Alkoxy Tellurium Pentafluorides

With Cleavage of the Trimethylsilyl Group from Trimethylsilylaimno Tellurium 

Trimethylsilylamino tellurium pentafluoride lost the trimethylsilyl group in reactions with hydrogen fluorideS cesium fluoride, chlorine fluoride, sulfur fluorides, selenium tetrafluo-ride, phosphorus pentafluoride, tungsten hexachloride, molybdenum hexafluoride, and tungsten hexafluoride.  

Alkoxy tellurium pentafluorides are powerful alkylating agents and must be handled very carefully. The low molecular mass compounds are colorless liquids with a powerful odor. They are hydrolyzed only slowly by water and alkaline solutions. 

---

The reactions of alkoxy tellurium pentafluorides with alcohols in the presence of pyridine were used to prepare dialkoxy tellurium tetrafluorides with two different alkoxy groups in the molecule1. These unsymmetrical compounds are suspected to be predominantly in the cis-form. 

Primary monohydric and polyhydric2 alkanols reacted with tellurium hexafluoride to form alkoxy tellurium pentafluorides. Primary alkanols and equimolar amounts of tellurium hexafluoride in the presence of sodium fluoride or pyridine gave alkoxy tellurium pentafluorides in yields generally higher than 70%3. 

Polyhydric alkanols required an excess of tellurium hexafluoride to hold the reaction at the stage of the alkoxy tellurium pentafluoride. Sodium fluoride was used as the HF-scavenging reagent2. 

Alkoxy tellurium pentafluorides reacted with methanol in the presence of pyridine to form unsymmetrical dialkoxy tellurium tetrafluorides4. 

Alkoxy tellurium pentafluorides are good alkylating reagents. Methoxy tellurium pentafluoride converts diethyl ether to the diethyl(methyl)oxonium salt2. 

Alkoxy tellurium pentafluorides alkylate pyridine, dimethylformamide, dimethylacetami-de, A-methylbenzaldimide, and potassium phthalimide3. 

Methoxy tellurium pentafluoride is the most reactive alkoxy tellurium pentafluoride. Higher alkoxy compounds require longer reaction times and 20° for their reaction with pyridine, whereas methoxy tellurium pentafluoride already reacts at — 40°... 

Diethyl ether cannot be used in these reactions because it will be alkylated by the alkoxy tellurium pentafluoride. ... 

---