Tellurium hydrogen halides

The other halides of boron and silicon, and also of, phosphorus, sulphur, selenium, tellurium, and iodine, react at once with water, forming hydrogen halide and an acid. The equations are as follows —... 

The free orthotellurous acid is unknown. However, orthotellurous halides (tellurium tetrahalides), the mixed anhydrides derived from orthotellurous acid and hydrogen halides, are well known. 

Tellurium alkoxides were also prepared from the stoichiometrically required amounts of tellurium tetrachloride and alcohol in tetrahydrofuran, with triethylamine serving as the hydrogen halide-scavenger3. 

These compounds are liquids or low melting solids with characteristic foul and persistent odors. They can be stored under an inert atmosphere in the refrigerator for long periods without decomposition. At 20° they decompose slowly to diorgano ditellurium derivatives while in air, tellurium is deposited. Protic agents such as water, hydrogen halides, and alcohols cleave the tellurium-group TV element bond. 

When the reaction mixtures contain copper(II) halides or copper(II) acetate and hydrogen halide, the diaryl ditellurium compounds are oxidized to the corresponding tellurium dihalides1,2. 

Diorgano 4,4-dimethyl-2,6-dioxo-cyclohexylidene tellurium compounds were also converted to diorgano tellurium dihalides by hydrogen halides in boiling ethanol2 and to diorgano tellurium diacetates by acetic acid3. 

The halogens required for this reaction may be generated in situ, for example, through oxidation of hydrogen halides by copper(II) acetate". Organic vicinal dibromides release their bromine atoms to tellurium" ... 

Hydrogen chaloogenides H2X (X = S, Se, Te) react differently with difluoroiodophosphine in the presence of mercury. The sulfur and selenium derivatives give the pentavalent compound XPF2H (X = S, Se), whereas hydrogen telluride produces a mixture of phosphine, hydrogen halides, and elementary tellurium (257). 

Tellurium forms binary teUurides with several metals. The reaction is carried out by heating tellurium with a metal in stoichiometric amounts in the absence of air in an evacuated ampoule. Tellurium reacts with halides of several metals, when heated in a stream of hydrogen, to produce metal tel-lurides. 

In 1996, Detty and coworkers reported on the oxidation of sodium halides to positive halogens with hydrogen peroxide in two-phase systems of dichloromethane and pH 6 phosphate buffer, catalyzed by organoteUurium catalysts 237 (Scheme 181). Mixtures of 1,2-dihalocyclohexane (238) and 2-halocyclohexanol (239) were formed upon reaction of the positive halogens formed with cyclohexene. From the three tellurium catalysts... 

Reaction of methanetellurol with lithium aluminum hydride in diethyl ether caused liberation of hydrogen and formation of lithium tetrakis[methyltelluro]aluminate. This compound was not isolated but reacted with silyl or germyl halides to give silyl or germyl methyl tellurium derivatives4. 

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