Tellurium potassium bromide

Lenher 6 determined the atomic weight of tellurium by decomposing weighed amounts of potassium telluribromide, K2TeBr6, by means of chlorine and hydrogen chloride, and weighing the potassium chloride which remained. Using tellurium ores from three different sources, the oxide obtained was converted into the double bromide by the action of hydrobromic acid and potassium bromide the telluribromide formed was crystallised repeatedly from water. As a mean of sixteen concordant experiments Lenher obtained the value 127-55. 

Tellurium dioxide may be converted into the tetrabromide by means of hydrobromic acid or a mixture of potassium bromide and phosphoric acid in aqueous solution.3... 

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 bis[bis(2-hydroxyethyl)dithiocarbamate] and a thirty-fold molar excess of potassium bromide, iodide, or thiocyanate reacted in acetone acidified with acetic acid with replacement of one dithiocarbamate group per two molecules of tellurium dithiocarbamate by halide or thiocyanate. The deep-red crystals are stable as solids but decompose with deposition of tellurium when dissolved in methanol. The single-crystal X-ray structural analysis of the thiocyanato derivative revealed the presence of two chemically different tellurium atoms in the molecule that are in short contact1. 

Chloro-4-hydroxyphenyl Tellurium Tribromide (Triiodide)2 To a saturated solution of 1.0 g (2.8 mmol) of 3-chloro-4-hydroxyphenyl tellurium trichloride in 10 ml of methanol is added a solution of 1.2 g (10 mmol) of potassium bromide [or 1.7 g (10 mmol) of potassium iodide] in 30 ml of methanol. The solution darkens immediately and deposits potassium chloride 50 m/ of diethyl ether are added to precipitate additional potassium chloride and unreacted potassium bromide (or iodide). The mixture is filtered and the filtrate is concentrated under vacuum until the product crystallizes. 

Treatment of aryl tellurium trichlorides with silver fluoride, potassium bromide, or potassium iodide causes chlorine to be exchanged for other halogens (see p. 320). The reaction of 4-ethoxyphenyl tellurium trichloride with silver acetate gave a compound of indefinite composition6. 

Refluxing diaryl tellurium dichlorides with potassium bromide in dioxane1 or methanol2 gave diaryl tellurium dibromides in almost quantitative yields. 

Bis[4-methylphenyl Phenyl Tellurium Bromide] Oxide1 1.5 g (4.3 mmol) of 4-methylphenyl phenyl tellurium hydroxide chloride (or dichloridc) are dissolved in water and potassium bromide is added. The precipitate is collected and recrystallized from 600 ml of water m.p. 260°. 

Whether hydrolytic reactions of diorgano tellurium halides produce diorgano tellurium hydroxide halides or their anhydrides might be governed by the solubility of the anhydride, which is influenced by the halide. Treatment of the solutions obtained by boiling mixtures of diaryl tellurium dichlorides and water or treatment of aqueous solutions of diaryl tellurium hydroxide chlorides with potassium bromide or potassium iodide formed bis[diaryl tellurium halide] oxides. 

Volumetrically tellurium may be determined by several methods (1) Tellurous acid is oxidized to telluric by permanganate either in acid solution 3 or alkaline solution.4 (2) Tellurous acid in hydrochloric acid solution is reduced by an excess of standard stannous chloride, according to the reaction TeCl< + 2 SnCU — Te + 2 SnCL. The excess stannous chloride is determined iodometrically.5 (3) Telluric acid may be reduced to tellurous by the use of potassium bromide in sulfuric acid solution, thus H2TeO< + 2 HBr = H2TeO + H20 + Br2. The bromine is distilled into a solution of potassium iodide, the liberated iodine being determined by standard thiosulfate.6... 

The first synthesis of dibenzotellurophene was accomplished by Courtot and Bastani90 by treating diphenyl (39) with tellurium tetra-bromide or tetrachloride and then reducing the adduct (40) with potassium hydrogen sulfite [Eq. (8)]. 

Tellurium dioxide (0.5 g.) is dissolved in 5 ml. of 40 per cent hydrobromic acid. A saturated solution of two molal equivalents of potassium bromide (0.75 g. in about 1.4 ml. of water) is then added. The solution is evaporated on a steam bath and stirred until the orange crystals settle well. The salt is recrystalhzed from boiUng water containing 5 to 10 per cent hydrobromic acid and is dried in a vacuum desiccator over soda lime and finally over sulfuric acid. Yield 1.60 g. (75 per cent). 

See Ammonium nitrate Metals Chlorine Metals Chlorine trifluoride Metals Copper(II) nitrate Tin Fluorine Metals Iodine bromide Metals Iodine heptafluoride Metals Potassium dioxide Metals Sodium peroxide Metals Sulfur Metals Tellurium Tin... 

In 1858 von Hauer 6 prepared and analysed the double bromide of potassium and tellurium, K2TeBr6, and obtained the value 127-8. 

Ditellurium Tris[bis(2-hydroxyethyl) dithiocarbamate] Thiocyanate1 31 mg (0.1 mmol) of tellurium bis[bis(2-hydroxycthyl)dithiocarbamate] are dissolved in 5 ml of acetone. A solution of 0.29 g (3 mmol) of potassium thiocyanate in 10 ml of 3 M acetic acid is added. The reaction mixture is stirred and kept in a Petri dish at room temperature. Over night, deep-red, needle-shaped crystals separated. The crystals are filtered, washed with 1 M acetic acid and then with diethyl ether, and finally dried over anhydrous calcium chloride yield 80% dec. > 100° (TGA). The bromide and iodide derivatives were similarly prepared in the same yield. 

Refluxing a solution of 2-formylphenyl tellurium bromide, hydroxylaminc hydrochloride, and potassium acetate in absolute ethanol produced the corresponding oxime2. 

Ethoxycarbonylbenzyl Tellurium Cyanide3 A dark colored solution of 0.52 g (1.28 mmol) of 2-bromocarbonylbenzyl tellurium bromide in 10 m/ of ethanol is added dropwise to a suspension of 0.30 g (4.6 mmol) of potassium cyanide in 5 ml of DMSO. The resultant yellow solution is stirred for 30 min and then poured into a mixture of 50 ml water/50 ml diethyl ether. The organic phase is separated, extracted several times with water, and dried with anhydrous calcium chloride. The diethyl ether is evaporated and the oily residue crystallizes on standing yield 0.28 g (69%) m.p. 72-73J (carbon tetrachloride/hexane). Similarly prepared was ... 

Ethyl Vinyl Tellurium2 A mixture of 2.8 g (22 mmol) tellurium, 1.1 g (10 mmol) ethyl bromide, 48.7 g (868 mmol) potassium hydroxide, 24.7 g (130 mmol) tin(II) chloride, and 150 ml water are heated in a 1 -l rotating autoclave under an acetylene pressure of 15 atm for 5 h at 105-115c. The lower organic layer is separated from the reaction mixture, dried with potassium hydroxide, and fractionated at 1 torr. According to GLC data, the material collected in a trap cooled at — 70° contains 1.27 g (7%) ethyl vinyl tellurium, 10 g (55%) divinyl tellurium, and 0.11 g (6%) diethyl tellurium. Ethyl vinyl tellurium boiled at 138 7720 torr. 

Because diaryl tellurium diiodides are not hydrolyzed by boiling water, the diaryl tellurium hydroxide iodides were prepared by treating the hydroxide chlorides or bromides with potassium iodide1. 

Diphenyl Tellurium Hydroxide Iodide1 Diphenyl tellurium chloride (or bromide) hydroxide is dissolved in water and a slight excess of potassium iodide dissolved in water is added. The yellow precipitate is filtered off and recrystallizcd from methanol. For dissolution of the product in methanol, the mixture is heated cautiously on a water bath to prevent the hydroxide iodide from disproportionating to the diiodide and the dihydroxide (or oxide). The pure product has m.p. 215°... 

Diaryl tellurium dihalides in toluene solutions reacted with aryl magnesium bromides in diethyl ether to yield triaryl telluronium salts in yields ranging from 6 to 78% (Vol. IX, p. 1082/3)3-5. Aqueous solutions of the products were generally treated with potassium iodide to convert the telluronium halides to telluronium iodides3,4. 

Diphenyl Naphthyl Telluronium Iodide1 10 g (28 mmol) of diphenyl tellurium dichloridc are dissolved in 250 ml of dry toluene. A solution of 1 -naphthyl magnesium bromide in diethyl ether is prepared from 17.4 g (84 mmol) of 1-bromonaphthalene. The solution of the tellurium compound is quickly poured into the freshly prepared Grignard solution, the mixture is shaken vigorously, and 20 ml of dilute hydrochloric acid are added immediately. The solution is decanted from the precipitate, the precipitate is dissolved in boiling water, silver chloride is added, and the mixture is heated. The mixture is then filtered, sodium sulfite is added to the filtrate, and the telluronium iodide is precipitated by the addition of potassium iodide yield 11.8 g (78%) m.p. 148° (from ethanol, ethanol/diethyl ether). 

When treated with potassium iodide, hot, aqueous solutions of triaryl telluronium chlorides precipitate triaryl telluronium iodides1 (Vol. IX, p. 1080). This halogen exchange reaction was used to isolate triaryl telluronium compounds from the mixtures obtained by reacting tellurium tetrachloride with aryl magnesium bromides (Vol. TX, p. 1080). 

Diorgano alkyl telluronium bromides were converted to diorgano alkylidene telluriums on treatment with potassium tert.-butoxide2 (see p. 718). 

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