Reduction to Diorgano Tellurium Compounds

Diorgano tellurium dihalides react with reducing agents (sodium sulfide, sulfites, hydrazine, thiourea dioxide, sodium borohydride) under mild conditions to give the corresponding diorgano tellurium derivatives in high yields. 

The tendency to replace halide by hydroxide decreases in diorgano tellurium dihalides from chlorine to iodine. In cold or boiling water the dichlorides are converted to diorgano 

Irgolic Organo Tellurium Compounds with 2 Te —C Bonds or 1 Te=C Bond 

Diorgano tellurium dihalides react with sodium alkoxides in alkanols , sodium phenoxides sodium enolates in benzene, and with oximates in methanol to yield diorgano tellurium dialkoxides and diphenoxides. 

Gopinathan, C. Gopinathan, Indian J. Chem., Sect. A 18, 267 (1979). 

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Arenetellurolates, ethenetellurolates, and alkanetellurolates prepared by reduction of diorgano ditellurium compounds with sodium borohydride in ethanol, THF/ethanol, or DMSO add to acetylenes in regioselective and iran.y-stereoselcctive reactions to produce aryl ethenyl tellurium products either predominantly or exclusively as (Z)-isomers. The yields are almost always higher than 70%. In reactions with acetylenic aldehydes, ketones, carboxylic acids, and esters the arenetellurolate becomes bonded to the carbon atom in a [i-position to the carbonyl group. 

Attempts to transesterify diorgano tellurium dialkoxides with 1,2-ethanedithiol or 1,3-propanedithiol caused formation of disulfides and reduction of the diorgano tellurium dialkoxides to the corresponding diorgano tellurium compounds. ... 

Triorgano telluronium salts may lose an organic group to form diorgano tellurium compounds. This reductive elimination is influenced by the nature of the organic groups and the nature of the anion. Methyl" ", benzyl and 2-oxo-2-phenylethyl groups" are especially easy to cleave. However, loss of phenyl iodide was observed when triphenyl telluronium iodide was heated with sodium sulfide nonahydrate . 

Tellurolates, which are easily accessible through reduction of diorgano di telluriums, can be alkylated and arylated and added across carbon-carbon triple bonds. In addition, the weakness of the Te —Te bond in diorgano ditelluriums can be exploited to prepare unsymmetrical diorgano telluriums. Many reagents such as organic lithium compounds,... 

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