Fluorinating agents selenium tetrafluoride

We also developed a number of other useful new fluorinating reagents. They ineluded a convenient in situ form of sulfur tetrafluoride in pyridinium polyhydrogen fluoride, selenium tetrafluoride, and ey-anurie fluoride. We introdueed uranium hexafluoride (UFg), depleted from the U-235 isotope, which is an abundant by-product of enrichment plants, as an effective fluorinating agent. 

Selenium tetrafluoride, which can be prepared from selenium metal and chlorine trifluoridc (CIF3), was introduced by Olah as a fluorinating agent for carbonyl compounds and alcoholsT It is generally necessary to add pyridine in the reactions with alcohols I. Pyridine forms a I 1 complex with selenium tetrafluoride and neutralizes the hydrogen fluoride which is formed in the fluorination reaction. 

Essentially the same route as that of Ruff has been followed by us, except that two new reducing agents whose chemistry is under study in these laboratories, namely sulphur and selenium tetrafluorides, have been used. Attention has already been drawn to the usefulness of selenium tetrafiuoride as a mild reducing agent in fluorine chemistry while sulphur tetrafiuoride also gives evidence of possessing similar properties. In the first series of experiments, palladium trifluoride, formed by the reaction between palladous iodide and elementary fluorine at room temperature, was treated with a stream of sulphur tetrafluoride at 250-300°. The violet-coloured powder which resulted was proved, by Af-ray examination, to contain palladium difluoride in admixture with about 10% of palladium metal. 

Both tetrafluorides can be synthesized from the action of SF4 on the dioxides. Selenium tetrafluoride is a white solid that melts to a colorless liquid. It can be handled in rigorously dried Pyrex, reacting slowly with glass but violently with H2O. Selenium tetrafluoride can solvate many fluorides. Selenium tetrafluoride and other organic Se fluorides have been utilized as fluorinating agents for alcohols and carbonyl compounds. 

Table 16.6 fists selected properties of Sep4, SeFg, Tep4 and TeFg. Selenium tetrafluoride is a good fluorinating agent. It is a liquid at 298 K and (compared with SF4) is relatively... 

The noncatenated halides include the relatively inert sulfur hexafluoride and the highly reactive tetrafluorides of sulfur, selenium, and tellurium. SFg( ) is useful in insulators and pressurized athletic equipment. SF4( ) is an important fluorinating agent. Two important oxyhalides are thionyl and sulfuryl chloride. The former is particularly useful in preparing anhydrous metal halides. 

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