From Alkoxy Tellurium Pentafluorides

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 molecule. These unsymmetrical compounds are suspected to be predominantly in the cw-form. 

Ethoxy Methoxy Tellurium Tetrafluoride 1.0 g (3.7 mmol) of ethoxy tellurium pentafluoride are dissolved in 10 m/ of carbon tetrachloride, 0.4 g (12.5 mmol) of methanol are added, and the mixture is cooled to —20°. 0.4 g (5.1 mmol) of pyridine are added dropwisc to the cold solution, the mixture is extracted with very dilute hydrochloric acid to remove pyridinium fluoride, and the organic layer is separated, and dried with anhydrous sodium sulfate. The mixture is filtered, carbon tetrachloride is distilled off under reduced pressure, and the product is distilled under vacuum yield 0.65 g (63%) b.p. 65°/20 torr. 

Reactions of methoxy tellurium pentafluoride with alcohols also produced unsymmetrical methoxy alkoxy tellurium tetrafluorides but in lower yields than those achieved in reactions with methanol. Methoxy tellurium pentafluoride is partly lost through methylation of pyridine.  

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