Phosphoryl bromide fluoride

Phosphoryl bromide (POBr ) BraOiPiCg) 503 Potassium fluoride (K(HFg)) FaHiKid) 1064... 

Nonmetal Halides. Vigorous or explosive reactions occur with phosphorus tribromide on addition of drops of water,20 phosphorus trichloride, phosphorus pentachloride,21 diselenium dichloride,22 sulfur dichloride, boron tribromide, sulfur dibromide,17 seleninyl bromide,23 phosphoryl chloride, sulfinyl fluoride, silicon tetrachloride, and silicon tetrafluoride.24... 

The displacement reactions of phosphoryl chlorides sometimes occur without total stereospecificity as a result of racemization brought about by CT Racemization should not occur in displacements which lead to acid fluorides, particularly under the very mild conditions (in MeCN at room temperature) used with the bromide here, the thioic (-)-bro-mide afforded (+)-fluoride in a displacement thought to proceed with at least 90% enan-tioselectivity. Since hydrolysis of the thioic fluoride resulted in the formation of the (+)-acid, the argument adopted in the previous paragraph would then suggest that the displacement of bromide by fluoride must have occurred with inversion of configuration. ... 

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