Tellurium Bromide Hydroxide

Diphenyl benzyl tellurium bromide,1 (CeH5)2(C6H5.CH2)TeBr, from diphenyl telluride dissolved in benzyl bromide, forms a crystalline mass, M.pt. 90° to 91° C., converted by silver hydroxide into the corresponding hydroxide, a yellow oil, very soluble in water, and yielding a sparingly soluble picrate on treatment with picric acid. 

Tri-p-tolyl tellurium iodide1 melts with decomposition at 232° to 233° C., dissolves readily in methyl alcohol or chloroform, less readily in benzene or ether, and is insoluble in water. Tri-p-tolyl tellurium bromide occurs when the iodide or chloride is boiled with silver bromide. It melts at 265° to 266° C. with decomposition, and dissolves in alcohols or chloroform, but is insoluble in benzene or ether. Tri-p-tolyl tellurium chloride is prepared from the bromide in the usual way. It melts at 260° to 261° C. and gives precipitates with the chlorides of mercury, tin and gold, picric acid and platinic chloride. The hydroxide is a resin, melting at about 110° C., and yielding a pier ate, consisting of long prisms, M.pt. 194° to 195° C.a... 

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°... 

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°. 

Acetylphenyl tellurium bromide condensed intramolecularly in ethanolic potassium hydroxide to yield 3-oxo-2,3-dihydrobenzotellurophene2,3. 

Oxo-2,3-dihydrobenzotellurophcnc2 5.0 g (15 mmol) of 2-acetylphenyl tellurium bromide is dissolved in 100 ml of ethanol, 0.85 g (15 mmol) of potassium hydroxide dissolved in ethanol are added, the mixture is stirred, and then poured into 200 ml of water. The precipitate is filtered ofT and rccrystallized from cyclohexane yield 3.0 g (80%) m.p. 107°. 

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. 

Dibutyl Ditellurium [Rongalite Method]9 Into a 500 ml three-necked flask are placed 9.24 g (0.08 mol) of Rongalite C, 9.0 g (0.23 mol) of sodium hydroxide, and 200 ml of water. The flask is flushed with nitrogen, 15.3 g (0.12 mol) of finely powdered tellurium are added, the stirred mixture is heated under reflux for 5 h under nitrogen, and then 16.4 g (0.12 mol) of butyl bromide are added dropwise. The mixture is then stirred for 30 min, allowed to cool, and extracted with three 100 ml portions of carbon tetrachloride. The combined extracts are dried with calcium chloride, the solvent is removed in vacuum under nitrogen, and the residue is fractionated under vacuum yield 5.1 g (23%) b.p. 112-11571-5 torr. 

Dialkyl Ditellurium (Thiourea Dioxide Method)2 A mixture of 128 mg (1.0 mmol) of elemental tellurium, 4 mg (0.01 mmol) of cetyltrimethylammonium bromide, 0.75 ml tetrahydrofuran, and 0.5 ml dimethyl sulfoxide is heated at 80° for 15 min under an atmosphere of deoxygenated nitrogen. To this mixture is added 100 mg (1.0 mmol) of thiourea dioxide, 112 mg (2.6 mmol) sodium hydroxide, and 0.75 ml water. The resulting mixture is refluxed for 1 h. The purple solution is then cooled to 15°. Alkyl halide (2.0 mmol) is added and the mixture is stirred at 20° for 1 h. After normal work-up, the dark-red oils were passed through a pad of Celite with dichloromethane as the mobile phase. 

Tellurium mixed with solid sodium hydroxide in dimethylformamide at 60° is reduced to disodium telluride by hydrazine hydrate4. However, neat hydrazine hydrate added to a slurry of tellurium in an aqueous solution of sodium hydroxide (6 M) produced only disodium ditelluride that was reduced to the telluride with sodium dithionite5. Addition of alkyl chlorides or bromides to these disodium telluride solutions gave dialkyl ditelluriums in good yields4,5. 

Dihydro-l//-2-benzotelliirin (Kongalite Method)2 34 g (0.17 mol) of sodium formaldehyde sulfoxylate, 26 g (0.65 mol) of sodium hydroxide, and 100 ml of water are placed in a flask fitted with a stirrer, a reflux condenser, and a nitrogen inlet tube. The flask is flushed with nitrogen, 15 g (0.12 mol) of fine tellurium powder is added, and the mixture is stirred and heated on a water bath for 30 min. 100 ml of ethanol and a solution of 25 g (0.09 mol) of 2-(2 -bromoethyl)benzyl bromide dissolved in 150 mi of hot ethanol are added. The mixture is stirred and heated under reflux for 2 h, the ethanol is distilled off, and the residue is ground, then extracted with a mixture of 300 ml of water and 300 ml of diethyl ether. The diethyl ether layer is separated, washed with water, dried with anhydrous sodium sulfate, filtered, and fractionally distilled yield 8.5 g b.p. 116-12670.3 torr. The residue from the extraction is boiled with 50 m/of ethanol, the mixture is filtered hot, and the filtrate allowed to cool. The crystals are collected (3.8 g) and the combined product fractions are recrystallized from methanol whereby the methanol solution is cooled in dry ice yield 12.3 g (54%) m.p. 64°. 

Bis[6-(tetrahydropyran-2-yl-oxy)-l-hexyl] Tellurium2 (Thiourea Dioxide Method) Under an atmosphere of nitrogen 200 mg (2 mmol) thiourea dioxide, 112 mg (2.6 mmol) sodium hydroxide, 0.75 mt water, 0.75 ml tetrahydrofuran and 128 mg (1 mmol) tellurium are mixed. The mixture is refluxed for 1 h. Then 2 mmol of the alkyl halide and 4 mg cetyltrimethylammonium bromide are added to the pale-pink solution.The mixture is refluxed for 1 h and then worked up in the usual way. The residue is purified by column chromatography on silica gel with petroleum ether as the mobile phase. The product is isolated in 72% yield. Similarly prepared were2 ... 

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. 

One Te-C bond in a diorgano tellurium can be cleaved by alkali metals, organic lithium compounds, sodium hydroxide, lithium aluminum hydride, sodium borohydride, Grignard reagents, tributyltin hydride, sulfuric acid, sodium sulfide, sulfuryl chloride, hydrogen bromide, bromine, or iodine. The Te-C bond can also be broken thermally or through photostimulation. 

The addition of a benzene solution of an alkyl chlorocarbonate to an aqueous solution of sodium tclluride (prepared from tellurium and Rongalite in an aqueous solution of sodium hydroxide) containing tetrabutylammonium bromide as a phase-transfer agent produced the bis[alkoxycarbonyl] tellurium at 20 . The reactions can also be carried out in dimethylformamide with sodium telluride obtained from sodium hydride and tellurium in dimethylformamide4... 

Bis[ethoxycarbonyl] Tellurium4 A mixture of 3.80 g (30 mmol) tellurium, 9.2 g (60 mmol) Rongalite, and 180 ml 1 M aqueous sodium hydroxide solution are stirred under an atmosphere of nitrogen at 60° for 2 h. The mixture is then cooled and 5 ml of an aqueous solution of tetrabutylammonium bromide (1.9 g, 6 mmol) are added. A solution of 9.1 g (84 mmol) ethyl chlorocarbonate in 100 ml benzene is added dropwise to the... 

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. 

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