Tellurium Formate Hydroxide

Water is without effect on the element even at a red heat,3 but the combined action of water and ozone produces telluric acid at the ordinary temperature.4 The action of hydrogen peroxide upon tellurium is influenced considerably by the physical state of the element colloidal tellurium is readily oxidised, but crystalline tellurium is not readily attacked and has first to be dissolved in an aqueous solution of alkali hydroxide, when oxidation becomes possible with formation of tellurate.5 Hydrogen peroxide of 60 per cent, strength reacts very slowly with tellurium at a temperature of 100° C., but with increasing amount of telluric acid formed, the rate of dissolution increases. Amorphous tellurium as ordinarily prepared behaves in a similar manner to the crystalline variety, but if it is dried by treatment with alcohol and ether instead of by heating at 105° C. it will dissolve readily in a concentrated solution of hydrogen peroxide.6... 

Hydrogen Telluride, H2Te.—In 1808 the observation was made by Ritter 1 that in the electrolysis of water using a tellurium cathode, an unstable tellurium-hydrogen compound was produced, and in repeating this experiment with potassium hydroxide solution as electrolyte, Sir Humphry Davy two years later further observed the formation of a deep red solution. Bcrthelot and Fabre in 1887 first prepared the hydrogen compound in a state approaching purity.2... 

Aqueous solutions of the alkali hydroxides readily dissolve tellurium dioxide with formation of the corresponding tellurite. In the presence of hydrogen peroxide the corresponding tellurate is formed.11 Ammonia and the alkali carbonates in cold aqueous solution have little effect, but the latter in hot solution or in the fused condition give rise to tellurites. Nitrates of the alkali metals on fusion with tellurium dioxide produce tellurates.12... 

A similar reaction with vinylacetylene in the absence of tin(II) chloride in a medium consisting of aqueous potassium hydroxide and DMSO gave bis[l,3-butadienyl] tellurium in 3% yield as a mixture of isomers with the cis-cis isomer as the predominant species3. The reaction of dilithium telluride with l,5-diphenyl-l,4-pentadiyn-3-one led to the formation of 2,6-diphenyl-4-oxo-4H-tellurin as the major product and of bis[1,5-diphenyl-3-oxo-5-ethoxypenta-l,4-dien-]-yl tellurium as a by-product5. 

The formation of ethenylphenyl tellurium in 20% yield from tellurium and acetylene at 100° in a system containing potassium hydroxide, tin(II) chloride, water, and hexamethylphos-phoric triamide in the presence of iodobenzene can be explained by the arylation of potassium ethenetellurolate, a likely intermediate in this reaction3. 

Alkyl and cycloalkyl halides react with benzenetellurolate to yield (cyclo)alkyl phenyl telluriums, which are converted to (cyclo)alkyl phenyl tellurium dibromides upon treatment with bromine. Stirring of a mixture of these tellurium dibromides and 0.5 M aqueous sodium hydroxide at 20° resulted in the formation of (cyclo)alkenes5. Alkyl phenyl tellurium oxides were postulated as intermediates that eliminated phenyl tellurium hydroxide. 

Treatment of aryl tellurium halides with base (ethanolic potassium hydroxide , aqueous sodium hydroxide, triethylamine , tris[(-propyl] phosphite , triphenylphosphane ) leads to the formation of diaryl ditellurium compounds (p. 273). In the hydrolytically induced disproportionation reactions, aryl tellurinic acids are the other tellurium-containing products ... 

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