Complexation of uranium by 2-(2-thiazolylazo)-4-methoxyphenol and 2-(2-thiazolylazo)-5-methoxyphenol

A comparative study has been made of the complexation of uranium(VI) by 2-(2-thiazolyl)-4-methoxyphenol (TAMH) and 2-(2-thiazolylazo)-5-methoxyphenol(TAMR). The complexes are less stable and have lower molar absorptivities than the PAR and TAR complexes but are still useful for determination of uranium. The TAMH chelate can be extracted into isobutyl methyl ketone. Both complexes are 1:1 metal :ligand. For the TAMH complex log beta(1) = 8.8, = 1.4 x 10(4) at 610 mmu; for the TAMR complex log beta(1) = 8.1, = 2.0 x 10(4) at 530 mmu.     

Spectrophotometric determination of thallium with 4-(2-pyridylazo)resorcinol and 4-(2-thiazolylazo)resorcinol

Thallium(III) gives sensitive reactions with PAR and TAR (epsilon = 2 x 10(4) at 520 nm), forming 1:1 complexes at pH approximately 1-2, and a mixture of 1:1 and 1:2 complexes at higher pH values; hydrolysis sets in above pH approximately 3. The stability constants are evaluated.     

Spectrophotometric determination of cobalt in steel with 2-(2-thiazolylazo)-4-methyl-5-(sulfomethylamino) benzoic acid (TAMSMB)

Microchimica Acta - A method for the determination of cobalt in steel with 2-(2-thi-azolylazo)-4-methyl-5-(sulfomethylamino) benzoic acid (TAMSMB) is proposed. Iron and manganese were previously...     

Relative stabilities of metal complexes of 4-(2-pyridylazo)resorcinol and 4-(2-thiazolylazo)resorcinol

The stability constants of 1:1 complexes of 4-(2-pyridylazo)resorcinol (PAR) and 4-(2-thiazolylazo)resorcinol (TAR) with Mn(II), Ni(II), Cu(II) and Zn(II) have been determined spectrophotometrically at μ = 0.1 and 25°C. The method is based on indirect estimation of the protonated and normal complexes by measuring the ligand absorption peak. Both protonated and normal complexes of these metals with PAR are more stable than those with TAR. The reverse order was previously observed for the pronated complexes of the lanthanides(III). The different behaviour of the 3d transition metals(II) compared to the lanthanides(III) is discussed. The proton dissociation constants of the protonated complexes of PAR or TAR with various metals are also discussed.     

Syntheses and spectrophotometric studies of 2-(2-thiazolylazo)- and 2-(2-benzothiazolylazo)-5-dimethylaminobenzoic acids as analytical reagents: Determination of nickel

2-(2-ThiazolyIazo)-5-dimethylaminobenzoic acid (TAMB) and 2-(2-benzothiazolylazo)-5-dimethylaminobenzoic acid (BTAMB) have been synthesized, and their potential for determinations of metals has been studied spectrophotometrically. Both are extremely sensitive chromogenic reagents for the determination of nickel. Molar absorptivities in aqueous methanol are 0.95 × 10⁵ (TAMB) and 1.2 × 10⁵ (BTAMB). In aqueous methanol, at apparent pH 5–9.5, the system conforms to Beer's law for 0.05–0.5 ppm nickel; Cu, Cr, Co, Pd and Fe interfere, but they can easily be masked.     

Crystal structure of bis(2-(2-thiazolylazo)-4-methylphenol)cobalt(III)chloride.

The reaction between CoCl2 x 6H2O and 2-1-(2-thiazolylazo)-p-cresol (TAC) in acetone resulted in six coordinated cobalt(III) complex, [Co(TAC)2]Cl3. Two TAC ligands coordinate with cobalt ion forming four five membered chelate rings. The cobalt ion is octahedrally coordinated by a phenolic oxygen, azo nitrogen and nitrogen in thiazole rings. Three chloride ions are disordered.     

Micellar chromatographic separation of vanadium(V) chelate with 2-(2-thiazolylazo)-5-dimethylaminophenol

Summary In reversed phase—high performance liquid chromatography for metal chelates with 2-(2-thiazolylazo)-5-dimethylaminophenol, an aqueous non-ionic surfactant solution is used as a mobile phase. Among V(V), Fe(III), Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Mn(II), and Al(III), only the V(V) chelate gave a resolved peak by using 0.8% w/w poly(oxyethylene)_n-4-nonylphenyl ether (n=20) solution buffered at pH 3.8. V(V) can be selectively separated and sensitively determined.     

Spectrophotometric determination of chromium(III) with 4-(2-thiazolylazo)-resorcinol

Summary The red complex formed between chromium(III) and 4-(2-thiazolylazo)-resorcinol (1 2) at pH 5.0, on heating the reactants to 90° for 45 minutes, is used for Spectrophotometric determination of chromium, the absorbance being measured at 525 nm. Beer's law is obeyed for chromium concentration of 0.06 to 1.1g per ml. Molar absorptivity is 4.98×10⁴ and Sandell sensitivity 0.001g cm^–2. This method has been applied to the determination of chromium content in steel samples.

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Zusammenfassung Der 1 2-Komplex von Chrom(III) mit 4-(2-Thiazolylazo)resorcin bildet sich bei pH 5,0 und 90° C in 45 min. Er eignet sich zur spektrophotometrischen Chrombestimmung. Die Extinktion wird bei 525 nm gemessen. Das Beersche Gesetz ist zwischen 0,06 und 1,1g Cr/ml erfüllt. Die molare Extinktion beträgt 4,98 · 10⁴, die Empfindlichkeit nach Sandell 0,0001g · cm^–2. Die Methode wurde zur Chrombestimmung in Stahlproben angewandt.

     

Dioxo-[4-(2-thiazolylazo)resorcinolo]vanadate(V) complexes

The preparation and characterization of dioxo-[4-(2-thiazolylazo)resorcinolo] vanadate(V) complexes are reported. According to chemical and spectral evidence and comparison with vanadium-[4-(2-pyridylazo)resorcinolo] complexes obtained analogously, the stable crystalline complex compounds correspond to the formula [(C₆H₅)₄X][V^VO₂TAR]·nH₂O, X = As, P; n = 0, 1.     

Reversed-phase HPLC determination of Co(II), Ni(II) and Fe(III) as their 2-(2-thiazolylazo)-5-dimethylaminophenol chelates

The optimum chromatographic separation conditions for Co(II), Ni(II), and Fe(III) chelates with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM) were investigated. The compositions of chelates were also determined by the HPLC method and thus the possible structure of chelates was given. A precolumn derivatization method was used, followed by separation on an octyl-bonded silica stationary phase with a methanol-tetrahydrofuran-water (40:9:51, v/v/v) mobile phase containing pH 5.8 acetate buffer and 1 x 10(-4)M TAM. The detection limits of Co(II), Ni(II), and Fe(III) at 560 nm are 0.03, 0.02 and 0.1 ng (S N = 2 ), respectively. They can be determined by means of the proposed method without interference from other common metal ions and have been determined in five standard alloys with satisfactory results.     

Poly (4-methoxyphenol) film as a galactose-sensing material

Poly (4-methoxyphenol)-galactose oxidase biosensor for galactose is reported. This amperometric biosensor was prepared in a one-step procedure by electrochemical polymerization of the relevant monomer in the presence of galactose oxidase on Pt electrode surface in a KCl solution at potential of 0.6 V vs. Ag/AgCl. From the steady-state amperometric responses to galactose of the resulting polymeric biosensor, its sensor characteristics such as feasibility of preparation, linear range, response time, selectivity and stability were evaluated.     

Complexing properties of thiazolylazophenols and spectrophotometric determination of iron(II) with 2-(2-benzothiazolylazo)-4-methoxyphenol

Summary Thiazolylazophenols containing a methyl or a phenyl group in the thiazole ring were synthesized and their potential for the spectrophotometric determination of iron were studied. These dyes react with iron(II) to form brownish complexes, which show a characteristic absorption in near-infrared region. Among them, 2-(2-benzothiazolylazo)-4-methoxyphenol is most suitable and the iron(II) complex has the absorption maximum at 815 nm in chloroform. The optimum pH for iron extraction lies between 5.5–9.5 and Beer's law holds up to 6 ppm of iron, with a molar absorptivity of 1.47×10⁴ 1 mol^–1 cm^–1. The composition and the extraction constant of the complex was found to be FeBTAMP=12 and log K_ex=–0.76±0.12, respectively. Many kinds of ions can be tolerated even in the presence of large amounts. The method has been applied to the determination of iron in mixtures containing 3d type metal ions, natural waters and native sulfurs with satisfactory results.

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Komplexbildende Eigenschaften von Thiazolylazophenol und spektro-photometrische Bestimmung von Eisen(II) mit 2-(2-Benzothiazolylazo)-4-methoxyphenol

Zusammenfassung Thiazolylazophenol mit einer Methyl- bzw. Phenylgruppe am Thiazolring wurde synthetisiert und seine Eignung für die spektrophotometrische Bestimmung von Eisen(II) studiert. Diese Farbstoffe bilden mit Fe(II) bräunliche Komplexe, die charakteristische Absorption im nahen IR zeigen. Unter ihnen ist 2-(2-Benzothiazolylazo)-4-methoxyphenol am besten geeignet. Der Fe(II)-Komplex hat ein Absorptionsmaximum bei 815 nm in Chloroform. Das optimale pH für die Eisenextraktion liegt zwischen 5,5 und 9,5; das Beersche Gesetz ist bis zu 6 ppm Fe erfüllt, der molare Extinktionskoeffizient beträgt 1,47×10⁴ l·mol^–1·cm^–1. Fe(II)BTMP=12. Die Extraktionskonstante ist log K_ex=–0,76±0,12. Zahlreiche Ionen stören auch in größerer Menge nicht. Die Methode wurde zur Eisenbestimmung in Gemischen mit 3d-Typ-Metallen, in natürlichen Wässern und in inländischem Schwefel angewandt.

     

Rapid spectrophotometric determination of manganese(II) with 4-(2-thiazolylazo)-resorcinol

Summary Manganese forms a red chelate with 4-(2-thiazolylazo)-resorcinol at pH 8.8 (borate buffer), and absorbance is measured after 30 s, at 540 nm in the presence of 20%tert-butyl alcohol (by volume). The 12 complex obeys Beer's law for manganese concentration of 0.04–1.4g per ml, has molar absorptivity 4.176 x 10⁴ and Sandell sensitivity 0.0013g cm^–2. The formation constant (logK) is found to be 9.32, and relative standard deviation ±0.22%. Of the 48 ions studied for interference, only Co(II), Zn(II), Cd(II), Pb(II) and EDTA^2– are found to interfere. This method has been applied for the determination of manganese content in alloy steels.

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Spektrophotometrische Bestimmung von Mangan(II) mit 4-(2-Thiazolylazo)-resorcin

Zusammenfassung Mangan bildet bei pH 8,8 (Boratpuffer) mit 4-(2-Thiazolylazo)-resorcin ein rotes Chelat, dessen Absorbanz nach 30 sec bei 540 nm in Gegenwart von 20% tert. Butylalkohol gemessen wird. Dieser 12-Komplex entspricht bei einer Mangan-Konzentration von 0,04–1,4g/ml dem Beerschen Gesetz; seine molare Absorption beträgt 4,176 x 10⁴, die Empfindlichkeit nach Sandell 0,0013g·cm^–2. Die Bildungskonstante (log K) beträgt 9,32, die rel. Standardabweichung ±0,22%. Unter 48 untersuchten Ionen erwiesen sich nur Co(II), Zn(II), Cd(II), Pb(II) und EDTA als störend.-Das Verfahren wurde zur Bestimmung des Mangangehaltes in Stahl verwendet.