Tellurium sulfate

Basic tellurium sulfate 2 Te02 S03 [12068-84-8]-, 2 Te02 Se03 selenate and tellurate, 2 Te02 Te03, are known. The sulfate is made by the slow evaporation of a Te02 solution in H2S04. It is stable up to 440—500°C and is hydrolyzed slowly by cold, and rapidly by hot water. 

Diorgano tellurium bis[hydrogen sulfates] are not well characterized. The few dialkyl tellurium sulfates reported were obtained from dialkyl tellurium dihydroxides and sulfuric acid1,2. 

Tellurium dioxide complexes with thiourea, 305 Tellurium dithiocyanate complexes, 303 Tellurium hexafluoride complexes, 303 with amines, 304 Tellurium sulfate complexes, 303 Tellurium tetrabromide complexes, 302 Tellurium tetrachloride complexes with acetamide, 304 with amines, 304 with pyridine N-oxide, 304 Tellurium tetrafluoride complexes with amines, 304 with dioxane, 304 Tellurotungstates, 1042 Tempera ture-jump studies molybdenum(VI) complexes, 1259 Terbium complexes p diketones, 1081... 

It is perceptibly soluble in water to give a neutral solution. It is soluble both in sodium hydroxide solutions and in hydrochloric acid. It is converted into a basic tellurium sulfate by heating to the appearance of white fumes with sulfuric acid. 

Sulfation Roasting. Acid roasting technology (Fig. 2) rehes on differences in the volatiUty of the tetravalent oxides of selenium and tellurium at roasting temperatures of 500—600°C to selectively volatilise selenium from slimes. Acid roasting uses sulfuric acid as the oxidant for the conversion of selenium/selenides and tellurium/teUurides to their respective tetravalent oxides. Typical oxidation reactions are as foUow ... 

It is apparent from these equations that significant quantities of sulfur dioxide are generated. For selenium, the reaction shown for oxidation of elemental selenium reverses itself at the lower temperatures employed for water scmbbing, thus regenerating sulfuric acid. The tellurium dioxide remains in the sulfated slimes. 

Although gravimetric methods have been used traditionally for the determination of large amounts of tellurium, more accurate and convenient volumetric methods are favored. The oxidation of teUurium(IV) by ceric sulfate in hot sulfuric acid solution in the presence of chromic ion as catalyst affords a convenient volumetric method for the determination of tellurium (32). Selenium(IV) does not interfere if the sulfuric acid is less than 2 N in concentration. Excess ceric sulfate is added, the excess being titrated with ferrous ammonium sulfate using o-phenanthroline ferrous—sulfate as indicator. The ceric sulfate method is best appHed in tellurium-rich materials such as refined tellurium or tellurium compounds. 

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. 

The checkers distilled the anisole from calcium sulfate before use. This reagent functions not only as a reactant, but also as solvent. In some similar preparations the intermediate trichloride is rather insoluble, as in the case of bis(3-methyl-4-methoxyphenyl)tellurium dichloride. The addition of co-solvents such as bis-(2-methoxyethyl) ether is beneficial. ... 

The possibility that adsorption reactions play an important role in the reduction of telluryl ions has been discussed in several works (Chap. 3 CdTe). By using various electrochemical techniques in stationary and non-stationary diffusion regimes, such as voltammetry, chronopotentiometry, and pulsed current electrolysis, Montiel-Santillan et al. [52] have shown that the electrochemical reduction of HTeOj in acid sulfate medium (pH 2) on solid tellurium electrodes, generated in situ at 25 °C, must be considered as a four-electron process preceded by a slow adsorption step of the telluryl ions the reduction mechanism was observed to depend on the applied potential, so that at high overpotentials the adsorption step was not significant for the overall process. 

Tellurium Tetrahydrofuran Tetranitroaniline Tetranitromethane Thiocyanates Thionyl chloride Thiophene Thymol Halogens, metals Tetrahydridoaluminates, KOH, NaOH Reducing materials Aluminum, cotton, aromatic nitro compounds, hydrocarbons, cotton, toluene Chlorates, nitric acid, peroxides Ammonia, dimethylsulfoxide, linseed oil, quinoline, sodium Nitric acid Acetanilide, antipyrine, camphor, chlorohydrate, menthol, quinine sulfate, ure- thene... 

Ceric ammonium sulfate, 5 674 Ceric fluoride, 5 674 Ceric hydroxide, 5 676 Ceric oxide, 5 670, 675 Ceric rare earths (RE), 74 631 Ceric sulfate, 5 674 Ceric sulfate method, for tellurium determination, 24 415 Cerium (Ce), 5 670-692 74 630, 63 It, 634t. See also Cerium compounds analysis, 5 679-680 color, 7 335... 

Hydrazine sulfate is used as a reducing agent in analytical chemistry for gravimetric measurement of nickel, cobalt, and other metals, and in peptide analysis in the separation of polonium from tellurium as an antioxidant in... 

An acidic solution of tellurium (IV) or tellurium (VI) is treated with sulfur dioxide and hydrazine hydrochloride. Tellurium precipitated from solution can be estimated by gravimetry. Selenium interferes with this test. A volumetric test involves converting tellurium to tellurous acid and oxidizing the acid with excess ceric sulfate in hot sulfuric acid in the presence of Cr3+ ion as catalyst. The excess ceric sulfate is measured by titration with a standard solution of ferrous ammonium sulfate. 

Electrodeposition and stripping of tellurium and CdTe in sulfate electrolyte was studied by voltammetric and electrogravi-metric experiments [206]. 

The basic salts of quadrivalent polonium, such as the sulfate and sele-nate, show a marked resemblance to those of tellurium and further resemblances appear in the quadrivalent halides, particularly in their complexing with halide ions in solution, while complexing of polonium(IV) with weak acids, such as acetic, oxalic and tartaric, seems to be more marked than is the case with tellurium. 

Tellurium Bis[dithioacetatcl (Preparation in Water/Dichloromcthanc)1 A solution of 4.4 g (25 mmol) of piperidinium dithioacetate in 100 ml of dichloromethane is added dropwise to a solution of 6.0 g (15 mmol) of disodium tellurapentathionate in 150 ml of water and the mixture is stirred at 18° for 10 min. The organic phase is then separated, dried with anhydrous magnesium sulfate, filtered, and the solvent is evaporated from the filtrate under reduced pressure. The residue is washed with 5 ml of methanol yield 3.9 g (83%) m.p. 130 (dec.). 

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