With Sulfuryl or Thionyl Halides

Diorgano tellurium compounds can be easily converted to diorgano tellurium dihalides in reactions with sulfuryl chloride, bromide, and iodide. Carbon tetrachloride, dichlorometh-ane, diethyl ether, petroleum ether, or benzene have been used as reaction media. Chlorinations with sulfuryl chloride, a liquid reagent, avoid the use of gaseous chlorine. Required amounts of sulfuryl chloride can be more easily measured than those of chlorine. Sulfur dioxide formed during the reaction escapes the reaction mixture as a gas, thus facilitating the isolation of the produet. For these reasons, sulfuryl chloride has been frequently used, whereas sulfuryl bromide and iodide - have been only infrequently employed. 

Diorgano tellurium dihalides were prepared in this manner from dialkyl, alkyl aryl, and diaryl tellurium compounds, and from tellurium heterocycles. However, l-oxo-1,3-dihydro-2-benzotellurophene experienced ring cleavage when reacted with sulfuryl chloride.  

3-Fluorophenyl Methyl Tellurium Dichloride 2.38 g (10 mmol) of 3-fluoromethyl methyl tellurium are dissolved in 20 ml of benzene and the solution is cooled to — 5°. To the stirred, cooled solution are added dropwise 1.35 g (0.81 ml 10 mmol) of sulfuryl chloride dissolved in 10 m/ of benzene and the mixture is stirred for 5 min. 50 ml of dry hexane are then added to complete the precipitation of the product. The precipitate is filtered off, washed with hexane, and recrystallized from 1-propanol yield 3.0 g (100%) m.p. 94 . 

1- naphthyl phenyl tellurium dichloride 4-dimethylaminophenyl 4-methylphenyl 

Thionyl chloride has been used instead of sulfuryl chloride for the chlorination of unsymmetrical diaryl telluriums. The reactions with thionyl chloride are reported to proceed slower than with sulfuryl chloride but produce better formed crystals of the products . 

---