19F NMR and UV studies of xenon difluoride solution-vessel stability and its relevance to the fluorination of organic substrates

Abstract

The stability of xenon difluoride in CH2Cl2, CHCl3, CFCl3, CH3CN, H2O and C 6F6, and the corresponding deuterated solvents, in PTFE-FEP, Pyrex® and quartz tubes has been investigated using 19F NMR spectroscopy. Stability in tubes lined with PTFE-FEP is good. With the exception of CHp3CN, decomposition in Pyrex® tubes occurs within a few hours and this instability is attributable to coordination to Lewis acid sites on the glass surface. In quartz the lifetime of the xenon difluoride is extended by a few hours. The mode of reaction of xenon difluoride with organic substrates depends on the reaction vessel surface and the type of solvent. Pyrex® catalysis in a suitable solvent such as CH2Cl2 is a convenient way of achieving electrophilic reactions of xenon difluoride. The UV spectra of xenon difluoride in CH 3CN and CH3CN: H2O (3:1) have been recorded.