Thallium III oxide

Both the submitters and the checkers used thallium(III) tri-fluoroacetate prepared from thallium(III) oxide and trifluoroacetic acid.3 Although this material may be purchased from Aldrich Chemical Company, Inc. and Eastman Organic Chemicals, the submitters recommend that the reagent be freshly prepared prior to use. 

The reaction mixture first turns muddy brown, due to the hydrolysis of thallium(III) nitrate to thallium(III) hydroxide and thallium(III) oxide, and then yellow with the separation of colorless thallium(I) nitrate. 

Littler has studied the oxidation of cyclohexanone with lead(IV), thallium(III), and mercury(II) salts (84), and found that, with all three reagents the rates of oxidation are independent of the concentration of oxidant. Oxidation by thallium(III) and mercury(II) in 35% aqueous perchloric acid showed first-order dependence on [H" ], and Littler suggested that the results were best interpreted in terms of the reaction sequence shown in Scheme 27. The major product of thallium(III) oxidation of... 

Hydrogen sulfide is rapidly oxidised, and may ignite in contact with a range of metal oxides, including barium peroxide, chromium trioxide, copper oxide, lead dioxide, manganese dioxide, nickel oxide, silver(I) oxide, silver(II) oxide, sodium peroxide, and thallium(III) oxide. In the presence of air, contact with mixtures of calcium oxide or barium oxide with mercury oxide or nickel oxide may cause vivid incandescence or explosion. 

Sodium peroxide Non-metals Thallium(III) oxide Sulfur... 

Sodium trioxide, 4800 Tantalum(V) oxide, 4865 Thallium(III) oxide, 4854... 

Method A A solution of 0.5 mmol of (2/ /S ,3R/S )-2,3-dialkyl-1,4-diarylbutane and 0.125 mL (1.0 mmol) of boron trifluoride-diethyl ether complex in 2 mL of trifluoroacctic acid is added to a suspension of 0.12 g (0.26 mmol) of thallium(III) oxide in 2 mL of trifluoroacetic acid at — 40°C to +25CC under an argon atmosphere. The dark colored solution is stirred until the reaction is complete, diluted with ethyl acetate, then washed successively with water (twice) and sat. aq NaCl. Evaporation of the dried extract gives the crude product. In a variant of this method the boron trifluoride-diethyl ether complex can be omitted. 

Table 1. Intramolecular Stereoselective Aryl Coupling with Thallium(III) Oxide/Trifluo-roacetic Acid (Method A)...

Sulfonation. Sulfonation is a common reaction with dialkyl sulfates, either by slow decomposition on heating with the release of S03 or by attack at the sulfur end of the O—S bond (63). Reaction products are usually the dimethyl ether, methanol, sulfonic acid, and methyl sulfonates, corresponding to both routes. Reactive aromatics are commonly those with higher reactivity to electrophilic substitution at temperatures > 100° C. Thphenylamine, diphenylmethylamine, anisole, and diphenyl ether exhibit ring sulfonation at 150—160°C, 140°C, 155—160°C, and 180—190°C, respectively, but diphenyl ketone and benzyl methyl ether do not react up to 190°C. Diphenyl amine methylates and then sulfonates. Catalysis of sulfonation of anthraquinone by dimethyl sulfate occurs with thallium(III) oxide or mercury(II) oxide at 170°C. Alkyl interchange also gives sulfation. 

Production and Economic Aspects. Thallium is obtained commercially as a by-product in the roasting of zinc, copper, and lead ores. The thallium is collected in the flue dust in the form of oxide or sulfate with other by-product metals, eg, cadmium, indium, germanium, selenium, and tellurium. The thallium content of the flue dust is low and further enrichment steps are required. If the thallium compounds present are soluble, ie, as oxides or sulfates, direct leaching with water or dilute acid separates them from the other insoluble metals. Otherwise, the thallium compound is solubilized with oxidizing roasts, by sulfatization, or by treatment with alkali. The thallium precipitates from these solutions as thallium(I) chloride [7791-12-0]. Electrolysis of the thallium(I) sulfate [7446-18-6] solution affords thallium metal in high purity (5,6). The sulfate solution must be acidified with sulfuric acid to avoid cathodic separation of zinc and anodic deposition of thallium(III) oxide [1314-32-5]. The metal deposited on the cathode is removed, kneaded into lumps, and dried. It is then compressed into blocks, melted under hydrogen, and cast into sticks. 

Thallium (TIT) salts of formic, acetic, and trifluoroacetic acids are prepared from the corresponding acid and thallium(III) oxide (11). Other thallium(III) carboxylates can be obtained from the metathesis of thallium(III) acetate and the carboxylic acid (12). They are colorless, hygroscopic solids. 

Thallium(III) fluoride has been prepared by the action of fluorine or bromine trifluoride on thallium(III) oxide at 300°C. It is stable to ca 500°C but is extremely sensitive to moisture. Thallium(III) chloride can be obtained readily as the tetrahydrate [13453-33-3] by passing chlorine through a boiling suspension of HC1 in water. It can be dehydrated with thionyl chloride. Thallium(III) bromide tetrahydrate [13453-29-7] is prepared similarly, whereas the iodide prepared in this manner is thallium(I) triiodide [13453-37-7], H+Iy. 

Thallinm(III) chloride (0 2m). Dissolve 45-7 g thallium(III) oxide, T1203, in 50 ml of 1 1 hydrochloric acid. Evaporate the solution to dryness and dissolve the residue in water. Dilute the solution to 1 litre. 

Thallium(III) oxide is a degenerate n-type semiconductor (see Semiconductors) with a Band Gap of 1.4 eV, and it shows electronic and optical properties, which make it useful in applications such as solar cells and electrical contacts. The interest in thallium oxide has been further stimulated by the discovery that the system Tl-Ca-Ba-Cu-O represents a... 

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