Tellurides water

Heavy water, see Hydrogen[ H] oxide Heazlewoodite, see rn-Nickel disulfide Hematite, see Iron(III) oxide Hermannite, see Manganese silicate Hessite, see Silver telluride Hieratite, see Potassium hexafluorosilicate Hydroazoic acid, see Hydrogen azide Hydrophilite, see Calcium chloride Hydrosulfite, see Sodium dithionate(III)... 

Lead Telluride. Lead teUuride [1314-91 -6] PbTe, forms white cubic crystals, mol wt 334.79, sp gr 8.16, and has a hardness of 3 on the Mohs scale. It is very slightly soluble in water, melts at 917°C, and is prepared by melting lead and tellurium together. Lead teUuride has semiconductive and photoconductive properties. It is used in pyrometry, in heat-sensing instmments such as bolometers and infrared spectroscopes (see Infrared technology AND RAMAN SPECTROSCOPY), and in thermoelectric elements to convert heat directly to electricity (33,34,83). Lead teUuride is also used in catalysts for oxygen reduction in fuel ceUs (qv) (84), as cathodes in primary batteries with lithium anodes (85), in electrical contacts for vacuum switches (86), in lead-ion selective electrodes (87), in tunable lasers (qv) (88), and in thermistors (89). 

Most selenides and tellurides are decomposed by water or dilute acid to form H2Se or H2Te but the yields, particularly of the latter, are poor. 

A process for the gravimetric determination of mixtures of selenium and tellurium is also described. Selenium and tellurium occur in practice either as the impure elements or as selenides or tellurides. They may be brought into solution by mixing intimately with 2 parts of sodium carbonate and 1 part of potassium nitrate in a nickel crucible, covering with a layer of the mixture, and then heating gradually to fusion. The cold melt is extracted with water, and filtered. The elements are then determined in the filtrate. 

Selenic acid, H2Se04, is a strong acid (/fai 2) and the solubility of its salts parallels that of the corresponding sulfates. It is formed by the oxidation of selenous acid or elemental selenium with strong oxidizing agents in the presence of water. Telluric acid, H2Te04, or tellurates are obtained by oxidation of tellurides,... 

All the dialkali monosulfides are soluble in water and give alkaline solutions. The tellurides are instantly decomposed by air. They are soluble in water, but the solutions are easily oxidized to red polytellurides. The alkali metal tellurides are strong reducing agents which reduce tellurites to metallic tellurium. 

Ito, S., Toitani, N., Pan, L., Tamai, N. and Miyasaka, H. (2007) Fluorescence correlation spectroscopic study on water-soluble cadmium telluride nanocrystals fast blinking dynamics in the ps-ms region. J. Phys. Condens. Matter, 19, 486208. 

Sodium hydrogen telluride, (NaTeH), prepared in situ from the reaction of tellurium powder with an aqueous ethanol solution of sodium borohydride, is an effective reducing reagent for many functionalities, such as azide, sulfoxide, disulfide, activated C=C bonds, nitroxide, and so forth. Water is a convenient solvent for these transformations.28 A variety of functional groups including aldehydes, ketones, olefins, nitroxides, and azides are also reduced by sodium hypophosphite buffer solution.29... 

The final products of oxidation of diarylselenides and tellurides (and sulfides as well) in the presence of nucleophiles are the corresponding chalcogen (IV) compounds. In the presence of water, the selenoxide or telluroxide (or the corresponding dihydroxy selenane or tellurane) is the final product. This still leaves several possible pathways, leveraged from early mechanistic studies done using electrochemical techniques on diaryl sulfides and outlined by Engman (Fig. 32). In these pathways, the initial radical cation can react with a nucleophile present in solution, or the dication resulting from further oxidation or disproportionation can do so. 

The pure form of tellurium burns with a blue flame and forms tellurium dioxide (TeO ). It is brittle and is a poor conductor of electricity. It reacts with the halogens of group 17, but not with many metals. When it reacts with gold, it forms gold telluride. Tellurium is insoluble in water but readily reacts with nitric acid to produce tellurous acid. If inhaled, it produces a garlic-like odor on one s breath. 

Reaction of diarylditellurides with arenediazonium salts (typical procedure). p-Methoxy phenyl p-tolyl telluride. With heating and stirring in an atmosphere of nitrogen, sodium tetrahydroborate was added in small portions to a solution of 9.4 g of bis(p-methoxyphenyl) ditelluride in a mixture of 50 mL of ethanol and 15 mL of benzene until the solution was decolourized completely (1.5 g was required). Then 8.24 g of p-toluenediazonium fluo-roborate was added rapidly and the mixture was stirred for 1 h and poured into dilute HCl. The oil formed was extracted with ether, and the extract was washed with water and dried over CaCl2. Ether was evaporated, and the residue was dissolved in benzene and chromatographed on alumina (eluent hexane). After the evaporation of hexane, 4.8 g (36%) of the telluride was isolated, m.p. 64-64.5°C (hexane). 

Reduction of diaryltellurium dichlorides with sodium ascorbate (typical procedure). Bis (p-methoxyphenyl)tellurium dichloride (0.20 g, 0.48 mmol) dissolved in acetone (10 mL) was added to a stirred solution of sodium ascorbate (0.20 g, 1.0 mmol) in water/methanol (2+8 mL). After 24 h, water (50 mL) and CH2CI2 (50 mL) were added and the two phases separated. The organic phase was dried (CaCl2) and the solvent evaporated in vacuo. Flash chromatography yielded 0.14 g (84%) of bis(p-methoxyphenyl) telluride. 

Water-soluble diorganyl tellurides with thiolperoxidase and autoxidant activity have been prepared as depicted in the following scheme. ... 

The yields were markedly increased by the addition of a reducing agent such as SnCl2." The reaction of elemental Te, phenylacetylene, KOH in hydrazine hydrate/ water/toluene was performed under three-phase catalytical system (in the presence of AlKjN+MeCr) giving (Z,Z)-distyryl telluride in 50% yield. ... 

Reaction ofvinylacetylene with Te-KOH-DMSO triad A mixtnre of Te (25.9.), KOH (20 g), H2O (10.9 mL) and DMSO (100 mL) was heated (110°C) with vinylacetylene (31.7 g) in 1 L steel-rotating autoclave for 3 h. The reaction mixtnre was ponred into water, and extracted with Et20. The extracts were washed with H2O. The solvent was stripped off and the residne was distilled in vacuum to collect the rnn with b.p. 80-86°C (2.2 g) consisting of bis(l,3-butadienyl) telluride (1.1 g). 

Reaction of phenylacetylene with Te/KOH/SnCf A mixtnre of 6.4 g of tellurium, 42 g of potassium hydroxide, 22.6 g of SnCl2 2H20, 10.2 g of phenylacetylene, 20 mL of toluene, 60 mL of water and 1.2 g of Adogen 464 was heated (80-97°C) with vigorous stirring for 7 h. The organic layer was separated, and the aqneons layer was extracted with benzene. The benzene was removed under vacnnm. The residne was dissolved in a small amount of ether, poured into 200 mL of isopropyl alcohol, and placed in the refrigerator for 3 days. The yellow crystals of distyryl telluride (2.5 g, yield 15%) and the red needle crystals of distyryl ditelluride (0.7 g, yield 6%) were separated. 

Reaction of phenylacetylene with Te/K0H/N2HfXH20f (Z,Z)-distyryl telluride. A mixture of Te (12.8 g), phenylacetylene (20.4 g), KOH (84 g), NjH XHjO (120 mL), H2O (24 mL), toluene (40 mL), and AlKjN MeCl (1 g) was heated (100-110°C) with a stirring of 6 h. The mixtnre was dilnted with water and extracted with benzene. The organic layer was washed with water, dried over K2CO3 and evaporated. The residue was dissolved in ether, the ether solntion was ponred into ethanol and put into refrigerator. After several days yellow cristals of the tellnride (16.7 g, 50% yield) were separated and dried. 

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