Tetraalkoxy Tellurium Difluorides

Tetraalkoxy tellurium difluorides exist as cis- and tran.7-isomers. Several derivatives belonging to this class of compounds were prepared, but few were isolated in pure form. 

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Trifluoroethanol had not formed any tetraalkoxy tellurium difluoride after 9 days. After 28 days the mixture contained 29% of this compound. In reactions with prop-2-en-l-ol, decomposition occurred after five days. The reaction between tellurium hexafluoride and n-propanol produced no tetrapropoxy tellurium difluoride1. 

Tetraalkoxy Tellurium Difluorides 5 g of tetraalkoxy tellurium are placed in a conical flask in a dry box, and the vessel is then conneeted to a vacuum line, cooled to —78°, and 20 ml of fluorotrichloromethane are condensed into the vessel. The mixture is vigorously stirred at —78° and a stream of fluorine diluted with 4 parts of nitrogen is passed over the mixture for 3 h, thus providing a four-fold excess of fluorine. The apparatus is then purged with nitrogen, fluorotrichloromethane is allowed to evaporate, and the residue is extracted with chloroform. The chloroform is evaporated and the residue is distilled under vacuum. 

Tellurium hexafluoride heated with at least 4.5 molar equivalents of a primary alcohol at 90° for 9 days in the presence of excess sodium fluoride, formed a mixture of alkoxy tellurium fluorides containing cis- and tetraalkoxy tellurium difluorides. These mixtures could not be separated by distillation. The compounds were identified by F-NMR spectroscopy. 

Tetraalkoxy Tellurium Difluorides The required amount (0.16 mol) of alkanol and 90 g (2.1 mol) of dry sodium fluoride are placed in a 600-ml reaction tube. The tube is cooled in liquid nitrogen, evacuated to 0.001 torr, and 8.6 g (35.6 mmol) of tellurium hexafluoride are condensed into the tube, which is then sealed. The tube is allowed to warm to 20°, then heated at 90° for 9 days, cooled, and opened. The mixture is extracted with chloroform, the extract is evaporated, and the residue is distilled under vacuum. 

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