Cesium tellurides

Portman R, Quin M, Sagert N et al (1989) A Knudsen cell mass-spectrometer study of the vaporization of cesium telluride and cesium tellurite. Thermochim Acta 144 21-31 Piacente V, Scardala P (1994) A study on the vaporization of copper(II) selenide. J Mater Sd Lett 13 1343-1345... 

The thermally induced redistribution of the tellurium and selenium isotopes shown under certain conditions might be due to the formation of cesium telluride and selenide both compounds exhibit comparatively high vapor pressures (10- MPa at 1000 K, 0.1 MPa at 2000 K). 

The title reagent (prepared by the reaction of sodium hydrogen telluride with chlorotriph-enylstannane) reacts easily with the more active halides such as benzyl bromides whereas common halides need to be activated by cesium fluoride. 

With a catalytic amount of diisobutyi telluride method B. Chalcone (0.5 mmol), cesium carbonate (1.0 mmol), ( )-3-bromo-l-trimethylsilylprop-l-ene (0.75 mmol), diisobutyi telluride (0.1 mmol), THF (5 cm ) and water (5 mm ) were mixed in a reaction tube and stirred at 50°C for a specific period of time. After 28 h, additional trimethylsilylallyl bromide (0.25 mmol) was added and stirring continued for 20 h. When the reaction was complete (monitored by TLC), work-up as for method A and flash chromatography of the residue on silica gel afforded the product, of purity >98% (GC). 

The reduction of the di(selenocyanato)propane 169 with sodium borohydride gave the corresponding diselenolate, which reacted with 3-chloropropan-l-thiol to give the dithiol 238 in 60% yield. A soft base like cesium carbonate in DMF was able to deprotonate the dithiol and treatment with 1,3-dibromopropane afforded the sulfur and selenium 16-membered ring heterocycles 239 in 22% yield <2000IC2558>. Bis(o-formylphenyl)telluride 241 was synthesized... 

A useful and practical version of the above protocol involves a catalytic process in which the enone, a bromoallyl silane, cesium carbonate and diisobutyl telluride react in a one-pot procedure to give the desired cyclopropanes with a high c -stereoselectivity. 

Additional studies (Collins et al., 1987) have, on the whole, confirmed the results mentioned above. According to these experimental investigations (which were performed in the ORNL heating device), tellurium is transported from the fuel pellet to the pellet - cladding gap most probably as the tellurides of cesium and rubidium... 

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