High performance liquid chromatographic separation and UV determination of cobalt, copper iron and platinum in pharmaceutical preparations using bis(isovalerylacetone)ethylenediimine as complexing reagent

The reagent bis(isovalerylacetone)ethylenediimine(H₂IVA₂en) has been examined for HPLC separation and UV determination of cobalt, copper, iron and platinum using off-line precolumn derivatization and extraction in chloroform. The complexes of cobalt(II), cobalt(III), iron(II), iron(III) and the reagent have been subsequently separated on a Microsorb C-18 column. The complexes were eluted isocratically using ternary mixtures of methanol/water/acetonitrile. Detection was achieved by UV monitoring. Detection limits for Co(II), Co(III), Fe(II) and Fe(III) were 2.5–5.0 ng/injection, based on 0.5–1.0 g/ml with 5 l/injection. The concentration of cobalt(II) and cobalt(III) in aqueous solution have been determined. The presence of oxovanadium(IV), platinum(II), and nickel(II) did not affect the determinations. The HPLC method developed has been applied to the determination of cobalt, copper, iron and platinum in pharmaceutical preparations at the 30 g/g to 15 mg/g level and the obtained results were compared to those of atomic absorption spectrometry.     

1-Aryl-6-azauracile, 4. Mitt.: Die Synthese des 1-Phenyl-5-[5′-methyl-1′,2′,4′-oxdiazolyl-(3′)]-6-azauracils und einiger seiner Derivate

Zusammenfassung Arylhydrazon-cyanacetylcarbamidsäureäthylester (I) wurde durch Einwirkung einer Na₂CO₃-Lösung auf 1-Aryl-5-cyan-6-azauracile (II)^1,2 cyclisiert. Nitrile (II) wurden durch Addition von Hydroxylamin in entsprechende Amidoxime (III) übergeführt, welche durch Kochen mit Acetanhydrid die zugehörigen 1-Aryl-5-[5-methyl-1,2,4-oxdiazolyl(3)]-6-azauracile (IV) lieferten.

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Aryl hydrazone-cyanoacetylcarbamic acid ethyl esters (I) have been cyclized in Na₂CO₃ soln. yielding 1-aryl-5-cyano-6-azauraciles (II)^1,2. Addition of NH₂OH to the nitriles (II) gave the corresponding amidoximes (III), which by refluxing with Ac₂O were converted to the corresponding 1-aryl-5-[5-methyl-1, 2, 4-oxdiazolyl(3)]-6-azauraciles (IV).

     

4(5)-D-Arabinotetrahydroxybutylimidazoline-2-thione (THBIT), a new reagent for the spectrophotometric determination of palladium

Summary 4(5)-D-Arabinotetrahydroxybutylimidazoline-2-thione, THBIT, is proposed as a new reagent for the spectrophotometric determination of Pd(II). Pd(II) forms 11, 12 and 14 complexes with THBIT. The system conforms to Beer's law up to 5g/ml palladium concentration in aqueous medium (molar absorptivity, 1.99×10⁴ l· mole^–1·cm^–1 at 338 nm). The most serious interference is from Hg(II), Os(VIII), Ru(IV), Cr(VI), V(V) and S₂O₃ ^2–. The method has been used successfully for the determination of palladium in catalysts and synthetic samples.     

Determination of palladium, platinum and gold by first derivative spectrophotometry

Summary The application of first-derivative spectrometry to the simultaneous determination of palladium(II), platinum(IV) and gold(III) is described. Light absorption of stable chlorocomplexes formed in 1 mol/l hydrochloric acid provides the basis of their determinations. A difference in the derivative amplitudes between two first-derivative zero crossing points of one metal A is read, corrected for the contribution of metal B and used for quantitation of metal C. Palladium (0.48–20 g ml^–1), platinum (0.16–24 g ml^–1) and gold (0.32–24 g ml^–1) have been determined with good precision and accuracy without any separations. Results are also presented for the simultaneous determination of the three precious metals in the presence of several major constituents.     

Thermodynamics of substituted rhodanine II: Binary complexes of Th(IV), UO2(II), Ce(III), and La(III) with 3-benzamidorhodanine and its derivatives

Summary Th(IV), UO₂(II), Ce(III) and La(III) chelates with 3-benzamidorhodanine and its derivatives have been investigated potentiometrically in 0.1M KCl and 20% (v/v) ethanol-water medium. The stability of the formed complexes increases in the order Th(IV)>UO₂(II)>Ce(III)>La(III). For the same metal ion, the stability of the chelates is found to increase with decreasing temperature, ionic strength, dielectric constant of the medium and by increasing the electron repelling property of the substituent. The thermodynamic parameters (G, H and S) for complexation are evaluated and discussed. The formation of the complexes has been found to be spontaneous, exothermic and entropically favourable.

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Thermodynamik von substituiertem Rhodanin II: Binäre Komplexe von Th(IV), UO₂(II), Ce(III) und La(III) mit 3-Benzamidorhodanin und seinen Derivaten

Zusammenfassung Th(IV)-, UO₂(II)-, Ce(III)- und La(III)-Chelate mit 3-Benzamidorhodanin und seinen Derivaten wurden in 0.1M KCl und 20% (/) Ethanol-Wasser potentiometrisch untersucht. Die Stabilität der gebildeten Komplexe steigt in der Reihenfolge Th(IV)>UO₂(II)>Ce(III)>La(III). Für ein- und dasselbe Metallion steigt die Stabilität der Chelate mit sinkender Temperatur, Ionenstärke und Dielektrizitätskonstante des Mediums und mit steigender Elektronenabstoßungsfähigkeit des Substituenten. Die thermodynamischen Parameter (G, H und S) für die Komplexbildungsreaktion werden bestimmt und diskutiert. Die Bildung der Komplexe erweist sich als spontan, exotherm und entropisch begünstigt.

     

Crystallization,melting and spherulitic structure of Β-nucleated random propylene copolymers

The characteristics of crystallization, melting and spherulitic growth of a random propylene copolymer (PRC) containing small amount of ethylene were studied in the presence of a selective -nucleating agent (calcium pimelate). It was established that the products of isothermal and non-isothermal crystallization are very rich in -modification but have mixed polymorphic composition. The formation of -modification may be attributed to -transition on the surface of growing -spherulites resulting in -twin-spherulites. During melting of PRC of -modification, the characteristics observed with -nucleated propylene homopolymers, namely, a -recrystallization of recooled samples and separated melting of non-recooled samples (i.e. the melting memory effect), as well as a -recrystallization leading to a perfection of the structure within the -modification, are also demonstrated. The disturbance of regularity of the polymer chain highly reduces the tendency to -crystallization. In contrast to the observations with propylene homopolymers, the growth rate of -modification (G ) is higher than that of -modification (G ) and no critical crossover temperature can be found (T()=413 K) below whichG >G . The experimental results show that a partial disturbance of chain regularity by incorporation of comonomer units considerably reduces the tendency to -crystallization.This research was supported by the National Scientific Research Fund (OTKA), the author is grateful for it. Thanks are due to Professor Géza Bodor for his help in X-ray diffractometric investigations and to Ms. Tünde Lócska for her prudential technical assistance in the optical experiments.     

Transformations of solasodine

Solasodine (I) has been subjected to a number of transformations. The following compounds have been obtained from it by described procedures: 3-acetoxypregna-5,16-dien-20-one (II), 3-acetoxypregn-5-en-20-ol (III), and 3-acetoxypregn-5-en-20-ol (IV). The oxidation of (III) and (IV), the formation of an oxime, and the reduction of the oxime with sodium in ethanol, followed by Hess methylation, has led to 20-dimethylaminopregn-5-en-3-ol (IX) and to 20-dimethylaminopregn-5-en-3-ol (X). From compounds (IX) and (X), by analogy with (III) and (IV) by their oxidation and the preparation of oximes, which were then reduced and methylated, the following were obtained: 3,20-bisdimethylaminopregnane (XVII) and 3,20-bisdimethylaminopregnane (XVIII), and also quaternary salts of the latter.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 370–374, May–June, 1980.     

Calculation of the energy spectrum of surface oxygen on CuO by the interacting bonds method

Using the interacting bonds model a calculation has been made for the energy spectrum of oxygen on the CuO surface. Dissociative adsorption of oxygen can be realized in one and two-center forms with 9.2 and 60.4 kcal/mol, respectively. Intermediate values of the adsorption heats are attributed to oxygen adsorption on induced and biographic defects. The theoretically calculated energy spectrum of adsorbed oxygen is in reasonable agreement with that obtained experimentally from the dependence of isosteric heats of oxygen adsorption on the surface coverage.

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CuO. - 9,2 60,4 / . . .

     

Synthesis,metal-exchange kinetics and X-ray structure of the nickel(II) complex of the diazacyclam ligand 1,3,6,10,12,15-hexa-azatricyclo [13.3.1.16,10]eicosane, [NiL] (ClO4)2

The preparation of the nickel(II) complex of the diazacyclam ligand 1,3,6,10,12,15-hexaazatricyclo [13.3.1.16,10]eicosane (2) by the reaction of the nickel(II) complex of N-(2-aminoethyl)-1,3-diaminopropane with formaldehyde in MeOH solution is described. The crystal structure of [NiL](ClO4)2 has been determined. The nickel atom is four coordinate and planar with Ni-N bond lengths of 1.969(4) and 1.928(3)Å in a centrosymmetric structure. The basic diazacyclam ring system has a trans III configuration with the two additional six-membered rings fused in a chair conformation.The kinetics of the metal exchange:for the nickel complexes (1) and (2) have been studied in detail. Under the experimental conditions employed, with copper(II) in at least a tenfold excess, the reaction is independent of the copper(II) concentration. The copper(II) effectively scavenges the free ligand as the nickel(II) complex dissociates. For the nickel complex (1) k = 2 × 10–4 s–1 at 60°C and H = 126 ± 5 kJmol–1 and S298 = 61 ± 15 JK–1mol–1. For the complex (2), k = 1.8 × 10–4 s–1 at 60°C and H = 99 ± 6 kJmol–1 and S298 = –21 ± 10 JK–1 mol–1.     

Selective Spectrophotometric Determination of Aluminium in the Presence of Beryllium and Lanthanide Cations

A spectrophotometric method for the selective determination of Al(III) in the presence of Be and Ln (lanthanide) cations is proposed. It is based on the selective reaction of SXO (Semi-Xylenol Orange) with Al(III) at pH 2.6. The presence of 8%v/v of 1,2-ethanediol serves to stabilize the chelate formed by heating at 100°C for 5min. 0.5mg each of Be(II), Ce(III), La(III), 4mg of Mn(II), 1.2mg of Pb(II), 1mg of Tl(I), 40mg each of Ca(II) and Mg(II) and 1.9mg of sodium dihydrogen phosphate are tolerable. A ligand buffer of HEDTA-Pb is incorporated to further enhance the selectivity of the color reaction. Under the specified conditions SXO reacts with Al(III) to form a 1:1 chelate. Its molar absorptivity at 526nm was found to be 3.3×10⁴Lmol^–1cm^–1. The linear regression equation for 2–20µg of Al(III) is A=0.04458C+0.0112 (where C stands for the concentration of Al(III), µg per 25mL) and correlation coefficient =0.9988. The RSD at the level of 10µg (n=10) and LOQ were found to be 3.5% and 2µg, respectively.     

Die Reaktion von Ce(III), Th(IV) und U(VI) mit Chinizaringrün und seinem nichtsulfonierten Grundkörper

The reaction of 1,4-(2-sulpho-4-methylanilino)anthraquinone (quinizarin green,QG) and its non-sulphonated derivative (NSQG) with Ce(III), Th(IV), and U(VI) was investigated. Spectrophotometric and conductometric studies were carried out to investigate the stoichiometry of the complexes formed. The studies revealed the formation of 11 and 12 (ML) complexes. The apparent stability constants of the different complexes were determined. The structure of the ligand in the solid chelates was studied by IR spectrophotometry which showed that the chelate formation takes place through the oxygen of the C=O group and the -imino nitrogen.

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Mit 6 Abbildungen     

Studies of vanadium catalysts for sulfur dioxide oxidation by51V-NMR

Studies of the⁵¹V-NMR spectra of a series of industrial catalysts and systems modelling the active catalyst component indicate that the catalyst composition depends on the preparation method and during thermal treatment the support interacts with the active component. The local environment of vanadium is being formed in the process of catalytic reactions.

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⁵¹V , -I-4, , : KVO₃, KVO₃–SiO₂, KVO₃–K₂SO₄ , , . .

     

Thermal equilibrium between vanadyloctaethylporphyrin and hydrogenated porphyrin during the hydrodemetallation process

Hydrogenation of the vanadyloctaethylporphyrin VO(OEP), is a reversible reaction which may occur without a catalyst. The thermodynamic data have been deduced from experiments performed in a batch reactor. Both H^o and S^o are positive; this can be explained by the aromatic character of chlorin, the reaction product. From a kinetic point of view, the rate order relative to H₂ is equal to one.

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VO(OEP), , . . H^o S^o , , . , .

     

MAMT,a new chromogenic reagent for Ru,Rh, Pd,Pt and Au in TLC,and for their evaluation by ring colorimetry

Summary Micro-analytical separations of some platinum metals [Ru(III), Rh(III), Pd(II), Pt(IV), and Au(III)] in mixed solutions of their salts have been carried out by ascending thin layer chromatography on Silica Gel G. 3-Mercapto-4-amino-5-methyl-1,2,4-triazole (MAMT) has been successfully used for the visualisation of the above ions on TLC plates and also for colorimetric evaluation of the chromatographed species by ring colorimetry.MAMT=3-Mercapto-4-amino-5-methyl-1,2,4-triazole     

The nickel reactrode,a metal specific voltammetric electrode

The nickel reactive electrode (reactrode) is a solid bulk-modified composite electrode for the selective voltammetric determination of nickel in aqueous solutions. This reactrode offers the possibility for nickel determination in the range from 0.7 ng/ml to 1 g/ml. The 3 detection limit is 0.7 ng/ml.     

Triterpene glycosides and their genins fromThalictrum foetidum. V. Structure of cyclofoetoside B

A new glycoside (cyclofoetoside B) (I) has been isolated from the epigeal part of the plantThalictrum foetidum L. (Ranunculaceae). On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that cyclofoetoside B is 24S-cycloartane-3, 16, 24, 25, 29-pentaol 3-O--L-arabinopyranoside 16-O-[O--L-rhamnopyranoside-(1 6)--D-glucopyranoside], C₄₇-H₈₀O₁₇, mp 194–197°C (methanol); [] _D ²⁴ +15.7 ± 2° (c 0.88; pyridine). The enzymatic hydrolysis of (I) has yielded cyclofoetigenin B (III), 24S-cycloartane-3,16,24,25,29-pentaol 16-O--D-glucopyranoside, (IV), C₃₆H₆₂O₁₀, mp 223–225°C (acetone), [] _D ²⁴ +37 ± 2° (c 0.97; methanol) and 24S-cycloartane-3,16,24,25,29-pentaol 16-O-[O--L-rhamnopyranosyl-(1 6)--D-glucopyranoside, C₄₂H₇₂O₁₄, mp 229–231°C (methanol), [] _D ³⁰ +41 ± 2° (c 0.7; methanol). Details of the IR and¹H and¹³C NMR spectra of the compounds are given.Irkutsk Institute of Organic Chemistry, Academy of Sciences of the USSR. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Trashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 341–345, May–June, 1986.     

Mechanism of oxidation of molybdovanadophosphoric heteropoly blues by molecular oxygen. Trivanadium heteropoly blue

The oxidation of a heteropoly blue (HPB) of the composition Na_xH_9-xPMo₉V₃O₄₀ with molecular oxygen has been studied by the method of catalytic vanadyl oxidation. It is shown that the reduction of an oxygen molecule requires the addition of a fourth atom of V(IV) in the form of a vanadyl ion to the heteropoly anion.

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: Na_xH_9-xPMo₉V₃O₄₀. , V(IV), .

     

Structure of lophopterol

Summary When suberosin is allowed to stand in chloroform at room temperature with access of atmospheric oxygen, photooxidation takes place with the formation of at least three substances: (II), C₁₅H₁₆O₄, mp 172–174°C; (III), C₁₅H₁₆O₅, mp 184–185°C; and (IV).It has been established by NMR and mass spectroscopy and also by their chemical properties, that (II) is 6-(3-hydroxyisopent-2-en-1-yl)-7-methoxycoumarin (trans-suberenol) and (III) is 6-(1,2-epoxy-3-hydroxyisopentyl)-7-methoxycoumarin (lophopterol). The nature of (IV) has not yet been determined.It has been shown experimentally that no such oxidation takes place with an isomer of (I) — osthole (IX). A scheme for the biogenesis of coumarins in the organism of the plant investigated has been put forward.Leningrad Sanitary-Hygienic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 131–133, March–April, 1975.