H of bisulfate ion dissociation as obtained from thermodynamic equilibrium constants.     

Complexes of tri- and tetra-protonated forms of 1,4,8,12-tetraazacyclopentadecane with chloride,nitrate, iodate,and sulfate ions in aqueous media: I. Formation constants,thermodynamic properties,and bonding mechanisms

Complexation stoichiometries and formation constants of tri- and tetra-protonated forms of 1,4,8,12-tetraazacyclopentadecane with NO ₃ ^– , Cl^–, IO ₃ ^– and SO ₄ ^2– ions are determined by pH potentiometric and¹³C NMR spectrometric measurements. Estimates of H and S are obtained from the values of the temperature dependent formation constants and acid dissociation constants. All four anions form only 1 : 1 complexes with the triprotonated amine species. NO ₃ ^– and Cl^– form 1 : 1 complexes only with the tetraprotonated amine, while IO ₃ ^– and SO ₄ ^2– form both 1 : 1 and 2 : 1 complexes. The complexation behavior is interpreted in terms of solvation and internal hydrogen bonding interactions.     

Separation of cerium and europium by extraction with tributyl phosphate and di(2-ethylhexyl)phosphoric acid in n-alkane from nitrate solutions

The following extraction systems have been studied: (Ce³⁺+Eu³⁺) (NO₃)-(EDTA, DCTA, DTPA)/TBP in n-alkane and (Ce³⁺+Eu³⁺)(NO₃)/DEHPA in n-alkane at concentration ratios as follows: [Ce³⁺]=trace –1 mol·dm^–3, [Eu³⁺]=trace –0.1 mol·dm^–3. [TBP]=(0.183–1.83) mol·dm^–3, [DEHPA]=(5·10^–3–0.1) mol·dm^–3, [(H, Na)NO₃]=(0.1–6) mol·dm^–3, [Eu³⁺]: [EDTA, DCTA, DTPA]=11–110. The initial concentration of Eu³⁺ in aqueous phase in the extraction system containing a mixture of Ce³⁺ and Eu³⁺ was trace, 1% and 10% compared with the Ce³⁺ concentration. The distribution of the elements between the phases was observed radiometrically using¹⁴¹Ce,¹⁵²Eu and¹⁵⁴Eu. The results are documented by the distribution ratios D_Ce, D_Eu and separation factor =D_Eu/D_Ce as functions of variable parameters of the systems.     

Structure,vibrational spectra,and energetic stability of LnX<Stack><Subscript>4</Subscript><Superscript>−</Superscript></Stack> ions (Ln=La,Lu; X=F,Cl, Br,I)

Molecular structure and properties of La and Lu tetrahalide ions LnX ₄ ^– ) are studied by the configuration interaction singles-and-doubles method augmented with quadruple excitation correction (CISD+Q) and by the fourth-order Möller-Plesset perturbation theory with account for single, double, triple, and quadruple excitations (SDTQ-MP4). The atomic inner shells are described by Stevens relativistic effective core potentials. Valence basis sets are augmented with diffuse s-, p-, and polarization d-, f-, and g-functions. The equilibrium configuration of nuclei in LnX ₄ ^– ions was found to be tetrahedral. The equilibrium internuclear distances, quadratic force constants, vibrational frequencies, and IR intensities of LnX ₄ ^– ions are compared with the corresponding parameters of La and Lu trihalide molecules (LnX₃), calculated within the same approximations. Regularities in the behavior of molecular parameters on going along the LnF ₄ ^– LnCl ₄ ^– LnBr ₄ ^– LnI ₄ ^– series and from La compounds to Lu compounds are revealed. Heights of the energy barriers to the LnX ₄ ^– inversion through the square planar structures (T _d D _4h T _d ) are evaluated: 100–110 and 130–150 kJ/mol for LaX ₄ ^– and LuX ₄ ^– , respectively. Enthalpies of dissociation reactions LnX ₄ ^– LnX₃+X^– are calculated and the results obtained are compared with the available experimental data.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 218–228.Original Russian Text Copyright © 2005 by Solomonik, Smirnov, Mileyev.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Photometric Determination of Zirconium with Semimethylthymol Blue

The complexation of zirconium(IV) with Semimethylthymol Blue (H₄L) was studied by spectrophotometry. The formation of the (ZrOH)₂(H₂L)²⁺ ₂ complex with log = 20.68 ± 0.12 and ₅₆₅ = (7.26 ± 0.02) × 10⁴ was revealed by the isomolar series and molar ratio methods. A simple, reliable, and sensitive method was developed for the photometric determination of zirconium. The calibration plot is linear in the concentration range of 10^–6–10^–5 M zirconium. In a sample of frit 24–70 containing 5.7% ZrO₂, 5.44 ± 0.15% ZrO₂ was found.     

The viscoelasticity of spinnable solutions of alkyltrimethylammonium salicylates

The viscoelasticity has been measured for aqueous solutions of tetradecyl-and hexadecyltrimethylammonium salicylates (C₁₄TASal, C₁₆TASal). The aqueous solutions of C₁₄TASal without salt displayed the gel-like behavior at 10.0×10^–2 g cm^–3, but those more dilute than 3.2×10^–2 g cm^–3 presented the viscoelasticity similar to that of a Maxwell liquid. The Maxwell-like behavior was converted to the polymer-like one on the addition of (0.1–0.2) M NaBr or (0.02–0.2) M NaSal. The gel-like viscoelasticity can be connected with the spinnability of cohesive fracture failure, and the Maxwell-like and polymer-like viscoelasticities are concerned with the spinnability of ductile failure. The gel-like and Maxwell-like viscoelasticities originate in the pseudo-network formed by the pseudo-linkages between rodlike micelles, while the polymer-like viscoelasticity is caused by the entanglement of long rodlike micelles in semidilute and concentrated solutions. The aqueous solutions of C₁₆TASal behaved very similar to those of C₁₄TASal.     

Alpha-recoil atoms of plutonium in the environment

The -recoil effect of²³⁹Pu has been observed in environmental samples and theN ₅ ^P /N₅ ratio in these samples has been calculated. This ratio in atmospheric samples is in the range between 10^–5 and 10^–4 (atom/atom). For other contemporary terrestrial samples it is in the range between 10^–7 and 10^–6 (atom/atom), while that of uranium mineral is about 10^–10 (atom/atom). The results further explain the radioactive fallout contamination of our environment by uranium and plutonium isotopes.     

Multinuclear macromolecule metal complexes 2. Preparation and characterization of Prussian blue and its analogs bonded to pofy(vinylamine hydrochloride)

Prussian blue and its analogs bonded to poly(vinylamine hydrochloride) (PVAm · HCl) containing Fe^II or Fe^III and M²⁺ (M=Fe, Co, Cu) in a 11 molar ratio were obtained by the reaction of [Fe(CN)₆] ^n– (n=3,4) with M²⁺ ion-PVAm · HCl mixture in aqueous solution. Under a limited polymer concentration (T_VAm/T_Fe over 10), these polymer complexes thus obtained were stable and soluble in water. By casting these solutions, colored films can be produced. The formation of Prussian blue and its analogs bonded to PVAm · HCl was also investigated by the Benesi-Hildebrand method. The molar extinction coefficients of intervalence charge transfer (Fe^IIFe^III, Co^IIFe^III, Fe^IICu^II) band for MFe(CN)₆]^(n–2)– bound to PVAm · HCl (M=Fe, Co, Cu) were found to be 10,100–9601 · mol^–1 · cm^–1 at 25 C. The formation constants were found to be in the range of 10⁷ to 10¹⁰ M^–1. The changes of enthalpy (H) and entropy (S) were found to be in the range of –10.4 to –22.5 kJ · mol^–1 and 5.7 to 52.9 J · K^–1 mol^–1 respectively, at 25C.     

Kinetics and mechanism of the reaction between bis 4-(2-pyridylazo)resorcinol ferrate(III) complex and cyanide ion

Summary Kinetics and mechanism of formation of a 113 mixed cyano-complex from [Fe^III (Par)₂]^– (where Par represents 4-(2-pyridylazo)resorcional) and cyanide ion has been studied spectrophotometrically at 720 nm [_max=Fe^(III)(Par) ₂ ^– ], pH=10.0±0.02, temp=25±0.1°C and 1=0.1 M (NaClO₄). The order with respect to cyanidevaries from one to two at high and low cyanide concentrations respectively. The rate constants for respective reactions are k₁=10.8±0.6×10^–2 M^–1 s^–1, k₂=7.7±0.5 M^–2 s^–1. The reverse reaction does not occur at a measurable rate even in presence of large excess of par. These observations suggest that Fe^III (Par) ₂ ^– forms a mixed complex, [FePar(CN)₃]^2-, in presence of an excess of cyanide ions. A three-step mechanism consistent with these results is proposed. The activation parameters for the reaction have been derived and used to support the proposed mechanism. The effect of ionic strength lends further support to the mechanism.     

The first ionization constant from 25 to 200°C and 2000 bar for orthophosphoric acid

The ionization constant of orthophosphoric acid, determined by conductivity measurements, decreased from 7.11×10^–3 at 25°C to 6.2×10^–4 mol-kg^–1 at 200°C. The pressure effect to 2000 bar was also measured and the ratio K₂₀₀₀/K₁ is 2.7 at 25°C and 3.7 at 200°C. The standard partial molar volume change for the ionization at 1 bar, , changes from –16.1 at 25°C to –33.3 cm³-mol^–1 at 200°C. The partial molar compressibility change for the ionization, , varies from –3.8×10^–3 to –8.3×10^–3 cm³-mol^–1 bar^–1 over the same temperature range.     

An independent kinetic and mechanistic study of the secondary reactions in the substitution of [FeL(OH)](n−2)− (L= triethylenetetraaminehexaacetic acid) by cyanide ions

Summary The kinetics of reaction between [Fe(CN)₅OH]^3– and CN^– have been investigated spectrophotometrically at pH=11.00, I=0.25 M(NaClO₄) and temp.=25.0°C by disappearance of the absorption peak at 395 nm. The rate data for this reaction followed first order kinetics in both [Fe(CN)₅OH^3–] and [CN^–]. The second order rate constant (k_f) was found to be (3.44±0.08)×10^–3 M^–1 s^–1. The pH dependence of the reaction was also investigated in the range 9–12. The activation parameters were found to be H=36.4kJ mol^–1 and S=–168JK^–1 mol^–1.The reaction between [Fe(CN)₆]^3– and TTHA^6– (TTHA=triethylenetetraaminehexaacetic acid) has also been followed spectrophotometrically at 420 nm, pH=11.00, I=0.1M (NaClO₄) and temp.=25.0°C. This reaction also followed first order kinetics in both [Fe(CN) ₆ ^3– ] and [TTHA^6–]. The second order rate constant (k_f) was found to be (3.74±0.21)×10^–2 M^–1 s^–1. The rate of reaction was found to increase with pH in the range 9–11.5. The different reactive species of TTHA (L) are H₂L^4– HL^5– and L^6–. The rate constants for these species have been calculated and the pH profile is explained. The values of the activation parameters were found to be H= 30.9 kJmol^–1 and S=–167JK^–1 mol^–1. Electron transfer from [Fe(CN)₆]^3– to the substrate followed by decomposition of the latter is proposed. The oxidation products of TTHA have been investigated by g.l.c.     

Determination of sulphate in natural water by flow-injection analysis

Summary Sulphate was determined in natural water samples by flow-injection analysis using dimethylsulphonazo-III as reagent. The interference by Ca was eliminated by a cation-exchanger column inserted directly after the sample injection valve. In order to ensure high sensitivity and reproducibility it was necessary to saturate the carrier solution with barium sulphate and to fill the reaction coil with ethanol-water (11) when not in use. Standard deviations were 0.94–1.2% for 6–10mg/l sulphate. The limit of detection was about 0.2mg/l. The calibration graph was linear up to 14mg/l Mg²⁺, NH ₄ ⁺ , Na⁺, K⁺, Cl^–, NO ₃ ^– , PO ₄ ^3– , HCO ₃ ^– and SiO ₃ ^2– did not interfere in the normally occurring concentrations.

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Sulfatbestimmung in natürlichem Wasser durch Flow-Injection-Analyse

Zusammenfassung Als Reagens dient Dimethylsulfonazo-III. Die Störung durch Calcium bei dieser Bestimmung wird durch eine Kationenaustauschersäule eliminiert, die direkt nach dem Probeinjektions-Ventil angeordnet ist. Zur Erhöhung der Empfindlichkeit und Reproduzierbarkeit ist es notwendig, die Trägerlösung mit Bariumsulfat zu sättigen sowie bei Nichtbenutzung des Systems den Reaktionsteil mit Ethanol-Wasser (11) zu füllen. Mit dem so modifizierten Verfahren ergaben sich Standardabweichungen von 0,94–1,2% für 6–10 mg/l Sulfat, die Nachweisgrenze liegt bei 0,2 mg/l. Die Eichkurve ist bis 14 mg/l linear. Mg²⁺, NH ₄ ⁺ , Na⁺, K⁺, Cl^–, NO ₃ ^– , PO ₄ ^3– , HCO ₃ ^– und SiO ₃ ^2– stören in den normalerweise vorkommenden Konzentrationen nicht.

     

Pionic X-ray intensity ratios in chromium compounds

Pionic X-ray intensity ratios in chromium compounds were compared with those from muonic X-rays. The ratios were found depending on the ^– capture ratio as on ^– capture. The difference of the ratios between Cr/H₂O/₆Cl₃ and CrCl₃ was attributed to the formation of pseudoneutron ^– by interaction of hydrogenic protons during passage of a pion in the hydrated compound.     

1:1 Molybdenum(VI) citric acid complexes

Summary The complexes obtained by crystallisation from an aqueous solution of molybdate and citric acid (H₄cit) at pH 4–8 have Mo:cit ratio 11. The new complexes have been characterised by a variety of methods in the solid state and in solution. On this basis two dimeric species, [(MoO₂)₂O(citH)₂]^4– and [(MoO₂)₂O(cit)₂]^6–, and a monomeric species [MoO₃(cit)OH₂]^4– are proposed.     

Kinetics and mechanism of the reaction between bis 4-(2-pyridylazo) resorcinol ferrate(II) complex and cyanide ion

Summary Cyanide ion reacts with [Fe(Par)₂]^2–,i.e. Par=4-(2-pyridylazo)resorcinol to form a 113 mixed cyanocomplex. The reaction has been studied spectrophotometrically at 720 nm _max, pH=11.5±0.02, and I=0.1 M (NaClO₄) at 25±0.1°C. The order with respect to cyanide varies from one to two at high and low cyanide concentrations respectively. The rate constants for respective reactions are k₁=(6.1±0.3)×10^–2 M^–1 s^–1, k₂=(12.6±1.0) M^–2 s^–1. The reverse reaction does not occur at a measurable rate even in presence of a large excess of Par. These observations suggest that [Fe(Par)₂]^2– forms a mixed [FePar(CN)₃]^3– complex in presence of an excess of cyanide ion. The activation parameters for the reaction have been calculated and used to support a three step mechanism consistent with these results. The effect of ionic strength tends further support to the mechanism.