Gas phase hydrolysis of sulfur tetrafluoride: A comparison of the gaseous and liquid phase rate constants

摘要

The secondhyphen;order gas phase reaction rate constant for SF4hydrolysis to SOF2has been determined by mass spectrometry and found to be in the range (0.9ndash;2.6)times;10minus;19cm3thinsp;sminus;1at 350 K. The hydrolysis of SOF2in the gas phase is 3 to 4 orders of magnitude slower than that of SF4. Since only liquid phase rate constant data exist for SF4and none for SOF2, our gas phase rate constant for SF4was extrapolated to liquid H2O density for comparison to the literature and was found to be consistent with the rate constant for complete aqueous hydrolysis of SF4, which was indirectly determined by the conductivity change in a pulse radiolysis study of SF6in aqueous solution. The agreement between these values provides direct support for the conclusion of the pulse radiolysis study, namely, that the ratehyphen;determining step involves water attack on SF4. The present data further indicate that SOF2cannot be an intermediate in the aqueous hydrolysis of SF4. A reaction is proposed for both gaseous and liquid phase hydrolyses which involve a common intermediate.