Tellurium Acetate Hydroxide

Carboxybenzotellurophene A mixture of 15.5 g (53 mmol) of 2-formylphenyl car-boxymethyl tellurium, 50 niL of pyridine and 50 niL of acetic anhydride is heated under reflux for 2 h. Most of the solvent is then evaporated under vacuum, and the residue is extracted with boiling of 1 M aqueous sodium hydroxide solution. The extract is neutralized, the precipitate is filtered off and the solid is recrystallized from ethanol/benzene. Yield 11.6 g (80%) m.p. 206-208°C. 

Diphenyl tellurium hydroxybromide, (C6H5)2Te(OH)Br, may be obtained by treating the dibromide with water or the corresponding hydroxychloride with sodium or potassium bromide. It melts at 26-4° to 265° C., is moderately soluble in methyl alcohol but sparingly soluble in boiling water. Treatment with acetic acid yields the dibromide, and the mother-liquors from this give a substance which is probably the diacetate. The latter with 5 per cent, sodium hydroxide gives the oxide. 

Tellurium Tetrakis[bis(2-hydroxyethyl)dithlocarbamate]s 10 ml (0.1 mmol) of a freshly prepared 0.01 molar solution of bis[2-hydroxyethyl]dithiocarbamic acid in methanol are mixed with 10 ml of a 0.5 molar aqueous solution of sodium hydroxide containing 1.6 mg (0.01 mmol) of tellurium dioxide at 10°. 20 m/ of 1.0 molar aqueous acetic acid is added, the crystals that form within a few minutes are collected, washed repeatedly with cold diethyl ether, and recrystallized from acetone at 10-30°. 

Cs[(C2BqH11)2Co] are dissolved in 20 ml of acetic anhydride, 3.4 g (25 mmol) of powdered tellurium followed by 2 ml of concentrated sulfuric acid are added, and the mixture is heated at 100° for 4h, then filtered. Most of the acetic anhydride is removed from the filtrate at 80° (bath temperature)/10 torr. The residue is shaken with a mixture of 50 ml of water plus 50 ml of benzene, the aqueous layer is separated and discarded. The benzene is distilled under vacuum from the remaining non-aqueous phase, the residue is dissolved in 50 ml of acetone, and this solution is poured into 60 ml of methanol containing 6.0 g of potassium hydroxide. 2 ml of dimethyl sulfate are added, the mixture is shaken for 10 min, and excess dimethyl sulfate is removed by shaking the mixture with 10 ml of 15% aqueous ammonia. 50 ml of benzene and 200 ml of water arc added, the orange-colored benzene layer is separated, washed with two 50 ml portions of water, and filtered. The filtrate is concentrated to a volume of 10 ml, and poured onto a column containing 100 g of silica gel which is then eluted with benzene/hexane (1/1, v/v). The red band with Rt = 0.2 is separated mechanically, extracted with benzene, and the extract is concentrated to a volume of 10 ml. The viscous residue is covered with a layer of hexane and red needles separate overnight yield 0.15 g (3%). 

Aryl tellurium trihalides were hydrolyzed with aqueous sodium hydroxide solution. The tellurinic acids were precipitated by acidification of the reaction mixture with acetic, hydrochloric1 or sulfuric acid4. 

Z,Z)-Divinyl Tellurium4 To a stirred suspension of 0.383 g (3 mmol) tellurium in 15 ml ethanol kept under nitrogen are added in small portions 0.34 g (9 mmol) of sodium borohydride. The mixture is heated and 0.32 g (8 mmol) sodium hydroxide, 15 m/ water and 5 ml tetrahydrofuran arc added. The mixture is refluxed until all the tellurium has disappeared. When the refluxing mixture has turned yellow (3 to 6 h), it is cooled to 20°, diluted with 50 m/ethyl acetate, and washed with three 30-m/portions of a saturated aqueous solution of ammonium chloride and then with three 30-m/-portions of brine. The organic phase is separated, dried with anhydrous magnesium sulfate, and filtered. The solvent is evaporated from the filtrate on a rotary evaporator at 20 torr. The residue is flash-chromatographcd on silica gel with mixtures of hexane and ethyl acetate. 

Bis[4-methoxyphenyl] Tellurium Hydroxide Perchlorate1 3.58 g (10 mmol) of bis[4-methoxyphenyl] tellurium oxide is suspended in 7 ml of freshly distilled Iriethyl orthoformate. 1 ml (12 mmol) of 70% perchloric acid is added dropwise to the stirred suspension, whereupon the tellurium oxide dissolves. The mixture is stirred for 15 min and then 150 m/ of dry diethyl ether are added with continued stirring. The solvent is decanted from the colorless oil which is triturated with fresh portions of dry diethyl ether until it crystallizes. The crystals are filtered, washed with dry diethyl ether, dried, and recrystallized from acetic acid/diethyl ether yield 3.4 g (74%) m.p. 219°. 

The Te = N bond in diaryl tellurium sulfonimides is cleaved by boiling water, by boiling aqueous solutions of alkali hydroxides, by dry hydrogen chloride2, acetyl chloride, acetic anhydride or acetic acid in chloroform3. 

Tellurophene2 Sodium hydrogen telluride is prepared from 12.7 g (0.1 mol) tellurium and sodium in 150 ml dimethylformamide and the resulting solution cooled to 0°. A solution of 8.4 g (0.08 mol) of l-chloro-2-hydroxy-3-butyne in 20 ml ethanol is added dropwise during 30 min. The mixture is kept at 20° for 1 h and then treated with 5.6 g (0.1 mol) of powdered potassium hydroxide. The mixture is heated for 2 h at 100°, then cooled, treated with water, and extracted with diethyl ether. The extract is washed with water, dried, and concentrated. The residue is dissolved in a mixture of acetic acid/ethanol (1 8) (100 ml per 15 g) and the solution refluxed for 2 h. The mixture is then treated with water and extracted with diethyl ether. The extract is dried, filtered, and concentrated. The residue is distilled yield 10% b.p. 97/100 torr. 

When aryl tellurium trichlorides or tribromides were treated with aqueous solutions of sodium carbonate or sodium hydroxide and the resulting solutions acidified with 10% acetic add, tellurinic acid anhydrides precipitated. 

Alkyl Aryl Telluriums (Reduction with Thiourea Dioxide) To a solution of 1.0 mmol diaryl ditellurium in 7.5 ml tetrahydrofuran are added 0.108 g (1.0 mmol) thiourea dioxide, 30 mg 2HT (phase transfer reagent), and 2.0 mmol of the alkyl bromide. To this mixture are added 7.5 ml of a 50% aqueous solution of sodium hydroxide. The mixture is stirred for several hours at 20°. The organic phase is separated. The aqueous phase is extraeted three times with 20 ml ethyl acetate. The organic phase and the ethyl aeetate extracts are combined and dried with anhydrous magnesium sulfate. The mixture is filtered and the solvents evaporated from the filtrate. The residue is chromatographed on silica gel with ethyl acetate as mobile phase. 

Unsymmetrical Divinyl Tellurium 0.26 g (7.0 mmol) sodium borohydride is added in small portions to a solution of 2.5 mmol of the divinyl ditellurium, 0.56 g (14 mmol) sodium hydroxide in 10 m/ water and the acetylene in 15 m/ ethanol. The mixture is refluxed until the red color of the ditellurium has disappeared (30 min) and then 3 more hours. The mixture is cooled to 20°, treated with 20 ml of an aqueous saturated solution of ammonium chloride, and extracted with three 20-ml portions of ethyl acetate. The combined extracts are dried with anhydrous magnesium sulfate and then filtered. The solvent is removed from the filtrate in a rotary evaporator at 20 torr. The residue is flash-chromatographed on silica gel with hexane as the mobile phase. 

A,A-Dimethylaminothiocarbonyl Ethenyl Tellurium Under an argon atmosphere 6.38 g (50 mmol) of tellurium are added in one portion to 45.5 ml (23 mmol) of a 0.5 molar solution of vinylmagncsium bromide in tetrahydrofuran at — 78°. The mixture is stirred at — 78° for 1 h, warmed to 0°, and stirred at 0° for I h. The resultant yellowish-brown suspension is cooled to —78°, a solution of 6.18 g (50 mmol) of N,N-dimethylamino-(thiocarbonyl) chloride in 25 ml of tetrahydrofuran (freshly distilled from sodium) is added dropwise to the stirred suspension, and the mixture is stirred at — 78° for 0.5 h, at 0° for 1 h, and at 20" for 0.5 b. The mixture is then poured into ice/water and glacial acetic acid is added dropwise until the magnesium hydroxide has dissolved. The mixture is extracted three times with 150 ml portions of diethyl ether, the combined extracts arc washed three times with water, the ether solution is dried, and evaporated. The dcep-orange-red solid residue is the pure product yield 8.7 g (72%) m.p. < 25°... 

Carboxyphenyl carboxymethyl tellurium refluxed in acetic anhydride yielded 3-acet-oxybenzotellurophene, which, upon hydrolysis with potassium hydroxide, gave 3-hydr-oxybenzotellurophene. According to spectroscopic data, 3-hydroxybenzotellurophene exists in the form of 3-oxo-2,3-dihydrobenzotellurophene. This method of preparing 3-oxo-2,3-dihydrobenzotellurophene is laborious and gives low yields. ... 

Ultrapure PbO is made by precipitation from lead acetate solution by anunonium hydroxide in polyethylene vessels. In such wet preparations of lead(II) oxide, the yellow orthorhombic form is first produced which undergoes transformation to the red tetragonal PbO. This transformation is particularly sensitive to impurities, and the presence of elements such as silicon, germanium, phosphorus, arsenic, antimony, selenium, tellurium, molybdenum and tungsten in concentrations as low as 10 ppm prevents the transformation. The use of polythene vessels for the preparation of ultrapure red lead(II) oxide is emphasized, because sufficient silica is released from glass vessels to prevent the yellow to red con-versions s. ... 

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