Dimethyl telluride

Preparation of alkylvinyl tellurides by reaction of Te/KOH/alkyl iodides, SnCf in HMPA/H2O with pressurized acetylene. Methylvinyl telluride. 12.8 g of Te, 1.42 g of methyl iodide, 48.7 g KOH, 24.7 g SnCl2, 80 mL HMPA and 70 mL HjO were heated (105-115°C) in a rotating autoclave 1 L under acetylenic pressure (initial pressure 14 atm, residual pressure 7 atm, absorbed acetylene 0.8 mol) tor 5 h. The reaction mixture is evacuated at 1 mmHg. The fraction (10.5 g) collected into a cooled trap (-70°C) contains, according to GLC data, methylvinyl telluride (0.34 g, yield 20%), divinyl telluride (10 g, yield 55%) and dimethyl telluride (0.12 g, yield 8%) b.p. 115-116°C. 

Dimethyl telluride, (CH3)2Te.—The method first used for isolating this substance consisted in treating a potassium-tellurium alloy with a concentrated aqueous solution of barium methyl sulphate.1 It appears doubtful whether the method can actually be used for obtaining dimethyl telluride itself, although it might be used for derivatives of this body. An excellent yield of dimethyl telluride is obtained according to the equation 2... 

Drew (J. Chem. Soc., 1929, p. 568) considers that the /5-dihalides do not give dimethyl telluride on reduction, but an orange oil of carbylamine odour, probably dimethyl ditelluride. 

Trimethyl tellurium iodide, (CH3)3TeI,4 may be prepared by treating the dimethyl di-iodide with sodium sulphite and methyl iodide, or by reducing the di-iodide to dimethyl telluride and treating the latter with methyl iodide. The most recent method of preparation... 

The dimethyltelluronium ion Me2TeH+ (protonated dimethyl telluride) shows the methyl doublet at 8 H 2.7 (/ = 7Hz) and the septet at 81 H 1.6. Similarly, the diethyltelluronium ion Et2TeH+ (protonated diethyl telluride) shows the methyl triplet at 81 H 1.9, the methylene quintet at 8 H 3.4, and the multiplet, partially overlapping the methyl triplet at 8 H 1.6. 

Biomethylation. Methylation and methyl transfer are important reactions in the organic metabolism of organisms (Mudd, 1973) and it has been known for some time that dimethyl selenide, dimethyl telluride and di- and trimethyl arsine are biosynthetic products of the metabolism of inorganic compounds selenium, tellurium and arsenic, respectively, by microorganisms (Challenger, 1951). 

Besides the atomic reactions of the group 16 elements such as oxygen, sulfur, and the previously mentioned selenium, the reactions of tellurium atoms with alkenes have also been reported. In the case of tellurium, the ultraviolet photolysis of dimethyl telluride (DMT) is a usable source of 3P2j0 tellurium atoms (69PCS304). In flashed mixtures of DMT vapor (10—3 10 1 torr with COz diluent) using kinetic absorption spectroscopy, intense absorptions at 2143 2259 A, which correspond to known transitions of Te(3i>2), and at 2386 and 2383 A corresponding to Te(3/)1) and (VJ0), respectively, were observed (69JA5695). 

Diorganyl tellurides have low molecular mass and are colourless or yellowish liquids with an unpleasant and penetrating odour. Dimethyl telluride is a metabolite of tellurium and tellurium compounds in a variety of living organisms, including humans. Higher dialkyl tellurides and most diaryl tellurides are solids with low melting points (diphenyl telluride is a liquid). 

Tellurium may also be transformed by reduction and methylation (Chasteen and Bentley, 2003). Reduction of tellurite to Te results in a gray to black coloration of microbial colonies, with extracellular and intracellular precipitation being observed (Gharieb et al., 1999). Dimethyl telluride (DMTe) is the main product of Te methylation (Chasteen and Bentley, 2003). 

Although tellurium in elemental form has low toxicity, ingestion can produce nausea, vomiting, tremors, convulsions, and central nervous system depression. In addition, exposure to the metal or to its compounds can generate garlic-like odor in breath, sweat, and urine. Such odor is imparted by dimethyl telluride that is formed in the body. Oral intake of large doses of the metal or its compounds can be lethal. Clinical symptoms are similar for most tellurium salts, which include headache, drowsiness, loss of appetite, nausea, tremors, and convulsions. High exposure can produce metallic taste, dry throat, chill and other symptoms. Inhalation of dust or fume of the metal can cause irritation of the respiratory tract. Chronic exposure can produce bronchitis and pneumonia. 

It proved rather difficult to furnish unequivocal experimental demonstration that transmethylation does indeed take place in biological systems. In 1894, Hofmeister, considering the origin of the garlic-like odor exhaled by animals and men exposed to potassium tellurite, suggested, without proof, that the odor was due to dimethyl telluride and that the methyl group is already present in tissues which possess the capacity for... 

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