From elemental tellurium

9 DIORGANYL TELLURIUM DIHALIDES 3.9.1 From elemental tellurium 

The reaction of elemental teUnrinm with alkyl iodides giving dialkyltellnrinm diiodides is a 100-year-old method/ bnt still finds some nse even if the low yields make this method nnattractive. 

In an improved procednre, employing alkyl chlorides and bromides in the presence of sodium iodide, teUnrinm diiodides are obtained in increased yields.  

Employing appropriate ratios of reagents and experimental conditions, some of the reactions that convert teUnrinm tetrachloride into organyltellurinm trichlorides (see Section 3.5.1) can be applied to the synthesis of diorganyltellnrium dichlorides. 

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The first reported radical reaction promoted by tellurium reagent was probably the conversion of allylic halides into the coupled 1,5-dienes by treatment with telluride anions. The reaction, which gives the best results when employing the reagent prepared in situ from elemental tellurium and lithium triethylborohydride, proceeds through the intermediacy of the thermally unstable bis-allylic telluride followed by extrusion of tellurium and coupling of the formed allylic radicals. 

Lithium telluride (Li2Te) was prepared from elemental tellurium and lithium in the presence of a catalytic amount of naphthalene in THF at room temperature, and then used for the preparation of teUurophenes . 

From Elemental Tellurium and Organolithium and Grignard Reagents 592... 

The classes of organic tellurium compounds mentioned above are prepared by interaction of nucleophilic or electrophilic tellurium species with different classes of organic compounds. Such species are generated from elemental tellurium or from diorganoditellurides 4, as will be discussed in the following sections. 

Preparation of Nucleophilic Tellurium Species 9.13.3.1 From Elemental Tellurium and Reducing Agents... 

Bis-vinylic tellurides 68 can be prepared by reacting monosubstituted alkynes with a hydrotelluration system prepared from elemental tellurium and sodium borohydride in a mixture of ethanol/aqueous sodium hydroxide.133 The stereochemistry of the resulting vinylic tellurides is also Z (Equation (7)). 

It was recently found that selenium dichloride can conveniently be prepared by the reaction of elemental selenium and SO2CI2 It is relatively stable in coordinating solvents and can be used as a reagent for synthetic applications. The attempt to prepare TeCb in the analogous manner from elemental tellurium and SO2CI2 resulted in the formation of various chloridoteUurate anions with different counterions. The solvent and the possible presence of a small amount of residual moisture probably determine the identity of the main product in each individual case. 

A convenient protocol for the synthesis of A-snlphonylimines, which are important synthetic building blocks, involves the reaction of iV,iV -ditosyltellurodiimide generated in situ from elemental tellurium and chloramine-T, with aldehydes in polar or non-polar solvents. ... 

Selenophens and Tellurophens.—The mass spectrometric fragmentations of selenophen and tellurophen have been elucidated they are analogous to that of thiophen. An improved synthesis (Scheme 3) of tellurophen (59) has been described, starting from elemental tellurium and using l,4-bis(trimethylsilyl)buta-... 

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