Nachweis und gravimetrische bestimmung von thallium mit 8-Hydroxychinolin und 2.5-Dibrom-8-Hydroxychinolin

The ready formation of innercomplex, water-insoluble Thallium(III)-oxinate and Dibromoxinate from masked Thallium(III) Salt-Solutions permits the detection and gravimetric determination of Thallium. Procedures are described.     

Indirekte komplexometrische Bestimmung einiger Hydrazinderivate

Zusammenfassung Es wurde die Oxydation einiger organischer Stoffe mit Thallium(III)- salz untersucht. Zur Bestimmung von Isonicotinsäurehydrazid, Semicarbazid-chlorid und Benzoylhydrazin ist ein Arbeitsgang vorgeschlagen worden, bei dem der zu bestimmende Stoff mit überschüssigem Thallium(III)-sulfat oxydiert wird, dessen unverbrauchte Menge durch komplexometrische Titration unter Verwendung von 1-(2-Pyridylazo)-2-resorcin als Indicator bestimmt wird.     

Determination of traces of thallium by fluorimetric titration

Summary Thallium(I) shows strong fluorescence in a solution which is 3.3 M in HCl and 0.8 M in KCl. The excitation wavelength is 253 nm and the wavelength selected for the fluorescence 438 nm. Due to the strong absorption at 253 nm by thallium(III) a reductometric rather than an oxidimetric titration will lead to a correct fluorimetric end-point indication. The precision and the selectivity of the titrimetric method are better than those of the corresponding methods based on the use of calibration curves. Traces of thallium down to 1 g can be determined with good precision. The method can be used for the determination of thallium in urine at the ppm level.

---

Bestimmung von Spuren Thallium durch fluorimetrische Titration

Zusammenfassung Thallium(I) zeigt starke Fluorescenz in einer Lösung, die 3,3 M an HCl und 0,8 M an KCl ist. Diese Erscheinung wurde zur Endpunktsanzeige der Redoxtitration Tl(III)-Tl(I) verwendet (Excitationswellenlänge 253 nm, Fluorescenzwellenlänge 438 nm). Wegen der starken Lichtabsorption von Thallium(III) bei 253 nm kann nur ein reduktometrisch durchgeführtes Titrationsverfahren benutzt werden. Genauigkeit und Selektivität sind beim titrimetrischen Verfahren besser als beim Eichlinienverfahren. Spuren Thallium (bis einige Mikrogramm) können mit guter Genauigkeit bestimmt werden. Die Anwendung der Methode für die Bestimmung von Thallium in Urin im ppm-Bereich wird beschrieben.

     

A simple and rapid spectrophotometric method for determination of ultra trace amounts of thallium(III) with 4-(4'-N,N-dimethylaminophenyl) urazole as a new reagent

A simple and selective spectrophotometric method is proposed for the determination of ultra trace amounts of Tl(III). The reported method is based on the oxidation of 4-(4'-N,N-dimethylaminophenyl)urazole (DAPU) to the corresponding triazolinedione (TAD) by Tl(III) at pH 4.0. The reaction was monitored spectrophotometrically by measuring the increasing color of TAD compound at 514 nm by the fixed-time method. At a given time of 2.0 min at 30 degrees C, the working range of calibration was 5.0 x 10(-8) - 2.0 x 10(-5) M Tl(III) and detection limit of 5.0 x 10(-8) M was obtained. The influences of pH, reagent concentration, ionic strength and temperature were studied. The effect of diverse ions on the determination of Tl(III) by the proposed method was also investigated. Thallium in real samples was determined by this method, with satisfactory results.     

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.     

Biamperometrische Indikation in der Chelatometrie

Zusammenfassung Der Endpunkt von komplexometrischen Titrationen (mit ÄDTE) kann biamperometrisch besonders gut indiziert werden, wenn man zur Titrationslösung eine geringe Menge Thallium(III)-ÄDTA zusetzt. Auf diese Weise erhält man nach dem Äquivalenzpunkt einen starken Anstieg des Diffusionsstromes. An die Elektroden wird eine Spannung von 1,0 V angelegt. Thallium(III)-ÄDTA ist am wirksamsten im pH-Bereich zwischen 6 und 10.

---

Biamperometric indication in chelatometryImprovement of the end-point indication by means of thallium(III)-EDTA

The biamperometric indication of chelatometric titrations with EDTA is greatly improved, if a small amount of thallium(III)-EDTA is added to the solution to be titrated. Thus, an appreciable increase of the diffusion current is obtained after the equivalence point. A voltage of 1,0 V is applied to the platinum electrodes. Thallium(III)-EDTA is most effective in the pH-range between 6 and 10.

     

Die Bestimmung kleiner Mengen Thallium in Blei. Extraktion des Thallium(III)-chlorids mit Isopropyl?ther

Zusammenfassung Zwecks Bestimmung kleiner Gehalte von Thallium in Blei wird das Thallium als Thallium(III)-chlorid aus der mit Brom oxydierten Lösung mittels Isopropyläther extrahiert und jodometrisch titriert. Gehalte von 0,05–1% in Blei lassen sich mit einer Genauigkeit von –0,5% bestimmen.     

The spectrophotometric determination of thallium(iii)by ternary complex formation

If thallium(III) is added to an aqueous solution of potassium thiocyanate containing a large amount of pyridine in the pH range 5.2–5.5, a yellow solution which is stable in diffuse light is obtained. The yellow colour can be measured at 405 nm for the colorimetric determination of thallium(III) in the range 20–300 μg Tl ml^-1. The complex is a mixed ligand complex with a metal-ligand ratio of 1:2:2. Thallium(I) does not interfere. The interference of various other metal ions and anions is discussed.     

Direct potentiometric determination of tin(II) and (IV), antimony(III), thallium(III), rhenium(VII), and bismuth(III) with cetylpyridinium chloride

Summary The precipitation titrations of the following elements vs. cetylpyridinium chloride were investigated: Rhenium as perrhenate, tin as the (II) and (IV) species, antimony(III), thallium(III), and bismuth(III) as their halogen complexes. Optimum conditions for the determinations are described. Of the elements examined only thallium(III) also could be titrated potentiometrically vs. tetraphenylarsonium chloride. Titrations were monitored with a simple sensor consisting of a graphite rod coated with poly(vinyl chloride) and dioctylphthalate, and a double-junction reference electrode.

---

Direkte potentiometrische Bestimmung von Zinn(II) und (IV), Antimon(III), Thallium(III), Rhenium(VII) und Bismut(III) mit Hilfe von Cetylpyridiniumchlorid

Zusammenfassung Die Fällungstitration der genannten Elemente mit Cetylpyridiniumchlorid wurde untersucht: Re als Perrhenat; Zinn in 3- und 4wertiger Form; Sb(III), Tl(III) und Bi(III) in Form ihrer Halogenkomplexe. Die optimalen Bedingungen werden mitgeteilt. Nur Thallium(III) kann auch potentiometrisch gegen Tetraphenylarsoniumchlorid titriert werden. Die Titrationen werden mit Hilfe eines einfachen Sensors kontrolliert, der aus einem mit Polyvinylchlorid und Dioctylphthalat überzogenen Graphitstab besteht sowie einer double-junction Bezugselektrode.

     

Determination of thallium in natural waters by electrothermal atomic absorption spectrometry

Thallium is determined in natural waters by electrothermal atomic absorption Spectrometry after preconcentration. Thallium is oxidized and retained as the tetrachlorothallate (III) ion on an anion exchange column, followed by elution with ammonium sulfite solution. A concentration factor of 400 is achieved. The detection limit of the method is 3.3 ng/1.     

A diastereoselective total synthesis of trans-trikentrin A: a ring contraction approach

A new route to obtain the polyalkylated indole (+/-)-trans-trikentrin A was developed. The synthesis of this natural alkaloid features a thallium(III)-mediated ring contraction reaction to obtain the trans-1,3-disubstituted five-membered ring in a diastereoselective manner. Thallium(III) is chemoselective in this rearrangement, reacting with the olefin without oxidation of the indole moiety. Other key transformations are the Bartoli's reaction to construct the heterocyclic ring and a Heck coupling to add the carbons atom that will originate the nonaromatic cycle.     

An Unusual Reaction of Methyl 3,5-Dimethoxybenzoate with Thallium(III)Trinitrate - Trifluoro Acetic Acid

Thallium(III)trinitrate trihydrate (TTN) is known to be a useful and extremely versatile reagent in organic synthesis.^1-5 Its use has been exploited mainly in oxidation and oxidative rearrangements of chalcones, aromatic ketones and phenols. In this communication, we report an unusual reaction of polyoxygenated methylbenzoates with TTN.     

Determination of thallium(III) by use of a mercury reductor

A convenient method has been developed for the determination of thallium(III) by using a mercury reductor. Thallium(III) is reduced to thallium(I) in 0.5–4N hydrochloric or sulphuric acid medium and the determination is completed by oxidative titration with potassium bromate. The method is extended to analysis of thallium(III)-thallium(I) and thallium(III)-iron(III) mixtures.     

Complexometric titration of gallium, indium and thallium(III) using sodium azide as a metal indicator

Summary Thallium(III) has been determined between pH 4.0 and 6.0 by titration against EDTA using sodium azide as indicator. The metal ion gives a bright yellow colour which is discharged at the equivalence point. Micro-quantities upto about 1 mg of the metal have been determined with accuracy. The end-point has also been determined photometrically. Gallium(III) and indium(III) can also be determined by back-titration of the excess of EDTA added to each of these ions against a standard ferric chloride solution using sodium azide as indicator.

---

Zusammenfassung Thallium(III) wird durch Titration mit ÄDTA-Lösung bei pH 4,0–6,0 gegen Natriumazid als Indicator bestimmt. Der Umschlag am Endpunkt erfolgt von Gelb nach Farblos. Mikromengen bis zu 1 mg können mit guter Genauigkeit erfa\t werden. Die Bestimmung kann auch photometrisch durchgeführt werden. Gallium(III) und Indium(III) können durch Rücktitration von überschüssigem ÄDTA mit Eisen(III)-chloridlösung bestimmt werden, wobei ebenfalls Natriumazid als Indicator dient.

     

Thallimetric oxidations-VI Titrimetric and spectrophotometric methods for the determination of phosphite and analysis of binary mixtures of phosphite and oxalate

Titrimetric and spectrophotometric methods have been developed for the estimation of phosphite at mmole and mumole levels, respectively. Thallium(III) is used as an oxidant and the thallium(I) produced is determined either oxidimetrically with potassium bromate or by measurement of the absorbance of thallium(III) at 260 nm in the presence of 0.1 M hydrochloric acid and 1 M perchloric acid. Based on the fact that phosphite and oxalate are oxidized under different conditions, methods are described for the analysis of binary mixtures of phosphite and oxalate. A method is also described for estimation of thallium(III) with phosphite as reluctant, and is applied for analysis of mixtures of thallium(I) and thallium(III).     

Determination of thallium in geological materials by extraction and electrothermal atomic absorption spectrometry

Thallium is determined in geological reference materials by acid digestion, extraction of thallium(III) from 0.5 M HBr solution into methyl isobutyl ketone and direct electrothermal atomic absorption spectrometry. The method yields results that agree with published values, has a detection limit of 0.04 μg Tl g^-1, and is relatively free of interferences.     

Selective extraction of thallium(III) in the presence of gallium(III), indium(III), bismuth(III) and antimony(III) by salting-out of an aqueous mixture of 2-propanol

Thallium(III), in the presence of other triply charged ions such as gallium, indium, bismuth and antimony in aqueous solution, was quantitatively and selectively extracted into 2-propanol/water phase by addition of NaCl ranging from 2.5 to 4.0 mol dm⁻³. The extraction efficiencies of gallium, indium, bismuth and antimony were much lower than that of thallium(III). Thus a maximal selective separation of thallium(III) from these elements could be attained using a 2-propanol/water mixture. Thallium(III) was extracted as TlCl₄⁻ with Na⁺. The detailed extraction mechanism in the presence of chloride, water in the organic phase and counter ions is discussed.     

Thallimetric photochemical oxidation in titrimetric and spectrophotometric methods for the analysis of mixtures of oxalate and hydrogen peroxide

Thallium(III) in the presence of bromide photochemically oxidizes oxalate and hydrogen peroxide, whereas in the presence of a large excess of chloride, only oxalate is oxidized. Two procedures are based on these observations. In the titrimetric method (applied to mmol amounts of analytes) the thallium(I) formed is determined with bromate. In the spectrophotometric procedure (μmol amounts of analytes) unreduced thallium(III) is determined at 260 nm. In each case measurements are made after reaction under both conditions, so that both analytes can be determined.     

Die Kristallstruktur des „Thalliumdichlorids,TlCl2”︁

The Crystal Structure of Thallium Dichloride, TlCl₂ Thallium dichloride, TlCl₂, crystallizes tetragonal in the I4₁/a space group with cell constants a = 696.45(8) pm and c = 1 552.8(3) pm. The structure is of the CaWO₄ type so that the compound must be formulated as thallium(I)-tetrachlorothallate(III).     

Niobium(III) as an analytical reagent. : Part I. The titrimetric determination of iron,copper, thallium,molybdenum, uranium and vanadium

Niobium(III) solutions can be used in direct titrations of copper(II), iron(III), thallium(III), moIybdenum(VI), vanadium(V) and uranium(VI) in milligram amounts. Phenosafranine is generally satisfactory as the indicator, but potentiometric end-points can also be used. Copper and iron can be determined successively when a mixed indicator containing phenosafranine and méthylene blue is used. Thallium(I) and thallium (III) can be determined in mixtures. The niobium (III) solutions are stable for several days under a carbon dioxide atmosphere.