Aliphatic ditellurides

The short-chain aliphatic ditellurides are liquids with a pungent odour, whereas the higher members (more than IOC chains) are solids with low melting points. 

Nogami et aL [%S] prepared many aliphatic ditelluride polymers by condensing dihalides (x = 2-20) with alkali metal ditelluride ... 

The Te2 group is a chromophore, and aliphatic and aromatic ditellurides exhibit a characteristic orange to pale or dark red colour (absorption maximum at 400 nm). 

Indeed, aliphatic olefins treated with equivalent amounts of diphenyl ditelluride and f-BuOOH in methanol in the presence of sulphuric acid give methoxytellurenylated adducts. ... 

The diaryl or aryl alkyl tellurides are dense yellow oils or crystalline solids, which are easier to handle than the dialkyl tellurides of similar molecular weight. Some of the diaryl derivatives are almost odorless solids. The same comments are valid for the diorganoditellurides 4, which are dark red oils (aliphatic derivatives) and dark red solids (aromatic derivatives). It is recommended that solutions of tellurides or ditellurides should not be kept in contact with air, since an amorphous white solid will form after some time. For some compounds, this reaction with oxygen is very fast. Aliphatic derivatives are more air sensitive than the aromatic ones. In view of this fact, it is recommended to bubble nitrogen into the solutions while a column or thin-layer chromatographic separation is performed. Evaporation of the solvent, however, minimizes the air oxidation. Pure liquids or solids can be handled in air with no need for special precautions, but prolonged exposure to air and to ambient light should be avoided. 

Aliphatic halides react easily with disodium ditelluride to yield dialkyl ditellurium compounds. Although a systematic investigation of this reaction has not yet been carried out, primary alkyl chlorides, bromides and iodides, and secondary alkyl bromides produce the corresponding dialkyl ditellurium derivatives in good yields. 

Diorganyl mono- and ditellurides are the best-known classes of organic tellurium compounds comprising symmetric and unsymmetric alkyl, aryl, and alkyl-aryl tellurides. In addition to acyclic tellurides, heterocychc aliphatic telluroethers as well as aromatic tellurophene-derivatives are known (for a review, see Ref 36). 

Disodium ditelluride can be prepared from tellurium and sodium in liquid ammonia, lithium triethylborohydride in THF, sodium borohydride in ethanol or THF" lithium or sodium in ethylenediamine , sodium hydride in DMF , hydrazine hydrate in aqueous sodium hydroxide , thiourea dioxide in DMF/THF/aqueous sodium hydroxide, and sodium formaldehyde sulfoxylate (Rongalite C) " in aqueous sodium hydroxide. The reducing agents compatible with organic solvents provide reaction media in which long-chain aliphatic halides are soluble. Such halides are insoluble in liquid ammonia, or aqueous media. 

If the diaryl ditelluride is previously converted in situ into the corresponding tellurenyl halide, both the electrophilic tellurium moieties are used. (The stable crystaUine 2-naph-thylteUurenyl iodide (see Section 3.7) reacts similarly.) The reaction is of general application, giving high yields of the expected tellurides with aromatic, aliphatic, cycloaliphatic, vinylid and acetylenic Grignard reagents, under mild conditions. 

Aliphatic Organosulphur Compounds and their Se and Te Analogues 17 Disulphides, Diselenides, and Ditellurides... 

Aromatic disulphides and diselenides adopt a conformation in which the torsion angle between the C—S—S— and —S—S—C— planes lies between 70 and 90°. Related studies of aliphatic disulphides have also been undertaken. Comparisons of S, Se, and O analogues represented by ArXMe, (At = Ph or mem-substituted phenyl) and aryl diarylmethyl sulphides have been made, in terms of their conformational behaviour. Studies of diaryl ditellurides ArTeTeAr and phenyl tellurobenzoates PhCOTeR provide dipole-moment data consistent with a non-planar C conformation and planar Z conformation,... 

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