Solvent extraction and spectrophotometric determination of uranium (VI)

Summary Solvent extraction of uranium-sodium diethyldithiocarbamate with ethylmethyl ketone and separation from titanium, zirconium, thorium, lanthanum and cerium has been described. It has been found that 11.75 to 47.00 mg of uranium can be extracted from a binary mixture containing 4.78 to 19.04 mg of titanium, 9.12 to 36.48 mg of zirconium, 116.0 to 460.0 mg of thorium, 6.95 to 27.8 mg of lanthanum or 7.06 to 28.24 mg of cerium at pH 3.0. The pH range between which the separations may be carried out successfully is 2.0 to 3.5. The following cations interfere in the separations: Cu^II, Fe^III, Co^II, Bi^III, Ni^II, Cr^VI, Te^IV, Se^IV, Ag^I, Hg^II, As^III, Sn^IV, Pb^IV, Cd^II, Mo^VI, Mn^II, V^V, Zn^II, In^III, Tl^I, W^VI, Os^VIII and Nb^V.

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Zusammenfassung Uran kann durch Extraktion als Diäthyldithiocarbamidat mit Methyläthylketon von Ti, Zr, Th, La oder Ce getrennt werden. Der günstigste pH-Bereich liegt zwischen 2,0 und 3,5. Die Trennungen wurden mit folgenden Mengen durchgeführt: U (11,75–47,00 mg); Ti (4,78 bis 19,04 mg), Zr (9,12–36,48 mg) Th (116,0–460,0 mg), La (6,95–27,8 mg), Ce (7,06–28,24 mg). Folgende Ionen verursachen Störungen: Cu^II, Fe^III, Co^II, Bi^III, Ni^II, Cr^VI, Te^IV, Se^IV, Ag^I, Hg^II, As^III, Sn^IV, Pb^IV, Cd^II, Mo^VI, Mn^II, V^VI, Zn^II, In^III, Tl^I, W^VI, Os^VIII sowie Nb^V.

     

Chromatographic and electrophoretic determination of thioamides based on thiazole, 1,3,4-thiadiazole, 1,2,4-triazole,and tetrazole

A procedure was developed for the determination of the following thioamides based on thiazole, 1,3,4-thiadiazole, 1,2,4-triazole, and tetrazole: 2-mercaptothiazole (I), 2-mercapto-1,3,4-thiadiazole (II), 2-mercapto-5-methyl-1,3,4-thiadiazole (III), 3-mercapto-1,2,4-triazole (IV), 3-mercapto-4-methyl-1,2,4-triazole (V), and 5-mercapto-1-methyltetrazole (VI). The determination was performed by reversed-phase HPLC on a column (150 × 4 mm) packed with Diaspher-110-C18 (5 μm) using elution with an acetonitrile-acetate buffer solution (pH 4.70) mixture (5: 95). Detection was performed at the light absorption maximums of compounds I (320 nm), II (305 nm), III (310 nm), IV (260 nm), V (254 nm), and VI (245 nm). The calibration graphs were linear over the following concentration ranges (μg/mL): 0.47–11.72 (I), 0.47–11.82 (II), 0.53–13.22 (III), 0.40–10.11 (IV), 0.46–11.52 (V), and 0.46–11.62 (VI). The limits of detection were 0.45, 0.43, 0.50, 0.37, 0.41, and 0.42 μg/mL for compounds I–VI, respectively. Conditions for the separation of a mixture of compounds I and III–V and for the quantitative determination of compounds I–VI by capillary zone electrophoresis (CZE) were optimized. CZE was performed on a quartz capillary of size 60 cm (effective length of 50 cm) × 75 μm at a voltage of 20 kV with a borate buffer solution (pH 9.18). The procedure allowed us to evaluate the concentrations of substances in the ranges of 1.17–93.75 (I), 1.18–94.54 (II), 1.32–105.76 (III), 1.01–101.13 (IV) 1.15–115.16 (V), and 1.16–116.15 (VI) μg/mL with the detection limits of 1.10, 1.11, 1.20, 0.96, 1.01, and 1.02 μg/mL for compounds I–VI, respectively.     

Co(II), Ni(II), and Cu(II) Complexation with Isatin Aminoguanisone and Nitroaminoguanisone

New complexes of bivalent Co, Ni, and Cu with isatin aminoguanisone (HL) and nitroaminoguanisone (HL¹) of the composition ([Co(HL)₂]Cl₂ (I), [Ni(HL)₂]Cl₂ (II), [Cu(L)Cl] (III), [Co(L¹)₂] (IV), [Ni(L¹)₂] (V), and [Cu(L¹)₂] (VI) are synthesized. Their molecular conductivities and effective magnetic moments are measured and thermal stabilities are studied. The type of the ligand coordination in I–VI is proposed on the basis of IR data. The summary of physicochemical data for I–VI and the energy calculations for their molecules by the molecular mechanics method made it possible to establish stoichiometry of the coordination polyhedra of the complexes.     

Synthesis and Structures of Tetra- and Triarylantimony Oximates

Tetraphenylantimony acetophenoneoximate (I) and tetra-n-tolylantimony 3-nitrobenzaloximate (II) were synthesized by reacting pentaarylantimony with oxime or triarylantimony dioximate in toluene. Tri-n-tolylantimony bis(acetophenoneoximate) (III) and triphenylantimony bis(cyclohexanoneoximate) (IV) were synthesized by reacting triarylantimony with oxime and hydrogen peroxide. The structures of compounds I–IV were determined using X-ray diffraction analysis. The antimony atoms in I–IV are coordinated to the axial oxime groups to form a distorted trigonal bipyramid. The Sb–C(Ph) and Sb–O bond lengths and Sb...N intramolecular contacts in structures I and II lie within 2.114–2.135, 2.137–2.154, and 2.857–2.871 Å, respectively; the respective values in structures III and IV are 2.097–2.112, 2.058–2.080, and 2.779–2.874 Å.     

Interaction of Alkyl Radicals with Dihydric Phenol Derivatives in Hexane Solutions under γ-Radiolysis

The influence of structurally different dihydric phenols on the radical reactions of hexane in deaerated solutions under -irradiation was studied. It was found that 4-tert-butylpyrocatechol (I), 3,5-diisopropylpyrocatechol (II), 2,5-di-tert-butylhydroquinone (III), and 4,6-di-tert-butylresorcinol (IV) effectively inhibited the formation of hexyl radical combination products. Using the chromatography–mass spectrometry technique, it was shown that the adducts of alkyl radicals with I–III have the structure of a monoalkyl ether. Phenol IV gave a mixture of dimers with O- and C-alkylation products.     

The structure of tetraarylantimony halides and tetraphenylantimony isothiocyanate

X-ray diffraction analysis is used to study tetraphenylantimony fluoride (I), tetra-p-tolylantimony (II), and tetraphenylantimony isothiocyanate (III), where Sb atom has a distorted trigonal-bipyramidal coordination. The Sb-C bond lengths in I–III lie a range of 2.102(1)–2.183(1) Å; the Sb-F, Sb-Cl, and Sb-N distances are equal to 2.0530(8) Å, 2.7319(7) Å, and 2.507(2)Å, respectively, in I, II, and III.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 117–124.Original Russian Text Copyright © 2005 by Sharutin, Sharutina, Pakusina, Smirnova, Pushilin.     

Synthesis,characterization, and catalytic oxidation of styrene,cyclohexene, allylbenzene,and cis-cyclooctene by recyclable polymer-grafted Schiff base complexes of vanadium(IV)

Schiff base-functionalized chloromethylated polystyrenes, PS-[Ae-Eol] (I), PS-[Hy-Eda] (II) and PS-[HyP-Eda] (III), were synthesized by reacting 2-(2-aminoethoxy)ethanol (Ae-Eol), N-(2-hydroxyethyl)ethylenediamine (Hy-Eda), and N-(2-hydroxpropyl)ethylenediamine (HyP-Eda) with oxidized chloromethylated polystyrene. Oxidized chloromethylated polystyrene (PS-CHO) was prepared by oxidation of chloromethylated polystyrene (PS) with sodium bicarbonate in DMSO. By reacting DMSO solution of [VO(acac)₂] with polymer-anchored Schiff base ligands I, II, and III, vanadium(IV) complexes PS-[V^IVO(Ae-Eol)] (1), PS-[V^IVO(Hy-Eda)] (2), and PS-[V^IVO(HyP-Eda)] (3) were prepared. Structure and bonding of I, II, and III as well as corresponding vanadium complexes 1, 2, and 3 were confirmed by FT-IR, UV–vis spectroscopy, SEM, EDX, AAS, TGA, EPR, etc. Polymer-anchored vanadium(IV) complexes 1, 2, and 3 show, efficient catalysis toward oxidation of styrene, cyclohexene, allylbenzene, and cis-cyclooctene in the presence of hydrogen peroxide. Optimized reaction conditions for the oxidation of these alkenes was achieved by changing various reaction parameters (like amount of catalyst, amount of oxidizing agent, volume of solvent, etc.). Polymer-grafted 1, 2, and 3 can be reused multiple times without depletion of their activity.     

Study of substituent effects on rotational isomers and monomer–dimer equilibria of the 3-carboxy group in 4-substituted (R)-2-(3,4-methylenedioxyphenyl)-6-isopropyloxy-2H-chromen-3-carboxylic acids in dilute CCl4 and CHCl3 solutions by FTIR spectroscopy

FTIR spectra of the title carboxylic acids (I–III) with 4-substituents (H, CH₃ or C₆H₅) and their related compounds IV–VI with 4-(substituted phenyl) groups were measured in dilute CCl₄ and CHCl₃ solutions. The concentration dependence of FTIR spectra of I–IV was also measured in these solutions. These spectra were subjected to curve analysis in order to quantitatively identify the rotational isomers of 3-carboxy group attributable to steric hindrance of the 4-substituents. For I, II and III–VI, two, four and five ν(CO) bands were observed for their carboxy groups, respectively, indicative of monomer–dimer equilibrium and two and three kinds of rotational isomers for II and III–VI, respectively. Compounds III–VI were found to form intra-molecular hydrogen bonds between the trans-type of the 3-carboxy group and the π-electrons in the 4-benzene ring. We have worked out a method to estimate the association constant (K) of complicated monomer–dimer equilibria such as II–VI. The K values of I–IV decrease remarkably in the order of H (I), C₆H₅ (III), CH₃ (II) and C₆H₄-p-OCH₃ (IV) in CCl₄ and I, II, III and IV in CHCl₃; these orders are discussed.     

Synthesis and Structure of Tetra- and Triphenylantimony Organosulfonates

Tetraphenylantimony 2-naphthalenesulfonate (I), tetraphenylantimony phenylmethanesulfonate (II), and bis(tetraphenylantimony) sulfate (III) were synthesized via reaction of pentaphenylantimony with 2-naphthalenesulfonic acid, triphenylantimony bis(phenylmethanesulfonate), and triphenylantimony sulfate, respectively, in toluene. Triphenylantimony bis(phenylmethanesulfonate) (IV) was synthesized from triphenylstibine, phenylmethanesulfonic acid, and hydrogen peroxide (taken in the molar ratio of 1 : 2 : 1). Organoantimony betaine (V) was obtained by reacting triphenylstibine with phenylmethanesulfonyl chloride in the presence of hydrogen peroxide. The structures of the compounds synthesized were determined using X-ray diffraction analysis. The Sb atoms in I–IV have distorted trigonal bipyramidal coordination. The Sb–C and Sb–O distances are equal to 2.100(4)–2.140(3) and 2.644(2) Å in molecule I, 2.105(2)–2.131(2) and 2.699(1) Å in II, 2.096(6)–2.169(6) and 2.101(6), 2.271(3) Å in III, and 2.101(3)–2.102(5) and 2.111(2) Å in IV. In V, the Sb atoms have close tetrahedral (2.105–2.115 Å) and remote (2.65, 3.019 Å) octahedral environment (the oxygen atoms of sulfo group of their own and neighboring molecules). Two betaine molecules are joined through the O atoms of the sulfo groups of bidentate phenylmethanesulfonate ligands to form a centrosymmetrical dimer. The intermolecular C(1)–H(1)···O(1) hydrogen bonds (3.10 Å) are formed that strengthen the dimer.     

Binuclear Copper(II) Complexes with Terpene Bicyclic Optically Active Iminoalcohol: Synthesis,Structure, and Magnetic Properties

Methods were developed for synthesizing the 3-Carene derivative (1R)-1-|(1R,2R,5R)-2-benzyl-3-imino-6,6-dimethylbicyclo[3.1.0]hex-2-yl}-ethanol (HL) and stable copper(II) complexes [Cu₂(H₂O)L₂(CH₃COO)₂] · H₂O (IV), [Cu₂L₂Cl₂] (V), and [Cu₂L₂Br₂] (VI). According to X-ray diffraction data, IVand Vhave molecular binuclear structures with a planar Cu₂O₂cycle. The CuOCu angles are equal to 102.2°, 102.8° (IV) and 103.2°, 103.8° (V). The L^–terpene ligand acts as a tridentate cyclic bridge. A strong antiferromagnetic exchange interaction between the unpaired electrons of the copper(II) ions was detected in compounds IV–VIusing the static magnetic susceptibility method. The –2Jparameter for IV, V, and VIis equal to 660, 1000, and 1060 cm^–1, respectively.     

Rh(I) carbonyl carboxylato complexes: Spectral and structural characteristics. Some reactions of coordinated formate group

Complexes [Rh(µ-RCOO)(CO₂)]₂ , where R = H, CH₃,CF₃ (I, II, III, respectively) are synthesized by reacting anhydrous carboxylic acids with Rh(Acac)(CO₂) crystals. In compounds I, II, III, and trans-Rh(RCOO)(PPh₃)₂(CO), where R = H, CH₃, CF₃ (IV, V, VI, respectively), (CO) and ¹J(CRh) increase and ¹³C decreases with the increasing electronegativity of R (CH₃ < H < CF₃). In the case complexes IV, V, and VI, the values of ³¹P and ¹ J(PRh) decrease in the same order. Complexes I and V are studied by X-ray diffraction analysis. Intramolecular (2.946 Å) and intermolecular (3.127 Å) Rh-Rh distances in a columnar structure I are close, i.e., the structure contains infinite chains of metal atoms. Interaction of IV with chlorinated solvents results in trans-RhCl(PPh₃)₂(CO). When heated with an excess of PPh₃ in propanol-2, compound IV transforms to HRh(PPh₃)₃(CO). The latter reaction was suggested as a basis of a new method that can be used to obtain HRh(PPh₃)₃(CO).Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 132–142.Original Russian Text Copyright © 2005 by Varshavskii, Cherkasova, Podkorytov, Korlyukov, Khrustalev, Nikolskii.     

Preparation and reactivity of polyfunctional six- and eight-membered cyclic silicates

Six- and eight-membered cyclic silicates with reactive SiH or Si-vinyl functional groups have been prepared: hexakis(dimethylsiloxy)cyclotrisiloxane (I), hexakis(vinyldimethylsiloxy)cyclotrisiloxane (II), octakis(dimethylsiloxy)cyclotetrasiloxane (III) and octakis(vinyldimethylsiloxy)cyclotetrasiloxane (IV). Reaction of pseudo wollastonite (Ca₃Si₃O₉) with dimethylchlorosilane or vinyldimethylchlorosilane gives I and II, respectively. IV has been prepared similarly by reaction of octakis[chloro calcium oxy]cyclotetrasilicate [Ca₈Si₄O₁₂Cl₈] with vinyldimethylchlorosilane. On the other hand, acid catalyzed siloxane exchange between tetramethyldisiloxane and octakis(trimethylsiloxy)cyclotetrasiloxane (V) gave III. Cyclic silicates (I-VI) are surprisingly resistant to acid catalyzed ring opening polymerization. In addition, II, IV, V and hexakis(trimethylsiloxy)cyclotrisiloxanes (VI) are resistant to phosphazene P₄-t-Bu superbase catalyzed ring opening polymerization.     

Synthesis and crystal structure of cobalt(III) α-dioximates with pyrazine

A series of new coordination compounds of cobalt(III) trans-dioximates with pyrazine [CoCl(DH)₂Pz] · H₂O (I), [CoBr(DH)₂Pz] · H₂O (II), [Co(DH)₂Pz₂]NO₃ · H₂O (III), [Co(DH)₂Pz₂][BF₄] (IV), [Co(MgH)₂Pz₂][BF₄] (V), and [Co(NioxH)₂Pz₂][BF₄] (VI), where DH, MgH, and NioxH are dimethylglyoxime, methylglyoxime, and 1,2-cyclohexanedionedioxime monoanions, respectively, Pz is a pyrazine molecule were synthesized. The structures of compounds I, II, and VI were determined by X-ray diffraction. The Co(III) environment in these compounds is octahedral and the pseudomacrocyclic (DioxH⁻)₂ fragment occurs in the equatorial plane. This fragment is stabilized by O-H…O hydrogen bonds. The neutral Pz ligand is monodentate in all three compounds.     

N-Aryl-3-Aminopropionic acids as selective reagents for the determination of copper in metallurgical products

Analytical characteristics of N,N-di(2-carboxyethyl)aniline (I), N,N-di(2-carboxyethyl)-3,4-xylidine (II), N-(2-carboxyethyl)anthranilic acid (III), N,N-di(2-carboxyethyl)-4,5-dimethylaminoazobenzene-4-sulfonic acid (IV), and N-(2-carbamoylethyl)anthranilic acid (V) were studied. The factors affecting the selectivity of I–V for Cu(II) ions (basicity of the amino group, nature and positions of substituents in the benzene ring, and geometry of chelate cycles) were analyzed. The optimum conditions were found and procedures were developed for the spectro-photometric determination of copper in metallurgical products. The high selectivity of I–V for Cu(II) ions allows the determination without preliminary separation of concomitant components in aqueous solutions without organic solvents. Compound II exhibits the best analytical characteristics: the analytical range of copper 3–20 mg/L, detection limit 0.7 mg/L, ( = 252 nm) = 3290 L mol^–1 cm^–1, and pH 6.0 (ammonia-acetate buffer solution).Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 271–277.Original Russian Text Copyright © 2005 by Neudachina, Osintseva, Skorik, Vshivkov.     

Phytochemical investigation of Gynura bicolor leaves and cytotoxicity evaluation of the chemical constituents against HCT 116 cells

Gynura bicolor (Compositae) is a popular vegetable in Asia and believed to confer a wide range of benefits including anti-cancer. Our previous findings showed that the ethyl acetate extract of G. bicolor possessed cytotoxicity and induced apoptotic and necrotic cell death in human colon carcinoma cells (HCT 116). A combination of column chromatography had been used to purify chemical constituents from the ethyl acetate and water extract of G. bicolor leaves. Eight chemical constituents 5-p-trans-coumaroylquinic acid (I), 4-hydroxybenzoic acid (II), rutin (III), kampferol-3-O-rutinoside (IV), 3,5-dicaffeoylquinic acid (V), kampferol-3-O-glucoside (VI), guanosine (VII) and chlorogenic acid (VIII) were isolated from G. bicolor grown in Malaysia. To our best knowledge, all chemical constituents were isolated for the first time from G. bicolor leaves except rutin (III). 3,5-dicaffeoylquinic acid (V), guanosine (VII) and chlorogenic acid (VIII) demonstrated selective cytotoxicity (selective index>3) against HCT 116 cancer cells compared to CCD-18Co human normal colon cells.     

Effect of Poly(methacrylic acid) on Photoinduced Processes with Cyanine Dyes in Aqueous Solutions

The cyanine dyes thiamonomethinecyanine (I), thiacarbocyanine (II), and thiadicarbocyanine (III) in an aqueous poly(methacrylic acid) (PMA) solution form different molecular species: monomers anchored to PMA, dimers, and H aggregates, in proportions determined by the [dye]/[PMA] concentration ratio. Each molecular species is characterized by its own probabilities of radiative and nonradiative transitions: the absence of photoisomerization for I–IIIdimers and H aggregates, the absence of fluorescence for H aggregates of IIand III, the capability of transition to a triplet state for PMA-anchored monomers I–III, and considerable enhancement of intersystem crossing to the triplet state for the dimers of II.     

Reactions of Chelate Complexes with Macrocyclic Ligands. Octaphenyltetraazaporphine and Its Derivatives

Coordination of three azaporphines, namely, octaphenyltetraazaporphine (I), octa(4-nitrophenyl)-tetraazaporphine (II), and octa(4-bromophenyl)-tetraazaporphine (III) with some chelate salts of copper and zinc (hydroxyquinolate (IV), -nitroso--naphtholate (V), glycinate (VI), alaninate (VII), valinate (VIII), leucinate (IX), and glutaminate (X)) in DMSO were studied. As in the case with acetates, compound I was found to coordinate chelate salts according to the monomolecular mechanism and to give amino complex with the bridging nitrogen atom. Compound II reacts with all indicated salts according to the bimolecular mechanism almost instantaneously, except for VII. In the same way, reactions of III are also instantaneous, even with VII. Coordination of I with Zn(II) chelate salts proceeds at the rates higher than with acetate.     

Ionization potentials, singlet and triplet excited states and frontier MOs study of 9-ethylidenefluorene, 9-iminofluorene, fluoren-9-one and some of its diazaderivatives

9-Ethylidenefluorene (I), 9-iminofluorene (II), fluoren-9-one (III), 1,4-diazafluoren-9-one (IV), 1,8-diazafluoren-9-one (V) and 4,5-diazafluoren-9-one (VI) have been investigated by means of the all-valence-electrons INDO/S-CI approximation. The electronic structure (including the lowest energy triplet states) is discussed on the basis of the frontier molecular orbitals and a good agreement with experiment is found. The lowest energy n orbital appears slightly overestimated but on the whole the calculated MO's energies agree fairly well with the available experimental ionization potentials. The PES spectrum of VI is also reported.     

Syntheses and structures of tris(<Emphasis Type="Italic">para</Emphasis>-tolyl)-, tris(3-fluorophenyl)-, and tris(4-fluorophenyl)antimony dioximates

Tris(para-tolyl)antimony bis(2-oxybenzaldoximate) (I), tris(para-tolyl)antimony bis(2-nitrobenzaldoximate) (II), tris(para-tolyl)antimony bis(2-bromobenzaldoximate) (III), tris(3-fluorophenyl)antimony bis(2-oxybenzaldoximate) (IV), tris(4-fluorophenyl)antimony bis(2-bromobenzaldoximate) (V), and tris(4-fluorophenyl)antimony bis(2-nitrobenzaldoximate) (VI) are synthesized by the reactions of tris(paratolyl)-, tris(3-fluorophenyl)-, and tris(4-fluorophenyl)antimony with 2-oxy-, 2-nitro-, and 2-bromobenzaldoxime in diethyl ether in the presence of tert-butyl hydroperoxide. The Sb atoms in complexes I–VI have a distorted trigonal bipyramidal coordination mode with the oximate ligands in the axial positions. CIF files CCDC nos. 1062231 (I), 1059962 (II), 1465384 (III), 1465109 (IV), 1471948 (V), and 1060387 (VI).     

Selective determination of 4-aminobenzoic and 4-aminosalicylic acid derivatives in mixtures by flow-injection analysis

The working conditions were found for the determination of medicinal substances anesthesin (benzocaine,I), novocaine (II), novocainamide (procainamide,III), and sodium 4-aminosalicylate (IV) as their 4,6-dinitrobenzofuroxan derivatives by flow-injection analysis with spectrophotometric detection (λ 510 nm). The best conditions were attained using a mixture of ethanol (methanol) and a buffer solution of pH 6.68 (30: 70 vol %). The analytical range for the analytes was 0.08-5.0 μg/mL. The detection limits (3σ,n = 4) were 0.04 (I), 0.05 (II), 0.07 (III), and 0.03 (IV) μg/mL. Procedures for determining 4-aminobenzoic and 4-aminosalicylic acid derivatives in pharmaceuticals containing ephedrine, atropine, dimedrol, and inorganic salts and in biological fluids (protein hydrolyzate, blood plasma, and whole blood) were developed.