Telluride, dialkyl reductions

The discovery of efficient methods for the reduction of tellurium in organic media to disodium telluride, which can be alkylated in situ, led to the preparation of many dialkyl telluriums. The greatest progress has been achieved, however, in the preparation of unsymmetrical diorgano telluriums by alkylation or arylation of tellurolates or by modification of the organic groups in diorgano telluriums. 

One common present day preparation of dialkyl mono-and ditellurides involves the reaction of alkyl halides with alkali metal tellurides that have been prepared in situ. The reactions are commonly carried out in aqueous or nonaqueous solutions. Solutions of sodimn in liquid ammonia also provide a useful media for the reduction of tellurium. ... 

Sodium telluride and ditelluride are readily generated in situ from Te by reduction with thiourea dioxide, and subsequent treatment with alkyl halide provides the corresponding dialkyl tellurides and ditellurides. E Thiourea dioxide and NaOH in 1 1 water/THF added to Te under N2, the mixture refluxed for 1 h, n-octyl halide and a little cetyltrimethylammonium bromide in THF added, and refluxing continued for 1 h - dioctyl telluride. Y 85%. The method is cheap, simple and does not require very dry conditions. F.e. and sym. ditellurides s. J.T.B. Ferreira et al., Synth. Commun. 19, 239-44 (1989) prepn. of Na2Te from ultra-pure Te-ingots/Na-naphthalenide, or from Te/Na and a little naphthalene, s. K.T. Higa, D.C. Harris, Organometallics 8, 1674-8 (1989). 

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