From Tellurium Dioxide

Tellurium dioxide dissolved in dilute hydrochloric acid reacted with four moles of potassium (9-alkyl dithiocarbonates to produce tellurium bis[(9-alkyl dithiocarbonates]  

Tellurium Bis[(7-isopropyl dithiocarbonate] 2.0 g (12.5 mmol) of tellurium dioxide are dissolved in 50 ml of dilute aqueous hydrochloric acid and then 8.7 g (50 mmol) of potassium 0-isopropyl dithiocarbonate dissolved in water are added with stirring. The mixture is immediately extracted with 50 ml of chloroform, the organic phase is separated, and the chloroform is evaporated under reduced pressure. The oily residue is dissolved in 40 ml of dichloromethane and this solution is allowed to stand at 20° until deep-red crystals separate yield not reported m.p. not reported. 

Tellurium bis[0-ethyl dithiocarbonate] was obtained as a precipitate by mixing aqueous solutions of the starting materials. The product was recrystallized from ethanoF. 

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Solutions of sodium tellurite in water1,2 or prepared from tellurium dioxide and aqueous sodium hydroxide3 were acidified with sulfuric acid and treated with freshly prepared solutions of bis[2-hydroxyethyl]dithiocarbamic acid in aqueous methanol. Addition of aqueous solutions of potassium chloride, iodide, or thiocyanate led to the deposition of crystalline tris[bis(2-hydroxyethyl)dithiocarbamate] halides. 

The compound decomposed on storage with deposition of tellurium1. Tellurium tetrachloride need not be used in substance it can be generated in the reaction mixture from tellurium dioxide and acetyl chloride or chlorotrimethylsilanc. With acetyl bromid tellurium tetrabromide can be formed. When cyclohexene was present in the reaction mixture, 2-halocyclohexyl tellurium trihalides were isolated in approximately 70% yields. Acetic acid, chloroform, or dichloromethane may be used as solvents2. 

When phenylacetylenes (3 mol), tellurium dioxide (1 mol), and a lithium halide (14-18 mol) were refluxed in acetic acid, 3-halobenzotellurophenes were obtained in yields ranging from 21 to 92%2. A tellurium(IV) acetate halide, formed from tellurium dioxide, lithium halide, and acetic acid, probably adds to the carbon-carbon triple bond of the phenylacetylene. The intermediary 2-phenyl-2-haloethenyl tellurium acetate halide cyclizes probably by loss of acetic acid. The 3-halobenzotellurophene Te, 7e-acetate halide is then reduced to 3-halobenzotellurophene by an excess of the phenylacetylene. Diphenylacety-lene and diphenyldiacetylene did not react under these conditions. 

Table 20 Benzotellurophenes prepared from tellurium dioxide, lithium halide, and phenylacetylene in refluxing acetic acid1...

The additions of tellurium tetrahalides to olefins in the presence of alcohols proceed equally well when the tetrahalides are generated in the reaction mixture from tellurium dioxide and chlorotrimethylsilane in methanoP or concentrated hydrochloric acid/methanol. trans-2-Methoxycyclohexyl tellurium trichloride was obtained in this manner in quantitative yield . In the reactions of terminal alkenes, the TeCl3 group (from TeO and concentrated hydrochloric acid) added according to the Markovnikov rule producing 2-alkoxy-1 -alkyl tellurium trichlorides. The trichlorides were not isolated but were reduced with disodium disulfite to the ditellurium compounds, which, in turn, were converted to the tellurium trichlorides by treatment with sulfuryl chlorides. For data on these tellurium trichlorides see p. 316. The overall yields range from 15 to 70%. 

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