Tellurium hydrogen compounds

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... 

However, selenium and tellurium do not react with hydrogen, so the hydrogen compounds are prepared by reacting the elements with a metal, then treating it with an acid. Selenium and tellurium undergo addition reactions with cyanides to yield selenocyanates and tellurocyanates ... 

Hydrogen peroxide oxidizes the tellurium-bridged compound to arsanthrenic acid3. 

The telluronoamides and telluronohydrazides are stable at 20° in the absence of moisture. Wet solvents or moisture cause elimination of tellurium. The compounds cannot be chromatographed on alumina or silica gel1. The telluronodimethylformamide obtained from cholesteryloxymethylene iminium chloride and sodium hydrogen telluride is a yellow, unstable solid2. 

TELLURIUM and COMPOUNDS (as Te) (Tellurium compounds have variable molecular formulas. The molecular formula for tellurium is Te. The molecular formulas for hydrogen telluride and potassium tellurite are H2Te and KaTeOs, respectively. Tellurium compounds have variable formula weights. The formula weight for tellurium is 127.60. The formula weights for hydrogen telluride and potassium tellurite are 129.6 and 253.8, respectively.)... 

SPILL CLEAN-UP ventilate area of spill or leak sweep spilled substance into sealed containers for disposal in a designated landfill absorb liquid containing tellurium and compounds with noncombustible materials (e.g., dry earth, sand, or vermiculite) for hydrogen telluride, stop flow of gas if possible if source of leak is a cylinder, cautiously remove leaking cylinder to a safe place in open air, and allow cylinder to empty. 

Tellurium and compounds (as Te) Complaints of sleepiness, nausea, metallic taste, and garlicky odor on breath and perspiration associated with workplace exposures. Neuropathies have been noted in high-dose studies. Hydrogen telluride causes pulmonary irritation and hemolysis however, its ready decomposition reduces likelihood of a toxic exposure. Some tellurium compounds are fetotoxic or teratogenic in test animals. 0.1 mg/m (as Te) 25 mg/m (as Te) Metallic tellurium Is a solid with a sllveiy-whlte or grayish luster. 

Hydride generation in AAS became popular after 1970 in response to a study by Holak, which demonstrated the analytical potential of this approach for arsenic. Since then, elements of groups IVA, VA, and VIA of the periodic table have been shown to form volatile covalent hydrogen compounds with sufficient efficiency to be of practical analytical use. These include arsenic, bismuth, germanium, lead, antimony, selenium, tin, tellurium, and to some extent, indium and thallium. 

Hydrogenation Catalysts. The key to catalytic hydrogenation is the catalyst, which promotes a reaction which otherwise would occur too slowly to be useful. Catalysts for the hydrogenation of nitro compounds and nitriles are generally based on one or more of the group VIII metals. The metals most commonly used are cobalt, nickel, palladium, platinum, rhodium, and mthenium, but others, including copper (16), iron (17), and tellurium... 

Elemental tellurium and the stable teUurides of heavy nonferrous metals are relatively inert and do not represent a significant health hazard (43—47). Other, more reactive teUurides, including soluble and volatile teUurium compounds such as hydrogen teUuride [7783-09-7] teUurium hexafluoride [7783-80-4] and alkyl teUurides, should be handled with caution. Some of these materials can enter the body by absorption through the skin or by inhalation and ingestion of dust or fumes. No serious consequences or deaths have been reported in workers exposed to teUurium and its compounds in industry (48). 

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 alkaU. The thallium precipitates from these solutions as thaUium(I) chloride [7791 -12-0]. Electrolysis of the thaUium(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 thaUium(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. 

Caution Because tellurium compounds have toxic effects similar to those of arsenic compounds care should be taken not to bring tellurium tetrachloride and its reaction products into contact with the skin. Avoid breathing fumes and dust of tellurium compounds. In addition, hydrogen chloride is evolved in Step A, and pyrophoric Raney nickel is used in Step B. Therefore all manipulations described in this procedure must be carried out in an efficient fume hood. 

Tellur-verbindung, /. tellurium compound, -vorlegierung,/. tellurium prealloy, -wasser-stoff, m. hydrogen telluride. -wasserstoff-sSure, /. hydrotelluric acid (hydrogen telluride). -wismut, n. bismuth telluride. 

The stability of chalconide (ionic) compounds decreases from oxygen to tellurium treatment with water produces XH- with X = O or S (hydroxyl and thiol radicals, respectively), but XH2 with X = Se or Te. On warming, aqueous solutions of HS evolve hydrogen sulfide, evidencing that the hydrosulfide ion is much less stable than hydroxide. 

Wolfolk CA, Whiteley HR. 1962. Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyicus. I. Stoichiometry with compounds of arsenic, selenium, tellurium, transition and other elements. J Bacteriol 84 647-58. 

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